Silk yarn and yarn spun from silk waste; silk-worn gut

1. Scope and Applicability

This PCR applies to foreground production of saleable silk yarn made from incoming raw silk, spun silk yarn made from silk waste, and silkworm gut formed from a dissected silkworm silk gland. The product is modelled at the producer's factory gate before dyeing, weighting, weaving, knitting, retail packaging, and outbound distribution.

The declared route determines which process sections apply. A foreground data package shall not combine reeled or thrown filament yarn, yarn spun from silk waste, and silkworm gut into one undeclared production mix. Sericulture, cocoon production, raw-silk production, and production of purchased silk waste are upstream processes represented by linked datasets rather than by invented foreground values.

2. Product Category Identity

Field	Value
canonical_pcr_id	pcr.food-products-beverages-and-tobacco-textiles-apparel-and-leather-products.yarn-and-thread-woven-and-tufted-textile-fabrics.silk-yarn-and-yarn-spun-from-silk-waste-silk-worn-gut
classification_refs	CPC 3.0: 26310, Silk yarn and yarn spun from silk waste; silk-worn gut
covered_products	Thrown or twisted filament silk yarn made from incoming raw silk; spun silk yarn made from silk waste; silkworm gut formed from a silkworm silk gland
excluded_products	Raw silk not thrown (CPC 26110); woven or knitted silk fabric; dyed or weighted silk unless the treatment is explicitly included as an additional foreground process; synthetic or regenerated filament yarn; finished sutures or fishing tackle; retail packaging
representative_product	Undyed spun silk yarn made from degummed silk waste
production_route	One declared route: filament-yarn forming from raw silk; silk-waste degumming, dressing and spinning; or acid-assisted silkworm-gut forming
market_state	Unpackaged, undyed, unweighted saleable yarn or silkworm gut at the factory gate, with declared moisture/conditioning state and quality specification

3. Reference Flow

Field	Value
What	Saleable silk yarn or silkworm gut providing a declared textile-yarn or gut-filament specification
How much	1 kg net dry product mass, excluding any carrier, cone, wrap, pallet, or other packaging
How well	Meets the declared route, material origin, sericin condition where applicable, yarn construction, linear density or gut diameter, twist where applicable, and tensile-quality specification
How long or cycle	One production batch delivered at the factory gate; no use-stage duration is assigned to this intermediate product
reference_flow_link	reference_product

Field	Value
Reference amount	1 kg net dry product
Reference product flow	Spun Silk 6c639604-29e8-44b6-be18-4e0ad97fdef8
Reference flow property	Mass 93a60a56-a3c8-11da-a746-0800200b9a66
Reference unit group	Units of mass 93a60a57-a4c8-11da-a746-0800200c9a66
Reference unit	kg
Required qualifiers	product route; silk source and species where known; filament or staple form; sericin condition where applicable; single, folded or cabled construction; linear density in tex or, for silkworm gut, diameter and length; twist direction and twist level where applicable; moisture or conditioning basis; quality-test method; production geography; included processing steps; production period

When constructing a foreground data package, every item listed in Required qualifiers shall be declared in dataset metadata, process notes, reference-flow comments, the product description, or an equivalent data-package field. A route-inapplicable qualifier shall be explicitly marked not applicable rather than omitted.

4. Measurement and Unit Rules

rule_id	Applies to	Required property	Required unit	Rule
reference_dry_mass	reference product and all mass-balance flows	Mass 93a60a56-a3c8-11da-a746-0800200b9a66	kg	Report net product mass on the declared dry or conditioned basis; retain measured gross mass, packaging tare, moisture or conditioning method, and conversion calculation.
linear_density_tex	silk yarn and silkworm gut when linear density is specified	Linear density	tex	Express and convert linear density using the Tex System; if measured from yarn packages, declare the conditioning and test procedure.
electricity_metering	each electricity card	Energy	kWh	Record the electricity supply voltage and supply scenario, preserve metered kWh, and do not merge electricity with steam, natural gas, or other energy carriers.
steam_metering	delivered steam	Mass	kg	Record delivered steam mass, pressure, condensate-return boundary, and meter or invoice basis; any conversion to energy shall retain the measured steam state and calculation inputs.
fuel_metering	gaseous natural gas	Mass	kg	Preserve purchased fuel mass and declared supply state; if volume or energy is the raw record, retain measured conditions and the site-specific conversion factor.
chemical_active_mass	sodium carbonate and acetic acid	Mass	kg	Report each chemical separately as product mass or active-substance-equivalent mass using supplier concentration and batch issue records; do not aggregate chemicals.

