Metallized yarn

1. Scope and Applicability

This PCR applies to factory-gate metallized yarn classified as CPC 3.0 code 27993. It covers textile yarn or a yarn-forming textile component that is covered with metal or combined with a metal monofilament, thread, strip, or comparable discrete metallic component and is sold as yarn for downstream textile manufacture. The foreground package shall declare the textile substrate, metal species, metal-incorporation route, yarn construction, surface or protective coating, linear density, metal mass fraction, and saleable state.

The PCR excludes uncombined textile yarn, bare metal wire sold as wire, woven fabrics made from metal thread or metallized yarn, finished garments and other downstream textile articles, and mixtures whose metallic component or manufacturing route is not disclosed. The reference inventory provides two route archetypes supported by the evidence: direct metal coating of a textile yarn and mechanical combination of a metal monofilament with a base yarn. A producer using another route shall preserve the same measurement, boundary, allocation, data-quality, and validation rules while recording every actual material, utility, waste, and elementary exchange as a separate atomic row.

2. Product Category Identity

Field	Value
canonical_pcr_id	pcr.food-products-beverages-and-tobacco-textiles-apparel-and-leather-products.textile-articles-other-than-apparel.metallized-yarn
classification_refs	CPC 3.0: 27993, Metallized yarn
covered_products	Metal-coated textile yarn; textile yarn combined with a metal monofilament, thread, or strip; metallized yarn supplied for downstream weaving, knitting, embroidery, or other textile manufacture.
excluded_products	Uncombined textile yarn; bare metal wire sold as wire; woven fabrics of metal thread or metallized yarn; non-metallic gimped yarn; finished fabrics, garments, and other downstream articles; products with an undeclared metal or substrate.
representative_product	Saleable metallized yarn wound for industrial textile use, represented by either aluminium-coated polyester filament yarn or polyester yarn mechanically combined with stainless steel monofilament.
production_route	Route-specific at-plant production: direct metal coating by a declared deposition or plating technique, or mechanical twisting/wrapping of one declared metal monofilament with one declared textile base yarn, followed by in-line inspection and winding.
market_state	Finished, dry, saleable yarn at the factory gate; net yarn mass excludes cones, spools, reusable carriers, and transport packaging.

3. Reference Flow

Field	Value
What	Metallized yarn that supplies a declared metallic component within a textile-yarn construction for downstream textile manufacture.
How much	1 kg net dry mass of saleable metallized yarn at the factory gate.
How well	Conforms to the producer's declared substrate, metal species, metal mass fraction, yarn construction, linear density, coating state, and acceptance specification.
How long or cycle	One completed production batch; no service duration is assigned to the intermediate product.
reference_flow_link	The functional unit is realized by the reference product flow below after rejection and rework are accounted for.

Field	Value
Reference amount	1 kg net dry metallized yarn
Reference product flow	Metallized yarn fae82400-7c2c-4779-a516-2c6dcdbee472
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	textile substrate and fibre composition; metal species and form; metal-incorporation route; yarn construction; linear density and test condition; metal mass fraction; protective coating or finish; moisture condition; production geography; production period; saleable state; exclusion of cone, spool, carrier, and transport-packaging mass

When constructing a foreground data package, the items listed in Required qualifiers must be declared in dataset metadata, process notes, reference flow comment, product description, or an equivalent data package field. Missing required qualifiers make the reference flow definition incomplete for that data package.

4. Measurement and Unit Rules

rule_id	Applies to	Required property	Required unit	Rule
reference_mass	Reference product	Mass 93a60a56-a3c8-11da-a746-0800200b9a66	kg	Report exactly 1 kg net dry saleable yarn. Exclude cones, spools, reusable carriers, and transport packaging; disclose the moisture-conditioning basis used for weighing.
material_mass	Textile substrate, metal, finished yarn, rejects, and scrap	Mass	kg	Measure by calibrated scale or derive from reconciled batch issue and return records. Preserve each material identity and do not combine different metals, substrates, or waste streams.
electricity_use	Electricity consumed by coating, twisting/wrapping, inspection, and winding	Energy	kWh	Use route-specific submetered electricity where available; otherwise allocate a documented shared meter by operating time, rated load, or another physical driver before normalization.
linear_density_disclosure	Saleable metallized yarn	Linear density	tex	Report the test method, conditioning state, number of determinations, and batch result used for product acceptance; do not convert linear density into product mass without the measured yarn length and matching condition.

