An Improved Understanding in the Conservation of Leather Bookbindings

Karen Vidler pursues ongoing research and training into the conservation of leather bookbindings.  She has attended academic training in leather chemistry & technology as well as the hands-on manufacture of leather. She applies current research in improved examination and treatment of bookbinding leather into her practical and teaching work. Her areas of particular interest are acid decay (red rot), age hardening and fire damage in bookbinding leathers manufactured from the middle ages through to modern tanned and finished leather. As well as developing improved techniques for repairing leather bindings without the need for complete removal of the original leather.

The Use of Leather Dressings - extract from ARCmagazine article

Leather dressings can be purchased as a liquid or cream usually containing a mixture of fats, oils and waxes in a solvent. Throughout the 20^th century leather dressing has been used for improving the look and ‘condition’ of vegetable tanned leather when it appeared to be dry and losing flexibility. They are part of a group of substances known as surface coatings which are used in the conservation and restoration of leathers. This use of leather dressing comes from the belief that an application could replace the loss of the lubricant worked between the leather fibres during manufacture to give the leather the desired physical properties required for use as bookbinding leather.

• Visual examination is a limited way to determine the condition of any vegetable tanned leather. The ‘dry’ appearance could be due to factors such as the loss of the bound water in the fibres structure, conversion of the fats ‘stuffed’ into the leather during manufacture or from a recent application of dressing or another chemical change in the leather^1,. An accurate assessment of the leather must be determined to ensure the leather dressing will not in fact accelerate degradation².
• There is well researched, published evidence on the long-term degradation caused by the use of leather dressing^3,4. Pushing more fats and oils into the leather fibre structure will fill voids in the upper layer of the leather and replace sites of bound water - both of which are needed for the leather fibres to slide over each other during flexing. Leather dressing will make the leather less flexible and cause hardening and  eventually cracking and discolouration over time.

In summary:

• New leather does not require leather dressing unless you are seeking to enhance the grain and gloss of the leather for a short time
  
• Old leather does not require leather dressing and is in fact harmful in the short and long term to the appearance, physical properties and chemical stability within the leathers fibres structure.