5. System Boundary

rule_id	Applies to	Rule	source_ids
boundary_route_gate	all routes	Include only the declared route processes under direct foreground control, from receipt of raw silk, silk waste, or dissected silk glands through saleable unpackaged product at the factory gate.	unsd-cpc-3-0-2025; iso-14044-2006
boundary_upstream_links	purchased inputs	Link raw silk, silk waste, silk glands, water, chemicals, electricity, steam, and natural gas to upstream datasets with disclosed geography, technology, and supply scenario; do not assign zero burdens to purchased inputs.	iso-14044-2006
boundary_route_selection	product identity	Select one route and declare every included optional step. Silk-waste yarn requires degumming/dressing and spinning; filament yarn requires forming/twisting/winding; silkworm gut requires acid-assisted gland stretching.	eu-textiles-bref-2023; yin-et-al-2021-spun-silk; cenis-et-al-2015-silkworm-gut
boundary_wet_operations	degumming and washing	Include process water, each chemical, delivered steam, electricity, saleable recovered sericin when produced, and the sericin-bearing wastewater leaving the process.	eu-textiles-bref-2023; ifc-textiles-ehs-2007
boundary_actual_atomic_exchanges	all foreground processes	Record every actual material, chemical, electricity supply, steam supply, fuel, waste stream, recovered product, and direct elementary emission as a separate exchange; a flow not pre-listed in this PCR shall still be added as one specific atomic exchange.	eu-textiles-bref-2023; ifc-textiles-ehs-2007
boundary_exclusions	downstream and upstream processes	Keep sericulture, cocoon production, raw-silk production, dyeing, weighting, fabric formation, product use, retail packaging, and outbound distribution outside the foreground boundary unless the declared study explicitly adds them as separate processes.	unsd-cpc-3-0-2025; eu-textiles-bref-2023

Boundary Abstraction

Field	Value
declared_starting_condition	One route-specific material received at the foreground facility: raw silk, silk waste, or a dissected silkworm silk gland
starting_condition_role	Upstream product input to a directly controlled yarn- or gut-forming route
product_classification_scope	CPC 3.0 code 26310 output; incoming raw silk and recovered silk waste retain their own product identities
recursive_input_rule	A CPC 26310 silk-yarn input used for gassing or another directly controlled finishing step remains an explicit product input and links to its upstream process; it is not recursively expanded inside the same process.
upstream_dataset_requirement	A geographically and technologically representative upstream dataset is required for every purchased input and utility; proxy use shall be disclosed and justified.
disclosure	Declare route, starting material, sericin condition, included mechanical and wet processes, gassing status, production geography and period, allocation method, and all unresolved or proxy identities.

6. Process Inventory Structure

Process Map

process_id	process_name	inclusion	inclusion_condition	role	quantitative_reference
silk_filament_yarn_forming	Filament silk yarn forming, twisting and winding	conditional	Required when the declared product is filament silk yarn made from incoming raw silk	Foreground filament-yarn production	Per 1 kg net dry filament silk yarn output
silk_waste_degumming_dressing	Silk-waste degumming and dressing	conditional	Required when the declared product is yarn spun from silk waste	Foreground wet preparation and fibre dressing	Per kg degummed silk fibre output transferred to spinning
spun_silk_spinning	Spun-silk drafting, spinning, plying and winding	conditional	Required when the declared product is yarn spun from silk waste	Foreground spun-yarn production	Per 1 kg net dry spun silk yarn output
spun_silk_gassing	Spun-silk yarn gassing	conditional	Included only when protruding fibres and neps are removed with a fuel-gas flame	Foreground route-specific yarn finishing	Per 1 kg net dry gassed spun silk yarn output
silkworm_gut_forming	Silkworm-gut acid conditioning and stretching	conditional	Required when the declared product is silkworm gut	Foreground gut-filament forming	Per 1 kg net dry silkworm gut output

Process: Filament silk yarn forming, twisting and winding (silk_filament_yarn_forming)

Inputs

Product flows

Incoming raw silk (filament_raw_silk_input)

Raw silk crosses the foreground boundary for doubling, twisting, throwing and winding into filament yarn.

• Selected flow: Raw Silk 343df125-d682-4ffa-8829-5fbc785bdbc9
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Weighed net dry or conditioned mass issued to the route, less returned unused material
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry filament silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_filament_batch_records
• Sources: eu-textiles-bref-2023

Medium-voltage grid electricity (filament_electricity)

Electricity used by twisting, throwing, winding, ventilation and directly assigned auxiliary equipment is recorded separately from heat and fuel.

• Selected flow: Electricity, medium voltage, grid supply at plant
• Flow property / unit: Energy / kWh
• Amount rule: Route-assigned interval meter reading or documented submeter allocation
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry filament silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_filament_electricity_meter

Waste flows

Elementary flows

Outputs

Product flows

Saleable filament silk yarn (filament_yarn_output)

The output is thrown or twisted filament silk yarn meeting the declared construction and linear-density specification.

• Selected flow: Silk filament yarn, thrown and wound
• Flow property / unit: Mass / kg
• Amount rule: Weighed net dry or conditioned conforming output
• Value mode: Foreground record (foreground_record)
• Specificity: Product-specific (product_specific)
• Normalization basis: route output before packaging
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_filament_batch_records
• Sources: iso-1144-2016; iso-2060-1994; iso-2062-2009

Recovered silk waste (filament_recovered_silk_waste)

Silk offcuts and broken filament transferred as a usable input to another production system are recorded as this product output.

• Selected flow: Silk waste e8fb97e6-a2ec-40d6-8dee-2cafe1a25106
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Weighed mass accepted for recovery and transferred out of the process
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry filament silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_filament_batch_records
• Sources: yin-et-al-2021-spun-silk

Waste flows

Discarded silk waste (filament_discarded_silk_waste)

Silk residues not accepted for recovery and sent to waste management are recorded separately from recovered silk waste.

