Number
437-EN
Section
General Section
Use
Sector
Other
Function
Plating agent
Process
Treatment of articles by dipping and pouring
Product category
Metal surface treatment products
Application
Production of decorative surfaces with functional properties
Abstract
Chromium trioxide was placed on the REACH Authorisation List in 2013 and its use has needed a specific authorisation in the EU since 2017. Instead of applying for an authorisation to further use the toxic substance in the electroplating of metal sanitary appliances it was decided to implement a trivalent chromium process and to eliminate chromium trioxide completely. In parallel, the nickel sublayer will be substituted by a white bronze.
Substituted substances
Chromium trioxide
CAS No. 1333-82-0 EC No. 215-607-8 Index No. 024-001-00-0
Chemical group
Chromium compounds; metal oxides
Classification: hazard statements
H271 May cause fire or explosion; strong oxidiser
H350 May cause cancer
H340 May cause genetic defects
H361f Suspected of damaging fertility
H330 Fatal if inhaled
H311 Toxic in contact with skin
H301 Toxic if swallowed
H372 Causes damage to organs through prolonged or repeated exposure
H314 Causes severe skin burns and eye damage
H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled
H317 May cause an allergic skin reaction
H400 Very toxic to aquatic life
H410 Very toxic to aquatic life with long lasting effects
Other adverse effects
The substance is: 1 carcinogen (IARC: chromium VI compounds), as listed in the Substance Database according to SUBSPORT Screening Criteria (SDSC).
Nickel sulphate
CAS No. 7786-81-4 EC No. 232-104-9 Index No. 028-009-00-5
Chemical group
Metal
Classification: hazard statements
H350i May cause cancer by inhalation
H341 Suspected of causing genetic defects
H360D May damage the unborn child
H332 Harmful if inhaled
H302 Harmful if swallowed
H372 Causes damage to organs through prolonged or repeated exposure
H315 Causes skin irritation
H334 May cause allergy or asthma symptoms or breathing difficulties if inhaled
H317 May cause an allergic skin reaction
H400 Very toxic to aquatic life
H410 Very toxic to aquatic life with long lasting effects
Other adverse effects
The substance is listed in the SDSC database: CLP Regulation: sensitiser (H317, H334).
Alternative Substances
Boric acid
CAS No. 10043-35-3 EC No. 233-139-2 Index No. 005-007-00-2
Chemical group
Boron compounds; inorganic acids
Classification: hazard statements
H360FD May damage fertility. May damage the unborn child
Other adverse effects
The substance is: endocrine disruptor cat. 1 (EU EDC database), as listed in the Substance Database according to SUBSPORT Screening Criteria (SDSC).
Chromium sulfate
CAS No. 10101-53-8 EC No. 233-253-2 Index No.
Chemical group
Dicopper oxide
CAS No. 1317-39-1 EC No. 215-270-7 Index No. 029-002-00-X
Chemical group
Metal
Classification: hazard statements
H332 Harmful if inhaled
H302 Harmful if swallowed
H318 Causes serious eye damage
H400 Very toxic to aquatic life
H410 Very toxic to aquatic life with long lasting effects
Tin methane sulfonic acid
CAS No. 53408-94-9 EC No. 610-996-4 Index No.
Chemical group
Classification: hazard statements
H302 Harmful if swallowed
H314 Causes severe skin burns and eye damage
H317 May cause an allergic skin reaction
H411 Toxic to aquatic life with long lasting effects
Other adverse effects
The substance is listed in the SDSC database: CLP Regulation: sensitiser (H317, H334).
Reliability of information
Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication
Reason substitution
CMR
other toxic effects
ecotoxicity
physical hazards
Hazard Assessment
a) Human health:
Two substances of very high concern (Chromium trioxide and Nickel sulphate) are substituted with substances of lower toxicity. The established white bronze process is free of cyanide. A third substance of very high concern (Boric acid, Repr. 1B, H360FD) remains in the process, which is under regulatory evalution but has not been placed on the authorisation or restriction list at the time point when the case study was described. It is assumed that the overall risks for human health are reduced in comparison to the conventional procedure by avoiding the use of chromium trioxide and nickel sulphate.
b) Environment:
e.g. waste reduced/increased Nickel leaching from finished products is completely barred as Nickel is substituted. This is an important aspect as nickel leaching from sanitary armatures is considered to be a serious problem.
Description of Substitution
a) Motivation why to apply the alternative:
The authorisation applicable to the company expires in 2024. The high costs of reviewing the authorisation have provided the impetus to take the initiative. There are several alternative chromium III processes, but not with the required properties. In particular, it is not possible to do without nickel in all of these processes. Therefore, the chromium III process was optimised in close cooperation with a supplier.