5. System Boundary

The foreground boundary begins when declared textile yarn, metallic feedstock or monofilament, and other route-specific inputs are received by the metallized-yarn producer. It includes route-specific metal incorporation, twisting or wrapping when applicable, in-line inspection, winding, rework, and handling of rejects generated by those operations. Production of textile yarn, aluminium, stainless steel, electricity, and other purchased inputs remains upstream and requires linked upstream datasets. Downstream weaving, knitting, embroidery, garment manufacture, use, and end-of-life are outside the foreground boundary.

Boundary Abstraction

Field	Value
declared_starting_condition	Received textile substrate and metallic feedstock at the metallized-yarn manufacturing site, with supplier, composition, mass, moisture condition, and upstream dataset identifiers declared.
starting_condition_role	Upstream product input to the foreground metallized-yarn operation.
product_classification_scope	CPC 3.0 code 27993 only; downstream woven fabric and other textile articles are outside this PCR.
recursive_input_rule	If metallized yarn is consumed as an input to produce the reference metallized yarn, record it once as an upstream product input with its own dataset and mass; do not recursively reopen its production inside the same foreground process.
upstream_dataset_requirement	Provide product-specific or representative upstream datasets for each textile substrate, each metal feedstock, electricity supply, and every other purchased input actually used.
disclosure	Disclose the metal species and form, substrate composition, incorporation technique, protective finish, rework loop, yield definition, excluded packaging or carrier mass, site, period, and any shared-process allocation.

Normative Rules

rule_id	Applies to	Rule	source_ids
boundary_route_specific	Foreground process map	Include only the declared route, but include every operation at the producing site from received inputs through accepted wound yarn, including route-specific coating or combination, rework, inspection, and reject handling.	repon-mikucioniene-2021; jrc-textiles-bref-2023
boundary_upstream_inputs	Purchased material and energy inputs	Keep upstream production outside the foreground boundary and link a dataset for each separately identified textile substrate, metal, and energy carrier.	ec-pef-2021-2279
boundary_no_hidden_wet_steps	Wet plating, cleaning, or coating steps when present	If the declared route uses water, chemicals, solvents, or wet treatment, add each actual chemical input, water input, wastewater output, sludge output, and substance-specific direct emission as an atomic exchange; absence of such steps must be documented rather than represented by a zero-value placeholder.	jrc-textiles-bref-2023

6. Process Inventory Structure

Process Map

process_id	process_name	inclusion	inclusion_condition	role	quantitative_reference
metal_coating	Direct metal coating, inspection, and winding	conditional	Include when metal is deposited or plated directly onto the textile yarn.	Creates accepted metal-coated yarn from one declared textile substrate and one declared metal species.	1 kg accepted metallized yarn from this route
metal_filament_combination	Metal monofilament combination, inspection, and winding	conditional	Include when a metal monofilament is twisted or wrapped with a base textile yarn.	Creates accepted combined metallic yarn from one declared base yarn and one declared metal monofilament.	1 kg accepted metallized yarn from this route

Process: Direct metal coating, inspection, and winding (metal_coating)

Inputs

Product flows

Polyester filament yarn substrate (polyester_yarn_input_coating)

Undyed polyester filament yarn crosses the foreground boundary as the textile substrate for the representative direct-coating route. Its issued dry mass is obtained from batch issue and return records.