• Selected flow: Silk waste 690d2d6b-d573-4ab5-9e50-742a2ee12275
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Weighed mass crossing the waste-management boundary
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry filament silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_filament_batch_records

Elementary flows

Process: Silk-waste degumming and dressing (silk_waste_degumming_dressing)

Inputs

Product flows

Incoming silk waste (waste_degumming_silk_input)

Silk waste is the route-specific raw material and is recorded as a product input when purchased or transferred for recovery.

• Selected flow: Silk waste e8fb97e6-a2ec-40d6-8dee-2cafe1a25106
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Weighed received mass issued to the batch, corrected to the declared moisture basis
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per kg degummed silk fibre output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_degumming_batch_records
• Sources: yin-et-al-2021-spun-silk

Process water (waste_degumming_water)

Water entering degumming, washing and rinsing is recorded as one water product input.

• Selected flow: Process Water 94a04f7e-2d5c-41f0-b182-d54a3b373a02
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Metered process-water mass, or metered volume converted with recorded water density
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per kg degummed silk fibre output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_degumming_water_meter
• Sources: eu-textiles-bref-2023

Sodium carbonate (waste_degumming_sodium_carbonate)

Sodium carbonate is recorded only for a batch whose documented degumming recipe uses this specific alkali.

• Selected flow: Sodium carbonate 5462c2da-d3dd-41f0-a78f-51024d2d1a69
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Net chemical mass issued to the batch from weighed issue records or supplier invoice reconciliation
• Value mode: Foreground record (foreground_record)
• Specificity: Technology-specific (technology_specific)
• Normalization basis: per kg degummed silk fibre output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_degumming_batch_records
• Sources: eu-textiles-bref-2023

Supplied steam (waste_degumming_steam)

Steam crossing the process boundary for bath heating is recorded separately from electricity and fuel.

• Selected flow: Steam, 10 bar, supplied to plant
• Flow property / unit: Mass / kg
• Amount rule: Metered delivered steam mass assigned to the batch; declare pressure and condensate-return boundary
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per kg degummed silk fibre output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_degumming_steam_meter
• Sources: eu-textiles-bref-2023

Medium-voltage grid electricity (waste_degumming_electricity)

Electricity used by bath circulation, washing, dressing, combing and directly assigned auxiliaries is recorded independently.

• Selected flow: Electricity, medium voltage, grid supply at plant
• Flow property / unit: Energy / kWh
• Amount rule: Route-assigned interval meter reading or documented submeter allocation
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per kg degummed silk fibre output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_degumming_electricity_meter

Waste flows

Elementary flows

Outputs

Product flows

Degummed silk fibre (degummed_silk_fibre_output)

The dressed fibre output has the route-declared portion of sericin and contaminants removed and is ready for drafting and spinning.

• Selected flow: Degummed silk fibre
• Flow property / unit: Mass / kg
• Amount rule: Weighed net dry or conditioned fibre mass transferred to spinning
• Value mode: Foreground record (foreground_record)
• Specificity: Product-specific (product_specific)
• Normalization basis: degumming and dressing batch output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_degumming_batch_records
• Sources: eu-textiles-bref-2023; yin-et-al-2021-spun-silk

Recovered sericin (recovered_sericin_output)

Sericin isolated as a saleable product is recorded only when recovery, product quality and transfer are documented; dissolved sericin remaining in wastewater is not this product.

• Selected flow: Recovered sericin
• Flow property / unit: Mass / kg
• Amount rule: Weighed dry recovered sericin meeting the declared product specification
• Value mode: Foreground record (foreground_record)
• Specificity: Technology-specific (technology_specific)
• Normalization basis: per kg degummed silk fibre output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_degumming_batch_records
• Sources: eu-textiles-bref-2023

Waste flows

Silk degumming wastewater (degumming_wastewater)

The sericin-bearing aqueous stream sent to on-site or off-site treatment is recorded as one route-specific waste flow.

• Selected flow: Silk degumming wastewater
• Flow property / unit: Mass / kg
• Amount rule: Metered discharge mass, or measured volume converted with recorded density, assigned to the batch before treatment
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per kg degummed silk fibre output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_degumming_batch_records
• Sources: eu-textiles-bref-2023; ifc-textiles-ehs-2007

Elementary flows

Process: Spun-silk drafting, spinning, plying and winding (spun_silk_spinning)

Inputs

Product flows

Degummed silk fibre input (spinning_degummed_silk_input)

Degummed, dressed silk fibre crosses into drafting and spinning as one specific intermediate product.

• Selected flow: Degummed silk fibre
• Flow property / unit: Mass / kg
• Amount rule: Weighed net dry or conditioned fibre mass issued to spinning
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry spun silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_spinning_batch_records
• Sources: yin-et-al-2021-spun-silk

Medium-voltage grid electricity (spinning_electricity)

Electricity used by drafting, roving, spinning, plying, winding, ventilation and directly assigned auxiliary equipment is recorded independently.

