I know they do it but I don't know why

i am sorry do you mean the yellowing or the greying over time.
the yellowing is a chemical reaction and is a problem every white leather faces over time

the greying is mostly evident with clemence (if i think of the same thing like you) as microdust setlles in between the bumps and therefore leads to a duller greyer appereance. but that can normally be cleaned

Ooooo ..... I learn something new today! Thank you, lilach. With you, HG, Grands Fonds, hello, DQ, orchids (sorry if I missed anyone) ... this H sub-forum becomes a power house!
 
^^GF was just telling me that Hermes has found a way to get around this now, the greying I mean.
OOOH this is musique to my ears!!! :smile::tup: i was told to send it in every year after summer so it goes to paris for cleaning and that would keep it white as long as possible but that they all go yellowish in the end...not sure on the yellowish, hope it does not happen automatically.
 
yup. the reason is as a lot of customers love to hang the lock onto the turnkey all the time which can lead to the famous smiley. while usually is not a huge problem with textured or normal leathers (as long as the lock is not overdipped in gold which happens ins 0,001%)it can do possible damage to exotic skins.
they started to add the cover to the white leather only a couple of years ago as the smiley could also become more evident on white leather as the metals could react with the dye (had something to do with the way they dye paint bleach )the leather for the solid white appereance

Ohh, I'm SO glad you're back!!!