• Selected flow: Polyester filament yarn, undyed
• Flow property / unit: Mass / kg
• Amount rule: Foreground dry mass issued to the coating batch, net of documented returns
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg accepted metallized yarn from metal_coating
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_metal_coating_batch
• Sources: repon-mikucioniene-2021

Aluminium feedstock (aluminium_input_coating)

Aluminium crosses the foreground boundary as the representative metal deposited onto the polyester yarn. Record actual net batch consumption and retain metal grade and supplier evidence.

• Selected flow: Aluminium, primary, unwrought
• Flow property / unit: Mass / kg
• Amount rule: Foreground aluminium issued minus recovered clean return, measured for the batch
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg accepted metallized yarn from metal_coating
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_metal_coating_batch
• Sources: repon-mikucioniene-2021

Medium-voltage electricity for metal coating (electricity_input_coating)

Electricity crosses the foreground boundary to operate deposition or plating equipment, vacuum equipment when used, inspection, and winding for this route.

• Selected flow: Electricity, medium voltage
• Flow property / unit: Energy / kWh
• Amount rule: Route-specific submeter reading or documented physical allocation of the shared meter
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted metallized yarn from metal_coating
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_metal_coating_energy
• Sources: jrc-textiles-bref-2023

Waste flows

Elementary flows

Outputs

Product flows

Accepted metallized yarn from direct coating (metallized_yarn_output_coating)

Accepted coated yarn is the route-specific reference product after in-line inspection, rework accounting, and winding. Its net dry mass excludes the cone, spool, carrier, and transport packaging.

• Selected flow: Metallized yarn fae82400-7c2c-4779-a516-2c6dcdbee472
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: exactly 1 kg accepted net dry yarn by reference-flow definition
• Value mode: Fixed value (fixed_value)
• Specificity: Product-specific (product_specific)
• Normalization basis: reference flow
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Identity reference (identity_reference)
• Sources:

Waste flows

Off-spec aluminium-coated polyester yarn (offspec_yarn_output_coating)

Rejected coated yarn leaves the process as one separately weighed waste stream unless it is demonstrably returned to the same batch as rework.

• Selected flow: Off-spec aluminium-coated polyester yarn
• Flow property / unit: Mass / kg
• Amount rule: Foreground rejected mass not returned as documented rework
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted metallized yarn from metal_coating
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_metal_coating_batch
• Sources:

Elementary flows

Process: Metal monofilament combination, inspection, and winding (metal_filament_combination)

Inputs

Product flows

Polyester filament base yarn (polyester_yarn_input_combination)

Undyed polyester filament yarn crosses the foreground boundary as the base yarn around which the representative stainless steel monofilament is mechanically combined.

• Selected flow: Polyester filament yarn, undyed
• Flow property / unit: Mass / kg
• Amount rule: Foreground dry mass issued to the combination batch, net of documented returns
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg accepted metallized yarn from metal_filament_combination
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_metal_combination_batch
• Sources: repon-mikucioniene-2021

Stainless steel monofilament (stainless_steel_monofilament_input)

One declared stainless steel monofilament crosses the foreground boundary as the metallic component twisted or wrapped with the polyester base yarn.

• Selected flow: Stainless steel monofilament
• Flow property / unit: Mass / kg
• Amount rule: Foreground dry mass issued to the combination batch, net of documented returns
• Value mode: Foreground record (foreground_record)
• Specificity: Route-specific (route_specific)
• Normalization basis: per 1 kg accepted metallized yarn from metal_filament_combination
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_metal_combination_batch
• Sources: repon-mikucioniene-2021

Medium-voltage electricity for twisting and winding (electricity_input_combination)

Electricity crosses the foreground boundary to operate twisting or wrapping, in-line inspection, and winding equipment for this route.

• Selected flow: Electricity, medium voltage
• Flow property / unit: Energy / kWh
• Amount rule: Route-specific submeter reading or documented physical allocation of the shared meter
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted metallized yarn from metal_filament_combination
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_metal_combination_energy
• Sources: jrc-textiles-bref-2023

Waste flows

Elementary flows

Outputs

Product flows

Accepted metallized yarn from monofilament combination (metallized_yarn_output_combination)

Accepted combined yarn is the route-specific reference product after in-line inspection, rework accounting, and winding. Its net dry mass excludes the cone, spool, carrier, and transport packaging.