• Selected flow: Electricity, medium voltage, grid supply at plant
• Flow property / unit: Energy / kWh
• Amount rule: Route-assigned interval meter reading or documented submeter allocation
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry spun silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_spinning_electricity_meter

Waste flows

Elementary flows

Outputs

Product flows

Spun silk yarn (spun_silk_output)

The conforming output is the representative reference product for the silk-waste spinning route.

• Selected flow: Spun Silk 6c639604-29e8-44b6-be18-4e0ad97fdef8
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Weighed net dry or conditioned conforming output
• Value mode: Foreground record (foreground_record)
• Specificity: Product-specific (product_specific)
• Normalization basis: route output before packaging
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_spinning_batch_records
• Sources: iso-1144-2016; iso-2060-1994; iso-2062-2009; yin-et-al-2021-spun-silk

Waste flows

Discarded silk waste (spinning_silk_waste)

Short fibres, neps and off-specification silk sent to waste management are recorded as one silk-waste flow.

• Selected flow: Silk waste 690d2d6b-d573-4ab5-9e50-742a2ee12275
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Weighed mass crossing the waste-management boundary
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry spun silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_spinning_batch_records
• Sources: yin-et-al-2021-spun-silk

Elementary flows

Process: Spun-silk yarn gassing (spun_silk_gassing)

Inputs

Product flows

Ungassed spun silk yarn (gassing_spun_silk_input)

Spun silk yarn enters this optional process only when a fuel-gas flame is used to remove protruding fibres and neps.

• Selected flow: Spun Silk 6c639604-29e8-44b6-be18-4e0ad97fdef8
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Weighed net dry or conditioned input to the gassing line
• Value mode: Foreground record (foreground_record)
• Specificity: Technology-specific (technology_specific)
• Normalization basis: per 1 kg net dry gassed spun silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gassing_batch_records
• Sources: yin-et-al-2021-spun-silk

Gaseous natural gas (gassing_natural_gas)

Natural gas consumed by the gassing flame is recorded as one fuel input.

• Selected flow: natural gas in the gaseous state 4f19ca0e-7b3b-11dd-ad8b-0800200c9a66
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Metered or invoiced fuel mass assigned to the gassing line and production batch
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry gassed spun silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gassing_gas_meter
• Sources: yin-et-al-2021-spun-silk

Medium-voltage grid electricity (gassing_electricity)

Electricity used by the gassing machine, drive, controls and directly assigned extraction equipment is recorded separately from natural gas.

• Selected flow: Electricity, medium voltage, grid supply at plant
• Flow property / unit: Energy / kWh
• Amount rule: Line submeter reading or documented allocation from interval-meter records
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry gassed spun silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gassing_electricity_meter

Waste flows

Elementary flows

Outputs

Product flows

Gassed spun silk yarn (gassing_spun_silk_output)

The output is conforming spun silk yarn after the declared gassing operation.

• Selected flow: Spun Silk 6c639604-29e8-44b6-be18-4e0ad97fdef8
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Weighed net dry or conditioned conforming output
• Value mode: Foreground record (foreground_record)
• Specificity: Product-specific (product_specific)
• Normalization basis: route output before packaging
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gassing_batch_records
• Sources: yin-et-al-2021-spun-silk

Waste flows

Captured silk waste from gassing (gassing_silk_waste)

Captured burnt fibre, neps and off-specification silk sent to waste management are recorded as silk waste.

• Selected flow: Silk waste 690d2d6b-d573-4ab5-9e50-742a2ee12275
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Weighed captured material crossing the waste-management boundary
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry gassed spun silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gassing_batch_records
• Sources: yin-et-al-2021-spun-silk

Elementary flows

Fossil carbon monoxide to air (gassing_carbon_monoxide_air)

Direct fossil carbon monoxide leaving the gassing process to unspecified air is recorded from route-specific monitoring or a validated site emission inventory.

• Selected flow: carbon monoxide (fossil) 08a91e70-3ddc-11dd-924e-0050c2490048
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Measured or site-inventory mass emitted after abatement; no default factor is supplied by this PCR
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry gassed spun silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gassing_air_monitoring
• Sources: yin-et-al-2021-spun-silk; ifc-textiles-ehs-2007

Fine particulate matter to air (gassing_particulate_air)

Direct fine particulate matter not captured by the extraction or abatement system is recorded separately from captured silk waste.

• Selected flow: Particulate matter, <2.5 µm, to air
• Flow property / unit: Mass / kg
• Amount rule: Measured emitted mass after abatement; no default factor is supplied by this PCR
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry gassed spun silk yarn output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gassing_air_monitoring
• Sources: yin-et-al-2021-spun-silk; ifc-textiles-ehs-2007

Process: Silkworm-gut acid conditioning and stretching (silkworm_gut_forming)

Inputs

Product flows

Silkworm silk gland (silk_gland_input)

A dissected Bombyx mori silk gland is the specific biological material entering the gut-forming route.

• Selected flow: Silkworm silk gland
• Flow property / unit: Mass / kg
• Amount rule: Weighed fresh gland mass issued to the forming batch
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry silkworm gut output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gut_batch_records
• Sources: cenis-et-al-2015-silkworm-gut

Process water (silkworm_gut_water)

Water used to prepare the acid bath and rinse the formed gut is recorded separately from acetic acid.

