CUSTOMERS EXTRANET
STARLIMS LABORATORIES
- ABOUT CTC
- EXPERTISE AND SERVICES
- Raw hide - Tannery
- Footwear
- Leather goods - Glove-making
- PPE
- Environment
- CSR
- Training
- BLOG AND NEWS
- CTC VIDEOS
- LEAFLETS AND PUBLICATIONS
- CUSTOMERS EXTRANET
EN
Tanning is the chemical process by which putrescible hides and skins are transformed into rot-proof leather. It makes the skin resistant to decomposition, while retaining desirable qualities such as suppleness and durability.
Traditionally, metals such as aluminium, zirconium, iron, titanium and especially chromium have been used in mineral tanning. Basic chromium(III) sulphate is particularly widely used, accounting for around 85% of leather sold.
However, chromium(III) can, in certain cases, oxidise to chromium(VI), an allergenic substance whose concentration in leather is restricted to 3 mg/kg (entry 47 of Annex XVII of the European REACH Regulation).
The “metal-free leather” certificate is issued when the total content of the five tanning metals (aluminium, chromium, iron, titanium, zirconium) is less than 1,000 mg/kg, in accordance with standard NF EN 15987:2015.
Contact our team for detailed information on the procedure to follow:
These certificates can help you reinforce the trustworthiness of your products and meet the growing demand for transparency.
This is chromium in its trivalent form. Leather produced in this way (85% of all leather sold) contains between 20,000 and 30,000 mg/kg of trivalent chromium (chromium(III)).
The use of chromium(III) has not been questioned by the European authorities. However, in leather, some of this chromium(III) can sometimes oxidise to chromium(VI) (hexavalent chromium), an allergenic substance that is known to cause skin reactions and whose concentration is limited to 3 mg/kg in leather in contact with the skin (entry 47 of Annex XVII of the European REACH Regulation).
As part of the proposed REACH restrictions on skin-sensitising substances, the European Chemicals Agency (ECHA) committees are proposing to reduce this permissible limit for chromium(VI) to 1 mg/kg in leather within 5 years 2027. No date has been set by the EU for the signing of this text.
The other solutions used to tan hides and skins into leather are synthetic organic tanning agents (syntans) and vegetable tannins. Vegetable tannins give leather fabulous properties, but these are nothing like those of chrome-tanned leather (suppleness, colour, temperature resistance, etc.). The other metal-free tanning agents currently on the market are no better at meeting all consumer expectations.
Metal-free tanning itself has been weakened by the inclusion of glutaraldehyde in the list of candidate substances for REACH Annex XIV, and by the ongoing public consultation aimed at including it in the next ECHA recommendation listing the substances to be prioritised for inclusion in REACH Annex XIV.
The European Commission looks to the recommendations of the ECHA to update Annex XIV. The inclusion of glutaraldehyde in this annex would prohibit its use in European tanneries, and encourage imports into the EU of leather tanned with this substance by non-European manufacturers.