• Selected flow: Metallized yarn fae82400-7c2c-4779-a516-2c6dcdbee472
• Flow property / unit: Mass 93a60a56-a3c8-11da-a746-0800200b9a66 / kg
• Amount rule: exactly 1 kg accepted net dry yarn by reference-flow definition
• Value mode: Fixed value (fixed_value)
• Specificity: Product-specific (product_specific)
• Normalization basis: reference flow
• Basis kind: Reference flow (reference_flow)
• Evidence kind: Identity reference (identity_reference)
• Sources:

Waste flows

Off-spec stainless-steel-filament polyester yarn (offspec_yarn_output_combination)

Rejected combined yarn leaves the process as one separately weighed waste stream unless it is demonstrably returned to the same batch as rework.

• Selected flow: Off-spec stainless-steel-filament polyester yarn
• Flow property / unit: Mass / kg
• Amount rule: Foreground rejected mass not returned as documented rework
• Value mode: Foreground record (foreground_record)
• Specificity: Site-specific (site_specific)
• Normalization basis: per 1 kg accepted metallized yarn from metal_filament_combination
• Basis kind: Process output (process_output)
• Evidence kind: Collected record (collected_record)
• Collection protocol: cp_metal_combination_batch
• Sources:

Elementary flows

7. Allocation and Co-product Handling

rule_id	Applies to	Rule	source_ids
allocation_avoid	Route-specific production batch	First separate route, product, and rework records so that inputs, energy, accepted output, and rejects are directly assigned without allocation.	ec-pef-2021-2279
allocation_physical	Shared coating, twisting, inspection, winding, or utility records	When direct assignment is not possible, allocate by a documented physical relationship such as route-specific operating time, metered energy, or dry mass throughput; economic allocation is permitted only when no defensible physical relationship exists and must be disclosed.	ec-pef-2021-2279
allocation_rework	Internal rework	Keep reworked yarn inside the producing batch and count only its additional measured material and energy once; do not report the same reworked mass as both product and waste.	ec-pef-2021-2279
allocation_scrap	Off-spec yarn leaving the foreground boundary	Report the measured reject as a waste output. Any recycling credit or substituted-product claim belongs to an explicitly declared downstream scenario and shall not reduce the foreground inventory silently.	ec-pef-2021-2279

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_metal_coating_batch	metal_coating	substrate input, aluminium input, accepted output, reject output, and rework	batch material record	batch_id; substrate_item; substrate_mass; aluminium_item; aluminium_issued_mass; aluminium_return_mass; accepted_net_dry_mass; reject_mass; rework_mass; moisture_condition	Calibrated scale records reconciled to issue, return, production, quality, and waste tickets.	kg	every batch	Representative continuous 12-month period or all batches in a shorter declared campaign	Every site included in the dataset	Sum non-overlapping batch records, keep rework internal, then normalize by accepted net dry mass.	Calibration certificate; signed batch record; material issue and return tickets; reject disposition; moisture-conditioning record.
cp_metal_coating_energy	metal_coating	coating, inspection, and winding electricity	meter record	meter_id; start_time; end_time; start_reading; end_reading; route_runtime; shared_meter_driver; batch_id	Read a route submeter; if shared, retain meter total and the physical allocation calculation.	kWh	every batch or meter interval	Same period and site coverage as material records	Every coating line included in the dataset	Subtract verified non-production loads when separately metered, allocate shared use by the declared physical driver, and normalize by accepted net dry mass.	Meter identification; calibration or utility reconciliation; operating log; allocation workbook.
cp_metal_combination_batch	metal_filament_combination	base-yarn input, monofilament input, accepted output, reject output, and rework	batch material record	batch_id; base_yarn_item; base_yarn_mass; metal_monofilament_item; metal_monofilament_mass; accepted_net_dry_mass; reject_mass; rework_mass; moisture_condition	Calibrated scale records reconciled to issue, return, production, quality, and waste tickets.	kg	every batch	Representative continuous 12-month period or all batches in a shorter declared campaign	Every site included in the dataset	Sum non-overlapping batch records, keep rework internal, then normalize by accepted net dry mass.	Calibration certificate; signed batch record; issue and return tickets; reject disposition; moisture-conditioning record.
cp_metal_combination_energy	metal_filament_combination	twisting, inspection, and winding electricity	meter record	meter_id; start_time; end_time; start_reading; end_reading; route_runtime; shared_meter_driver; batch_id	Read a route submeter; if shared, retain meter total and the physical allocation calculation.	kWh	every batch or meter interval	Same period and site coverage as material records	Every combination line included in the dataset	Subtract verified non-production loads when separately metered, allocate shared use by the declared physical driver, and normalize by accepted net dry mass.	Meter identification; calibration or utility reconciliation; operating log; allocation workbook.