• Selected flow: Process Water 94a04f7e-2d5c-41f0-b182-d54a3b373a02
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Metered water mass, or metered volume converted with recorded water density
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry silkworm gut output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gut_water_meter
• Sources: cenis-et-al-2015-silkworm-gut

Acetic acid (silkworm_gut_acetic_acid)

Acetic acid in the conditioning bath is recorded as pure-acid-equivalent mass, distinct from bath water.

• Selected flow: Acetic acid (acetic acid) c7564d76-47c4-440c-9eb8-3242c38eeb1b
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: Solution mass multiplied by the supplier-certified acetic-acid mass fraction using calc_acetic_acid_active_mass
• Value mode: Calculated value (calculated_value)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry silkworm gut output
• Basis kind: Process output (process_output)
• Evidence kind: Calculated from collection (calculated_from_collection)
• Collection protocol: cp_gut_acid_records
• Sources: cenis-et-al-2015-silkworm-gut

Waste flows

Elementary flows

Outputs

Product flows

Saleable silkworm gut (silkworm_gut_output)

The output is acid-conditioned and stretched silkworm gut meeting the declared diameter, length and tensile specification.

• Selected flow: Silkworm gut
• Flow property / unit: Mass / kg
• Amount rule: Weighed net dry conforming product mass
• Value mode: Foreground record (foreground_record)
• Specificity: Product-specific (product_specific)
• Normalization basis: route output before packaging
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gut_batch_records
• Sources: cenis-et-al-2015-silkworm-gut; iso-2062-2009

Waste flows

Silkworm tissue waste (silkworm_tissue_waste)

Biological tissue remaining after silk-gland removal and sent to waste management is recorded as one specific waste stream.

• Selected flow: Silkworm tissue waste
• Flow property / unit: Mass / kg
• Amount rule: Weighed wet mass crossing the waste-management boundary, with dry-matter content retained when measured
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry silkworm gut output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gut_batch_records
• Sources: cenis-et-al-2015-silkworm-gut

Spent silkworm-gut acetic-acid bath (silkworm_acidic_wastewater)

The spent aqueous acetic-acid bath sent to treatment is recorded separately from biological tissue waste.

• Selected flow: Spent silkworm-gut acetic-acid bath
• Flow property / unit: Mass / kg
• Amount rule: Measured bath mass discharged to treatment, or measured volume converted with recorded density
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg net dry silkworm gut output
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_gut_batch_records
• Sources: cenis-et-al-2015-silkworm-gut; ifc-textiles-ehs-2007

Elementary flows

7. Allocation and Co-product Handling

rule_id	Applies to	Rule	source_ids
allocation_avoid_by_subdivision	all routes	Subdivide route-specific processes and separately meter batches, utilities and outputs before applying allocation.	iso-14044-2006
allocation_recovered_silk	recovered silk waste	When recovered silk waste is transferred as a useful product, keep it as a product output and document the allocation relationship; material sent to waste management remains a Waste flow and receives no product credit.	iso-14044-2006; yin-et-al-2021-spun-silk
allocation_recovered_sericin	recovered sericin	When saleable sericin is recovered, first subdivide the recovery operation; if shared burdens cannot be subdivided, use a documented physical relationship that reflects the process, and use economic allocation only when no defensible physical relationship exists.	iso-14044-2006; eu-textiles-bref-2023
allocation_no_unreported_credit	all wastes and co-products	Do not apply avoided-burden, substitution or recycling credits unless the study explicitly models the additional function and reports the method, substituted product, geography and sensitivity result.	iso-14044-2006

