[QUOTE 4952748, member: 9609"]what does the rain do to it ?
its going to have to get used with wet, I live in Scotland
[/QUOTE]
It is a long story but I'll try my best.
There are two broad types of tanning used to turn animal skins into leather. There's so-called vegetable tanning that uses chemicals derived from the bark of some trees such as acacia and I believe oak. It is also called organic tanning by anyone who wants to spruce up the method for marketing purposes.
Then there is chrome tanning. Chrome salts are used to tan the leather and this is a chemical process using blue chrome salts.
The results from the two tanning processes are different. If it is veg-tanned, then the leather is reasonably stiff but becomes very soft and moldable when when. When it dries, it keeps its new shape. Veg-tan leather also has a memory. If you fold it several times, it will soften on the fold and keep the fold. Chrome-tanned leather is permanently soft and cannot soften more when soaked. It is so soft that it is used for furniture, clothing, shoes, handbags etc. Veg tan leather is used by artisans who make stiff leather good from it such as suitcases, stiff handbags etc.
Chrome tan leather can be washed and don't seem to suffer from it. It will also not readily stain. Veg tan leather on the other hand, stains when wet, changes colour, becomes soft, takes on new shapes etc.
Brooks saddles are made from veg tan leather. Reason being is that the leather is structural and chrome tan leather will just flop about. However, when it gets wet whilst you are riding it, it changes shape dramatically. First it starts to stretch and sag in the middle but eventually it takes on the shape of a wedge. It even has a name - arse hatchet and is as uncomfortable as it sounds. The big trick is to try and keep it dry and therefore disciples of Brooks will concoct, mix, blend, invent, buy and steal all sorts of waxy substances to "feed" *(bullshit word, leather can't eat) the leather. What they are really doing is attempting to prevent it from absorbing water by blocking the leather's capillaries with wax. It works to an extent. The underside is particularly vulnerable and the best prevention from spray wetting is mudguards.
Other saddles with plastic shells, can also be covered with leather and there are plenty of examples around. These are covered in chrome leather. Getting wet is no big deal and it will never change shape because the plastic shell doesn't budge from any beehind.