Calculation Rules

rule_id	Applies to	Formula or rule	Inputs	Output	source_ids
calc_normalized_exchange	Every collected material, energy, and waste exchange	normalized exchange = route-period exchange / accepted net dry metallized yarn from the same route and period	non-overlapping exchange total; accepted net dry yarn mass	kg/kg or kWh/kg as applicable	ec-pef-2021-2279
calc_metal_consumption	Direct-coating metal input	net metal input = issued metal - verified clean metal return; do not subtract metal contained in waste that leaves the foreground boundary	issued metal mass; clean return mass	kg net metal input	ec-pef-2021-2279
calc_batch_mass_balance	Each route and reporting period	mass-balance difference = total material inputs - accepted yarn output - measured material waste outputs - verified clean returns; investigate and disclose the residual rather than forcing it to zero	substrate and metal inputs; accepted output; waste outputs; clean returns	kg and percent of total material input	ec-pef-2021-2279
calc_metal_mass_fraction	Reference product qualifier	metal mass fraction = measured metal mass in accepted yarn / accepted net dry yarn mass, using batch mass reconciliation or a documented product-composition test	accepted-product metal mass; accepted net dry yarn mass	kg metal/kg yarn	repon-mikucioniene-2021

Data Quality Requirements

requirement_id	Applies to	Requirement	Evidence
dq_identity	Reference product and all inputs	Retain exact substrate composition, metal species and form, route, yarn construction, linear density, coating or finish, and Tiangong UUID where confirmed.	Product specification; bill of materials; state-100 UUID evidence; supplier declaration.
dq_temporal	Foreground records	Use one representative continuous 12-month period unless the campaign is shorter; disclose the period, shutdowns, and excluded batches.	Production calendar; batch register; meter coverage report.
dq_completeness	Each included route	Reconcile material issue, return, accepted output, rework, rejects, and metered energy; document any route-specific water, chemical, solvent, wastewater, sludge, or direct-emission exchange that actually occurs.	Signed reconciliation; waste tickets; meter reconciliation; environmental monitoring records.
dq_measurement	Mass, energy, and linear density	Use calibrated or utility-reconciled instruments and retain method, condition, frequency, and uncertainty or tolerance information.	Calibration certificates; test report; utility invoice; instrument log.
dq_representativeness	Multi-line or multi-site dataset	Include all lines and sites claimed by the dataset or document a production-weighted sampling and aggregation method.	Line/site production totals; sampling plan; aggregation workbook.
dq_uuid_resolution	Unresolved inventory flow identities	Do not assign an inventory UUID until the named atomic exchange is confirmed independently by hybrid retrieval and a state-100 direct read.	Manifest row-level candidate record and direct-read evidence.