8. Foreground Data Collection, Calculation, and Quality Rules

Data Collection Protocols

protocol_id	process_id	flow_role	record_type	raw_fields	collection_method	unit	frequency	temporal_coverage	site_scope	aggregation_rule	quality_evidence
cp_filament_batch_records	silk_filament_yarn_forming	material, product and silk-waste mass	scale tickets and batch records	batch_id; row_id; gross_mass; tare_mass; moisture_or_conditioning_basis; accepted_output_mass; recovered_mass; discarded_mass	Calibrated scale linked to production and disposition records	kg	Each batch	Representative continuous 12-month period or all batches in the declared shorter period	All included filament-yarn lines	Sum by row_id and batch; subtract tare and returned material; normalize with calc_normalize_reference	Calibration records, batch genealogy, recovery acceptance and waste transfer notes
cp_filament_electricity_meter	silk_filament_yarn_forming	medium-voltage grid electricity	interval meter or submeter	meter_id; voltage; supplier; interval_start; interval_end; opening_kwh; closing_kwh; excluded_load_kwh	Calibrated meter; subtract documented non-route loads	kWh	Each interval and monthly reconciliation	Same period as product batches	All included filament-yarn equipment	Sum route kWh and allocate shared measured loads with disclosed driver	Meter calibration, bills and load-allocation worksheet
cp_degumming_batch_records	silk_waste_degumming_dressing	silk waste, sodium carbonate, fibre output, recovered sericin and wastewater	scale, recipe and batch records	batch_id; row_id; gross_mass; tare_mass; moisture_basis; recipe_issue_mass; output_mass; wastewater_mass_or_volume; density; destination	Calibrated scales and batch recipe/disposition records	kg	Each batch	Representative continuous 12-month period or all batches in the declared shorter period	All included degumming and dressing lines	Sum each row separately; convert wastewater volume only with recorded density	Calibration, recipe approval, batch genealogy, discharge and transfer records
cp_degumming_water_meter	silk_waste_degumming_dressing	process water	water meter	meter_id; opening_volume; closing_volume; density; batch_id; reused_water_mass	Calibrated meter with batch assignment	kg	Each batch or metering interval	Same period as degumming batches	All included wet-process lines	Fresh input only; report reused internal water separately without double counting	Meter calibration and water balance
cp_degumming_steam_meter	silk_waste_degumming_dressing	supplied steam	steam meter or supplier record	meter_id; steam_mass; pressure; condensate_return_mass; batch_id	Calibrated steam meter or reconciled supplier record	kg	Each batch or metering interval	Same period as degumming batches	All included wet-process lines	Sum delivered steam crossing the boundary; disclose condensate-return convention	Meter calibration, steam balance and invoice reconciliation
cp_degumming_electricity_meter	silk_waste_degumming_dressing	medium-voltage grid electricity	interval meter or submeter	meter_id; voltage; supplier; interval_start; interval_end; opening_kwh; closing_kwh; excluded_load_kwh	Calibrated meter; subtract documented non-route loads	kWh	Each interval and monthly reconciliation	Same period as degumming batches	All included wet-process and dressing equipment	Sum route kWh and allocate shared measured loads with disclosed driver	Meter calibration, bills and allocation worksheet
cp_spinning_batch_records	spun_silk_spinning	degummed fibre, spun silk and silk-waste mass	scale tickets and batch records	batch_id; row_id; gross_mass; tare_mass; moisture_or_conditioning_basis; accepted_output_mass; discarded_mass	Calibrated scale linked to spinning and disposition records	kg	Each batch	Representative continuous 12-month period or all batches in the declared shorter period	All included spinning lines	Sum by row_id and batch; subtract tare; normalize with calc_normalize_reference	Calibration, batch genealogy, quality release and waste transfer notes
cp_spinning_electricity_meter	spun_silk_spinning	medium-voltage grid electricity	interval meter or submeter	meter_id; voltage; supplier; interval_start; interval_end; opening_kwh; closing_kwh; excluded_load_kwh	Calibrated meter; subtract documented non-route loads	kWh	Each interval and monthly reconciliation	Same period as spinning batches	All included spinning equipment	Sum route kWh and allocate shared measured loads with disclosed driver	Meter calibration, bills and allocation worksheet
cp_gassing_batch_records	spun_silk_gassing	yarn input, yarn output and captured silk waste	scale tickets and batch records	batch_id; row_id; gross_mass; tare_mass; conditioning_basis; accepted_output_mass; captured_waste_mass	Calibrated scale linked to gassing and disposition records	kg	Each batch	All gassed batches in the declared period	All included gassing lines	Sum each row separately and normalize with calc_normalize_reference	Calibration, batch genealogy, quality release and waste transfer notes
cp_gassing_gas_meter	spun_silk_gassing	gaseous natural gas	fuel meter or invoice	meter_id; raw_volume_or_mass; temperature; pressure; conversion_factor; assigned_batch; supplier	Calibrated meter or supplier record with site-specific conversion	kg	Each interval and monthly reconciliation	Same period as gassed batches	All included gassing burners	Convert raw record to kg using retained measured conditions; allocate shared use with disclosed driver	Meter calibration, gas bills and conversion worksheet
cp_gassing_electricity_meter	spun_silk_gassing	medium-voltage grid electricity	interval meter or submeter	meter_id; voltage; supplier; opening_kwh; closing_kwh; excluded_load_kwh	Calibrated meter; subtract documented non-route loads	kWh	Each interval and monthly reconciliation	Same period as gassed batches	Gassing drive, control and assigned extraction equipment	Sum route kWh and allocate shared measured loads with disclosed driver	Meter calibration, bills and allocation worksheet
cp_gassing_air_monitoring	spun_silk_gassing	carbon monoxide and fine particulate emissions	stack or workplace-exhaust monitoring and operating log	sampling_point; pollutant; concentration; gas_flow; duration; abatement_state; batch_id; detection_limit	Accredited or documented site method applied downstream of included abatement	kg	Representative operating campaigns and after material change	Covers normal, start-up and shut-down conditions in the declared period	Every included gassing exhaust	Calculate emitted mass from measured concentration, flow and duration; report below-detection treatment	Method, calibration, detection limits, lab report and operating log
cp_gut_batch_records	silkworm_gut_forming	silk gland, gut product, tissue waste and spent acidic bath	scale, bath and batch records	batch_id; row_id; gross_mass; tare_mass; acid_bath_mass_or_volume; density; product_dry_mass; tissue_wet_mass; destination	Calibrated scales and batch/disposition records	kg	Each batch	All batches in the declared production period	All included gut-forming stations	Sum each row separately; retain wet/dry basis; normalize with calc_normalize_reference	Calibration, batch genealogy, product quality and waste-transfer records
cp_gut_water_meter	silkworm_gut_forming	process water	water meter or weighed addition	batch_id; water_volume_or_mass; density; reused_water_mass	Calibrated meter or scale	kg	Each batch	Same period as gut batches	All included bath and rinse stations	Fresh input only; convert volume only with recorded density	Meter or scale calibration and bath sheet
cp_gut_acid_records	silkworm_gut_forming	acetic acid	supplier certificate and weighed solution issue	batch_id; solution_mass; certified_acetic_acid_mass_fraction; returned_solution_mass	Weighed issue reconciled to supplier concentration	kg active acetic acid	Each batch and supplier lot	Same period as gut batches	All included acid baths	Apply calc_acetic_acid_active_mass; do not combine with process water	Scale calibration, certificate of analysis and batch recipe

