What is Steam Cleaning Leather & Why Is It Bad For Leather?
What is Steam Cleaning Leather & Why Is It Bad For Leather?
Using wet heat on leather is bad for the surface coating, it can cause moisture to get below the clear lacquer coating causing separation to take place, in time this will cause the clear coat to lift away and all that’s left is the binder paints below. These can then break down and become unstable and this is when wear starts to happen.
Wet heat will also penetrate the leathers fibre structure as modern leather has around a 1% breathability factor, once these fibres become in contact with wet heat the molecule structure is changed, and this can cause leather to harden and become weak.
How Leather Is Painted and A Top Coat Applied
Leather is made by chemically cross-linking the protein collagen in hides & skins.
This is done in many different ways, using different chemistry and a different approach.
The results from the different tanning systems improve the hydrothermal stability of the tanned collagen matrix so that it will not denature / deteriorate at elevated temperatures and will stand a cycle of drying, re-wetting, drying with no significant bad results.
The degree of hydrothermal stability is determined by the type of tanning system and how strong the bonds are chemically between the tanning agent and the protein molecules of the collagen. At the low end of stability you get vegetable tanned and oil tanned leather and at the upper end you get the mineral tans such as chrome, aluminium and zirconium.
Each tanning agent imparts a significant amount of the final character to the leather (flexibility / firmness, density, hardness etc). Chrome tanned leather in the tannery will stand a boiling test without shrinkage – this is one of the production measures used to verify the process is complete. Why in footwear? Chrome is still the preferred leather to remain flexible after all of the heat treatments that occur during shoe making.
Other mineral tans will not produce as high as a performance as chrome.
With very heavily finished leather (effectively fully pigmented – plastic coated if you like) it may be possible to get away with a surface steaming, but there’s no guarantees with that since you don’t actually know what’s underneath and you don’t know it’s chemical constituents… If you take the approach that wet heat is potentially damaging.
John from Avery Leather is has over 40 years experience in all aspects of leather and tanneries. John trained at the British School Of Leather Technology, Adopted as “Fellow of the Society of Leather Technologists & Chemists” (FSLTC) in November 2001 and SLTC President, 2006 – 2008.