9. Validation Rules

rule_id	Applies to	Rule	source_ids
validate_reference_identity	Reference flow	The product flow UUID shall resolve at state 100 to Product flow, base name Metallized yarn, CPC 27993, quantitative reference Mass, and reference unit kg.	unsd-cpc-3-2025
validate_reference_amount	Reference flow	Accepted output shall equal exactly 1 kg net dry yarn; carrier and packaging mass shall be excluded and moisture condition disclosed.	ec-pef-2021-2279
validate_route_exclusivity	Process map	Include metal_coating, metal_filament_combination, or both only when production records show the corresponding route; do not merge route inventories before route-level mass and energy reconciliation.	repon-mikucioniene-2021
validate_atomic_flows	Inventory rows	Every selected flow shall be one concrete exchange. Different metals, textile substrates, chemicals, energy carriers, waste streams, and emitted substances shall remain separate rows.	jrc-textiles-bref-2023
validate_mass_balance	Each route and period	Report the calculated mass-balance residual and investigate material discrepancies against issue, return, rework, reject, and accepted-output records.	ec-pef-2021-2279
validate_uuid_evidence	Inventory UUIDs	Reject an inventory UUID that lacks both hybrid-retrieval evidence and an exact state-100 direct read for the selected atomic flow.
validate_bilingual_alignment	English and Chinese PCR renderings	The ordered process ids, row ids, rule ids, controlled tokens, source ids, and UUIDs shall match exactly across languages.

10. Published Dataset Profile

Field	Value
dataset_role	Foreground metallized-yarn production data package and publishable unit-process dataset.
downstream_use	secondary_dataset; background_dataset
allowed_use	LCA of downstream yarn processing, weaving, knitting, embroidery, textile products, and route-specific supply-chain studies when the required qualifiers and representativeness match.
excluded_use	Bare metal wire, uncombined textile yarn, woven fabric, garments, products with undisclosed metal or substrate, or comparisons that ignore different metal species, metal fractions, coating routes, or yarn constructions.
required_metadata	PCR id and version; CPC 27993; product-flow and Mass UUIDs; textile substrate; metal species and form; incorporation route; yarn construction; linear density; metal mass fraction; coating or finish; moisture condition; geography; period; route share; allocation; net-mass exclusions; unresolved UUIDs.
required_quality_disclosure	Record coverage; calibration and meter reconciliation; mass-balance residual; route-level allocation; rework and reject treatment; upstream dataset selection; missing route-specific exchanges; UUID verification state; data limitations.
update_trigger	Change in substrate, metal species or form, metal fraction, deposition/plating or combination route, protective finish, major equipment, electricity supply, site mix, allocation method, product specification, or representative period.

11. Data Sources

Source id	Type	Reference	Used for
unsd-cpc-3-2025	official_guidance	United Nations Statistics Division, Central Product Classification Version 3.0, explanatory notes dated 30 June 2025, subclass 27993, https://unstats.un.org/unsd/classifications/Econ/Download/In%20Text/CPC_Ver_3.0_Exp_Notes_30Jun2025.pdf (retrieved 2026-08-13).	Exact CPC subclass identity and separation from adjacent textile articles.
ec-pef-2021-2279	official_guidance	European Commission Recommendation (EU) 2021/2279 on the use of the Environmental Footprint methods, https://eur-lex.europa.eu/eli/reco/2021/2279/oj (retrieved 2026-08-13).	Life-cycle inventory completeness, company-specific foreground data, physical allocation preference, normalization, and quality disclosure.
jrc-textiles-bref-2023	official_guidance	European Commission Joint Research Centre, Best Available Techniques Reference Document for the Textiles Industry, 2023, https://eippcb.jrc.ec.europa.eu/reference/textiles-industry (retrieved 2026-08-13).	Textile-operation process coverage and conditional recording of energy, water, chemicals, wastes, wastewater, and emissions.
repon-mikucioniene-2021	literature	Repon, M. R.; Mikucioniene, D. Progress in Flexible Electronic Textile for Heating Application: A Critical Review. Materials 14 (2021) 6540. https://doi.org/10.3390/ma14216540. Open full text verified through Europe PMC PMC8585370.	Metal-wire/base-yarn combination; metal-coated yarn route; sputtering, electroless plating, and vapour-deposition route evidence; route and composition disclosure.