Calculation Rules

rule_id	Applies to	Formula or rule	Inputs	Output	source_ids
calc_normalize_reference	every inventory row	normalized_amount = route-period row amount / route-period net dry conforming product mass	row amount; net dry conforming product mass	amount per 1 kg reference product	iso-14044-2006
calc_net_dry_product_mass	yarn or gut product	net_dry_mass = gross conditioned mass - packaging tare - measured water mass above the declared dry basis	gross mass; tare; moisture or conditioning result	kg net dry product	iso-2060-1994
calc_acetic_acid_active_mass	silkworm_gut_acetic_acid	active_acetic_acid_mass = net solution mass × supplier-certified acetic-acid mass fraction	solution mass; certified mass fraction; returned solution mass	kg active acetic acid	cenis-et-al-2015-silkworm-gut
calc_direct_air_emission	gassing elementary outputs	emitted_mass = measured concentration × measured exhaust flow × operating duration, with unit conversion and documented below-detection handling	concentration; exhaust flow; duration; abatement state	kg pollutant emitted	ifc-textiles-ehs-2007
calc_route_mass_balance	each route process	mass_balance_gap = total measured mass inputs - total measured product, waste and measured emission outputs, reported with moisture and accumulation terms	all mass inputs; all mass outputs; moisture change; stock change	disclosed kg and percent mass-balance gap	iso-14044-2006

Data Quality Requirements

requirement_id	Applies to	Requirement	Evidence
dq_identity	every flow card	Preserve row_id, flow direction, flow type, selected flow name and confirmed UUID; an unresolved UUID shall remain explicit and shall not be replaced by a broad candidate.	Flow list/get verification record and manifest review metadata
dq_route	product and process map	Route, starting material, sericin condition, gassing status and included processes shall be batch-traceable.	Product specification and batch genealogy
dq_measurement	foreground amounts	Use calibrated meters or scales and retain raw records, tare, unit conversion, allocation driver and detection-limit treatment.	Calibration certificates, meter exports, scale tickets and calculation workbook
dq_temporal	published average	Cover a representative continuous 12-month period; a shorter campaign is allowed only with production dates, batch coverage and seasonality limitation disclosed.	Production calendar and completeness calculation
dq_completeness	all processes	Reconcile production, material, chemical, utility, waste, wastewater and direct-emission records; explain every omitted or below-detection exchange.	Route mass balance, utility reconciliation and omission log
dq_external_links	upstream datasets	Match input identity, geography, technology, voltage, steam pressure and fuel supply state as closely as available; disclose every proxy and mismatch.	Upstream dataset metadata and proxy justification

9. Validation Rules

rule_id	Applies to	Rule	source_ids
validation_reference_flow	reference product	The data package shall normalize to 1 kg net dry product and use confirmed Spun Silk UUID 6c639604-29e8-44b6-be18-4e0ad97fdef8 for the representative spun-silk product; another covered route shall use an exact reviewed product UUID before release.	unsd-cpc-3-0-2025; iso-14044-2006
validation_route_declaration	process map	Exactly one covered product route shall be declared, and every route-required process plus every actually used optional process shall be present.	eu-textiles-bref-2023; yin-et-al-2021-spun-silk; cenis-et-al-2015-silkworm-gut
validation_atomic_inventory	all inventory rows	Every exchange shall have one row_id, one direction, one flow type and one specific selected flow; combined utilities, chemicals, packaging, wastes or emissions fail validation.	eu-textiles-bref-2023; ifc-textiles-ehs-2007
validation_foreground_amounts	all foreground rows	Every amount shall come from a retained foreground record or an explicit calculation from collected records; this PCR supplies no guessed default amount or reasoned-estimate range.	iso-14044-2006
validation_wet_route	silk-waste degumming	A wet-route package shall contain silk waste, process water, each actual chemical, steam when transferred, electricity, degummed fibre, recovered sericin when produced, and route-specific wastewater, with all amounts separately reconciled.	eu-textiles-bref-2023; ifc-textiles-ehs-2007; yin-et-al-2021-spun-silk
validation_gassing	gassing route	When gassing is included, natural gas, electricity, yarn input/output, captured silk waste, fossil carbon monoxide and fine particulate emissions shall be measured or explicitly documented below detection after abatement.	yin-et-al-2021-spun-silk; ifc-textiles-ehs-2007
validation_gut_route	silkworm-gut forming	A gut-route package shall separately record silk gland, process water, active acetic acid, gut output, tissue waste and spent acidic bath and shall declare diameter, length and tensile-quality evidence.	cenis-et-al-2015-silkworm-gut; iso-2062-2009
validation_mass_balance	each route	The route mass balance shall report input, product, recovered material, waste, wastewater, measured emissions, moisture change, stock change and residual gap on consistent bases.	iso-14044-2006
validation_uuid_resolution	release readiness	Every route-required unresolved flow identity shall be resolved or accepted through formal review before active or published release; the confirmed reference product, Mass property and Units of mass group identities shall remain unchanged unless superseded by documented public-record review; semantically rejected candidates shall not be substituted.	unsd-cpc-3-0-2025

