British Museum

British Museum

The British Museum is a museum of human history and culture in London. Its collections, which number more than seven million objects, are amongst the largest and most comprehensive in the world and originate from all continents, illustrating and documenting the story of human culture from its...

 Leather Dressing has been used by many conservators since its publication to protect and conserve leather.

Use

Leather dressings are applied as lubricant

Lubricant

A lubricant is a substance introduced to reduce friction between moving surfaces. It may also have the function of transporting foreign particles and of distributing heat...

s to leather

Leather

Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...

, 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 is already dead. If the requirement is to improve the surface appearance alone, a wax treatment such as Renaissance Wax

Renaissance Wax

Renaissance Wax is a brand of microcrystalline wax polish that is widely encountered in antique restoration and museum curation. Although not appropriate for all materials, it is known to and used by almost every collection. It is also used as a primary finish for cabinetry and furniture....

 may be more appropriate. Most lubricants will darken the leather.

Formulation

The basic formulation is:

200 g	anhydrous lanolin Lanolin Lanolin , also called Adeps Lanae, wool wax or wool grease, is a yellow waxy substance secreted by the sebaceous glands of wool-bearing animals. Most lanolin used by humans comes from domestic sheep...
30 ml	cedar oil Cedar oil Cedar oil, also known as cedarwood oil, is an essential oil derived from the foliage, and sometimes the wood and roots, of various types of conifers, most in the pine or cypress botanical families...  (acts as a fungicide)
15 g	beeswax Beeswax Beeswax is a natural wax produced in the bee hive of honey bees of the genus Apis. It is mainly esters of fatty acids and various long chain alcohols...  (optional)
330 ml	X-4 solvent or hexane Hexane Hexane is a hydrocarbon with the chemical formula C6H14; that is, an alkane with six carbon atoms.The term may refer to any of four other structural isomers with that formula, or to a mixture of them. In the IUPAC nomenclature, however, hexane is the unbranched isomer ; the other four structures...  (solvent)

The first three ingredients are mixed warm, then added to the cold solvent and allowed to cool while constantly stirring. Care should be exercised, as hexane is highly flammable.

Variations

There are several variations in the formulation.

Sometimes 60% of the lanolin was replaced by neatsfoot oil

Neatsfoot oil

Neatsfoot oil is a yellow oil rendered and purified from the shin bones and feet of cattle. "Neat" in the oil's name comes from an old name for cattle. Today, many consider the best quality neatsfoot oil to be that which comes from the legs of calves, with no other oils added. Neatsfoot oil is...

.

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.

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.

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