Leaching of nickel from finished products is completely eliminated as nickel is replaced. This is an important aspect as nickel leaching from sanitary fittings is considered a serious problem.
b) Description of procedure or technology (including pre-/post-processing):
Chrome coating of brass is an electrochemical process. Parts are cleaned and degreased in several baths. A white bronze coat is deposited as substitute for the Nickel sub-coating. Chromium is electrolytically deposited on the sub-coat. Coated parts are passivated electrochemically and finally rinsed. The overall process is fully automated.
c) Way of application:
e.g. spraying, dipping, open/closed system etc. Parts are manually attached to racks. Racks are moved by a suspension crane into the galvanising plant where they are automatically transported along the bath line and dipped sequentially into the respective baths.
d) Risk management measures (technical, organizational and personal):
Access to the galvanising plant and to the baths is restricted to maintenance purposes only for specialised staff. Exhaust systems are installed at the upper edges of the baths. During maintenance and control personal protection equipment (protective coverall) is worn.
Advantage or Disadvantage of alternative
Aspect |
Advantage/disadvantage to conventional process |
---|---|
Technical requirements |
Corrosion resistance: as defined by EN 248 met by 90% |
Implementation |
Main obstacles: Larger required space (in implementation phase both processes are run in parallel) |
Operational expenses |
Labour costs: + 5% (bath maintenance) |
Other |
The DVGW (German Association of the Gas and Water Industry) certificate of conformity has been available since 03/2022. The galvanized products comply with the limit value requirements from the Drinking Water Directive (TrinkwV 2001). |
Supporting information:
Costs for ESH, OSH and waste disposal are potentially lower, but as the protection level will be upheld there is no change.
General economic aspects:
Service life of products is comparable to Cr(VI) coated products. Availability of materials is comparable to the Cr(VI)/Ni based process. The main advantage results from the combined transition from Cr(VI)/Ni to Cr(III)/CuSn and thus removal of Nickel from the end product. Bath temperature is lower for white bronze coating (30°C instead of 60°C) than for Nickel, and current is lower (~1 A instead of 4–6 A). Process speed improves remarkably as the manual activity of parts plugging can be dispensed with, which is necessary in the Cr(VI)/Ni-based process, in order to prevent nickel contaminations.
Case/substitution evaluation
The case story shows the substitution of two carcinogenic and sensitizing substances, chromium trioxide (Carc. 1A, H350; Skin Sens. 1, H317) and nickel sulphate (Carc. 1A, H350i; Skin Sens. 1, H317; Resp. Sens. 1, H334), in decorative chrome plating with a functional character. Instead of hexavalent chromium, trivalent chromium is used in the plating process; the final nickel layer is replaced by white brass.
Boric acid (Repr. 1B, H360FD) remains as SVHC in the presented alternative process. It is also used in the conventional plating process. The risks for man and environment are still under regulatory evaluation and remain unclear at the time of compiling the case story. Should information and evidence regarding this alternative or a safer and more sustainable alternative be present, please contact SUBSPORTplus.
In Germany, there are limit values for various metals, such as chromium, nickel and copper, according to the Drinking Water Ordinance. The limit values (e.g. for copper of 2 mg/l) can be complied with by the alternative.
Release of nickel compounds into the drinking water is known to occur from conventional plated products (see further information), if the products are not plugged before coating. However, plugging is time and cost intensive (personal communication). Substitution of the nickel sublayer is an alternative to increase drinking water safety and avoids the use of nickel sulphate in the first place.
For occupational safety and health: Substitution of two carcinogenic substances at the workplace is regarded as added value. If available, occupational exposure limits for the alternative substances used must be complied with as well. Adequate protection measures need to be taken into account at the workplace after a proper risk assessment.
State of implementation
Pilot study
Enterprise using the alternative
Heinrich Schulte GmbH & Co. KG Grünlandweg 11 58640 Iserlohn Tel.: 02371 - 90 90 0 Fax: 02371 - 90 90 99 https://www.heinrichschulte.com">https://www.heinrichschulte.com">https://www.heinrichschulte.com
Availability of Alternative
pilot study The nickel leaching test according to DIN EN 16058 (26-week test) was passed.
Type of information supplier
Producer / distributor
Contact
La Tecnogalvano S.R.L. Via Salvo D'Acquisto, 9/b 28076 Berzonno di Pogno (NO) Italy https://latecnogalvano.it/en/galvanic-processes.html#innovativi
Further information
The factsheet describing the case study is available as a pdf download: to factsheet 437-EN
Publication source: author, company, institute, year
company
Date, reviewed
June 25, 2023