10. Published Dataset Profile

Field	Value
dataset_role	Foreground production dataset for one declared CPC 26310 silk-yarn or silkworm-gut route
downstream_use	secondary_dataset; background_dataset after review and publication
allowed_use	Product-footprint, LCA and supply-chain modelling when route, geography, period, product specification and upstream links match the study
excluded_use	Undeclared average across filament yarn, spun silk and silkworm gut; proxy for raw silk, woven fabric, dyed or weighted silk, finished sutures, or a route with materially different wet processing or energy supply
required_metadata	PCR id and version; product route; product and flow UUIDs; geography; reference period; silk source/species where known; sericin condition; yarn construction or gut dimensions; linear density or diameter; twist where applicable; moisture basis; process list; utility supply scenarios; allocation method; data owner and review status
required_quality_disclosure	Foreground coverage; meter and scale calibration; mass-balance gap; proxy datasets; unresolved identities; below-detection treatment; wastewater destination; abatement state; allocation sensitivity; excluded processes
update_trigger	Change in starting material, route, degumming recipe, gassing technology, energy supply, product specification, allocation method, wastewater treatment, abatement, geography, or a material change in measured inventory

11. Data Sources

Source id	Type	Reference	Used for
unsd-cpc-3-0-2025	Official guidance (official_guidance)	United Nations Statistics Division, CPC Version 3.0 Explanatory Notes, code 26310, 30 June 2025, https://unstats.un.org/unsd/classifications/Econ/Download/In%20Text/CPC_Ver_3.0_Exp_Notes_30Jun2025.pdf (retrieved 2026-08-12)	Product-category scope and classification identity
eu-textiles-bref-2023	Official guidance (official_guidance)	European Commission Joint Research Centre, Best Available Techniques Reference Document for the Textiles Industry, 2023, https://bureau-industrial-transformation.jrc.ec.europa.eu/sites/default/files/2023-01/TXT_BREF_2023_for_publishing%20ISSN%201831-9424_final_1_revised.pdf (retrieved 2026-08-12)	Silk input boundary, yarn processing, silk scouring, utilities, wastewater and monitoring
ifc-textiles-ehs-2007	Official guidance (official_guidance)	IFC / World Bank Group, Environmental, Health, and Safety Guidelines for Textile Manufacturing, 30 April 2007, https://www.ifc.org/content/dam/ifc/doc/2000/2007-textiles-manufacturing-ehs-guidelines-en.pdf (retrieved 2026-08-12)	Wastewater, energy, air-emission and monitoring requirements
iso-1144-2016	Standard (standard)	ISO 1144:2016, Textiles — Universal system for designating linear density (Tex System), https://www.iso.org/standard/70774.html (retrieved 2026-08-12)	Linear-density declaration and unit convention
iso-2060-1994	Standard (standard)	ISO 2060:1994, Textiles — Yarn from packages — Determination of linear density (mass per unit length) by the skein method, https://www.iso.org/standard/6837.html (retrieved 2026-08-12)	Yarn mass-per-length measurement and conditioning declaration
iso-2062-2009	Standard (standard)	ISO 2062:2009, Textiles — Yarns from packages — Determination of single-end breaking force and elongation at break using constant rate of extension, https://www.iso.org/standard/45642.html (retrieved 2026-08-12)	Yarn and gut tensile-quality evidence
iso-14044-2006	Standard (standard)	ISO 14044:2006, Environmental management — Life cycle assessment — Requirements and guidelines, https://www.iso.org/standard/38498.html (retrieved 2026-08-12)	Boundary, inventory, allocation, normalization and data-quality method
yin-et-al-2021-spun-silk	Literature (literature)	Yin, R. et al., Cleaner Production of Mulberry Spun Silk Yarns via a Shortened and Gassing-free Production Route, Journal of Cleaner Production, DOI: 10.1016/j.jclepro.2020.123690	Silk-waste degumming, dressing, spinning, gassing and waste-flow decomposition
cenis-et-al-2015-silkworm-gut	Literature (literature)	Cenis, J. L. et al., Mechanical behaviour and formation process of silkworm silk gut, Soft Matter 11 (2015) 8981–8991, DOI: 10.1039/C5SM01877C	Silk-gland, acidic-bath and stretching route for silkworm gut