Number
442-EN
Section
General Section
Use
Sector
Other
Function
Flux agent
Oxidizing agent
Process
Treatment of articles by dipping and pouring
Manual activities involving hand contact
Product category
Metal surface treatment products
Welding and soldering products, flux products
Application
Use in jewellery workshop: boric acid and disodium tetraborate (Borax) as soldering flux to protect metal from oxidising during soldering; silver processing mixture containing sodium selenite used to tarnish silver to form a black silver sulphide layer for decorative purposes
Abstract
A jeweller operating a personal workshop implemented a chemical substitution to improve occupational safety at work. After checking the hazard information of all used chemicals, two mixtures were prioritised for substitution: i) soldering flux containing boric acid (CAS: 10043-35-3; EC: 233-139-2) and disodium tetraborate/Borax (CAS: 1303-96-4; EC: 215-540-4). Both are included in the candidate list; and ii) silver processing (tarnishing) mixture containing sodium selenite (CAS: 10102-18-8; EC: 233-267-9). The use of hazardous chemicals in a jeweller?s workshop is a little addressed issue, especially in small sized companies and personal workshops. But personal exposure issues can be a driver to switch to environmentally and health-friendly chemicals and processes.
Reliability of information
Evidence of implementation: there is evidence that the solution was implemented and in use at time of publication
Reason substitution
CMR
skin/respiratory sensitizing
other toxic effects
Hazard Assessment
Substances to be substituted:
Boric acid and Borax are both SVHC substances on the REACH candidate list for their reproduction toxic property and harmonised classification as Repr. 1B, H350FD. According to the SUBSPORTplus screening list criteria, boric acid is listed as endocrine disrupting substance category 1.
Sodium selenite has a harmonised classification for acute toxic, aquatic chronic and skin sensitising properties: Acute Tox.2 (H300), Acute Tox3 (H331), Skin Sens.1 (H317), Aquatic Chronic 2 (H411).
Alternative substances:
Orthophosphoric acid has skin corrosion properties with harmonised classification for Skin Corr.1B (H314). The other alternative substances have no harmonised classification according to Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation). Neither is there an entry in the SUBSPORTplus database. Self-classification of the substance provider in the SDS indicates acute toxic, skin irritant, eye irritant and STOT SE 3 properties.
Description of Substitution
a) Motivation to apply the alternative:
Alternative for soldering flux: our main motivation was to increase occupational safety and reduce exposure to reprotoxic substances. In addition, we wanted to avoid the use of SVHC substances.
Alternative for silver processing mixture: our main motivation was to increase occupational safety and reduce the exposure to sensitisers and acutely toxic substances.
b) Description of procedure or technology (including pre-/post-processing):
Alternative soldering flux containing orthophosphoric acid (2% conc. in mixture): the default application is spraying, but it can be applied by dipping also. Soldering flux is typically applied before the jewellery pieces are soldered together or heated and washed off with water afterwards.
Alternative for silver processing mixture (containing potassium thiosulphate hydrated (15-35%) and dipotassium trisulphide (5-10%): Longer application time during the manufacturing or hot application that was not needed previously. Need for tarnisher solution preparation (additional work). Best way of application is dipping only, as opposed to different styles of application previously (e.g. ap-plication with a brush on small areas was possible with previous product).
c) Way of application: e.g. spraying, dipping, open/closed system etc.
Alternative for soldering flux: spraying or other modes of application (e.g. dip-ping).
Alternative for silver processing mixture: Dipping only.
d) Risk management measures (technical, organizational and personal)
Alternative soldering flux: protective gloves, googles and protective clothing is recommended. Significantly decreased PPE needs.
Alternative silver processing mixture: protective gloves, googles are recommended. Significantly decreased PPE needs.
e) Advantage/disadvantage to conventional process
Technical requirements are similar for the alternative for soldering flux. The application mode for the alternative for the silver processing mixture is different.
Operational expenses for the alternative for soldering flux: Price increase nearly tenfold. But there are low use amounts, thus there is no economical significant increase overall.
Alternative for silver processing mixture: Price increase two- to threefold.
Case/substitution evaluation
Reprotoxic substances can be replaced. The chemical alternatives were assessed against hazards in hazardous Substance Database according to SUBSPORTplus Screening Criteria (SDSC) and passed.
Workplace safety has to address corrosive properties mainly. Mixture substitution reduces waste and risks to aquatic environment.
State of implementation
Full capacity
Enterprise using the alternative
Company: Varva, MB. Facebook page link (https://www.facebook.com/varvajewellery/?__tn__=%2Cd%2CP-R&eid=ARDViJXvTFWwAXfN-l1tvgPxI7OHzzyXKhwtx35Vv9z7WkYBk5eCSlVdiWGpE7IJeBWOQINhDHotdJBf); e-mail address: varva.jewellery@gmail.com; Phone: +370 627 95226
Availability of Alternative
The alternatives are available on the market.
Type of information supplier
User
Contact
soldering flux: Firescoff Ceramic Flux; silver processing (tarnishing) mixture: Liver of sulfur extended life gel (XL gel)
Further information
Alternative for soldering flux: Original SDS (link: https://royal-stone.pl/product/attachment/12046/4243e98c6537b5222600650d06e3afe3); Alternative SDS (link: https://www.hswalsh.com/sites/default/files/related_files/TF28
Firescoff.pdf/ link: https://contenti.com/media/catalog/pdf/msds/510-812_etc.pdf)
Alternative for silver processing mixture: Original SDS: attached; Alternative SDS (link: http://www.metalclay.co.uk/content/SDS/XLGel-Liver_of_Sulfur_Extended_Life_Gel_%28XL_Gel%29_%281%29_%28US%29_EN_sds.pdf)
Date, reviewed
March 1, 2013