Where Did My Leather Dining Chairs Come From?
They say you can't make a silk purse from a sow’s ear. While this may be true, other animal parts can be used to make luxury goods, specifically leather made goods. Top quality full grain leather dining chairs are covered with a pelt that typically come from cattle and after treatment result in a material that is resistant to flame and water, stretching and shrinking as well as being pliable and tough. But before the skins or hides can be used they must undergo a lengthy preparation process. This is called tanning, a word that comes from the now little-used process that used tree bark containing tannin to cure the hides. Today the most common form of tanning is called chrome tanned leather. Here is a brief outline of the process.
When the hides are delivered to the tannery, they have generally been coated with salt or other chemicals that retard purification. The hides are placed in drums containing water, which revolve slowly, washing away the added chemicals. After about five hours the water is drained away and replaced with a mixture of water, lime and sodium sulphide which is agitated periodically for half a day. This removes hair and unwanted proteins. The hides are then processed to remove fat from the inner surface and split to the desired thickness.
Following this, the hides then have to get the lime and sodium sulphide removed, which involves several other periods of rinsing and the addition of other chemicals that help prepare the hide for the next step. This is where the main tanning agents are introduced, chrome tanning salt, in which the hides will be immersed for several hours before magnesium oxide is added and the drum left to run overnight. After draining the leather is put through giant rollers to remove moisture before being brought back to a neutral pH. It than gets synthetic or natural tannins added to give the required finish before being dyed to the desired colour along with the addition of oils to prevent damage to the natural fibres when the leather is dried out.
There are a multitude of methods used for drying the leather, but for full grain leather the hides are normally stretched in the characteristic shape of the real leather logo, they then pass through a drying tunnel. After being sprayed with water on the flesh side, the hides are left for several hours to stabilise, and in the case of full grain leather, are now ready for the final preparation. By this stage the skins have been sorted and earmarked for the various buyers. It is then time to give the final finish. This will depend on the requirements of the buyer, but there will be pigments, binders and lacquers added to give a consistent finish to the batch that ends up covering your leather dining chairs.