Gall Oaks and FG bags….Google search?

Galls are rich in tannins, commonly used in the leather-industry
Galls on a Portuguese or Gall Oak

On our site you may have come across the words ‘naturally-tanned’. What does that actually mean? Before a leather hide gets to the  flexible and beautiful state it is in when Fernando buys it, it has gone through a whole number of processes. One of these is the process of tanning. Tanning permanently changes protein structure, converting an animal skin into leather. An animal skin can be worked and not tanned, producing Rawhide, which is paler than leather and more susceptible to water damage.  The tanning process is carried out either naturally or chemically; naturally using tannins, and chemically using various products but most commonly, chrome. (Chrome tanning is a faster process than natural tanning and tends to produce leathers that are slightly more stretchable.) Tannins occur naturally in the barks and leaves of many trees… chestnut, oak, tanoak, wattle, mangrove… and also in galls. This leads us to our title! The galls (the balls formed by the Gall Wasp, also known as ‘Oak Apples’…) of the Gall Oak, or Portuguese Oak (Quercus faginea) are particularly high in tannins. These beautiful trees grow in our area (Natural Park ‘Sierra de Grazalema) where they are known as ‘Quejigos’ and are usually quite full of galls. The story is that these galls used to be harvested and transported by mule down to Fez, to be used in the tanning industry there! You may wonder why go to so much trouble, weren´t there Gall Oaks in Morocco?  The answer appears to be that in the Gall Oaks in that area are a different subspecies (ssp.broteroi) and I´m assuming that the galls are not of the same quality? (any further information gratefully received!).
What you may want to know is… exactly which natural tannins are used to make the leather used for Fernando´s bags? Well… ‘Watch this space…!’