British Museum leather dressing

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British Museum Leather Dressing has been used by many conservators since its publication. ^[1][2]

Use

Leather dressings are applied as lubricants to leather, particularly items that are in use, rather than on static display. They are beneficial when a leather item has lost its flexibility, or when it must be protected from future variations in humidity.

Lubricants should be avoided for leather unless necessary. An excess of them may attract airborne dust or even moulds. If the item does not need to be flexible, then there is rarely a need to lubricate it. An excess of lubricant may actually act to seal the surface and repel moisture, causing the leather to dry out even further. There is certainly no need to 'feed' leather — it's already dead. If the requirement is to improve the surface appearance alone, a wax treatment such as Renaissance Wax may be more appropriate. Most lubricants will darken the leather.

Formulation

The basic formulation is:

200 g	anhydrous lanolin
30 ml	cedar oil (acts as a fungicide)
15 g	beeswax (optional)
330 ml	X-4 solvent or hexane (solvent)

The first three ingredients are mixed warm, then added to the cold solvent. Allow to cool while constantly stirring. ^[3] Exercise care, as hexane is highly flammable.

Variations

There are several variations in the formulation.

Sometimes 60% of the lanolin was replaced by neatsfoot oil.

One disadvantage of the solvent hexane is its tendency to evaporate rapidly. Before the fat/hexane mixture has been able to penetrate deep into the leather the hexane evaporates to the surface of the leather, taking most fat with it.

While beeswax prevents air pollutants from penetrating the leather it does this by closing off the leather, thus disturbing the water balance and causing the leather to dry out. ^[4]

In Use

The British Museum Leather Dressing was part of an elaborate leather conservation programme. Other steps entailed cleaning the leather, if necessary with soap and water, and applying an aqueous solution of 7% potassium lactate as buffer. A warning was given about the dangers of using too much lactate which made books sticky and could cause fungal growth. The books had to be absolutely dry when the leather dressing was applied .

Apply sparingly to the leather and rub well. Wait two days, then polish the treated leather with a soft cloth. Very hard leather can be soaked in a solution of one part British Museum Leather Dressing: three parts Stoddard solvent. ^[5]

British Museum Leather Dressing darkens the leather, but it is a treatment with a good success record.

References

1. ^ (Plenderleith, 1946)
2. ^ Plenderleith, H.; A. Werner (1971). The conservation of antiquities and works of art, 2nd ed., London: Oxford University Press. 
3. ^ Caring for Cultural Material - Leather. reCollections - Heritage Collections Council of Australia. Retrieved on 2007-04-27.
4. ^ Concise survey of conservation treatments. Koninklijke Bibliotheek - National library of the Netherlands. Retrieved on 2007-04-27.
5. ^ Leather Conservation. Conservation Research Laboratory, Texas A&M University.. Retrieved on 2007-04-27.