Yeah, I do wash the linen trousers from time to time. Not after every even though, as that would be silly. But once or twice a year.
They are over trousers anyway, they are not official regulation issue for the time we portray. I.e. they are used to protect the real woolen breeches.
This is also the reason why they are so wide cut, they are supposed to fit another pair of trousers and gaiters underneath.
For the timeframe the 85e is potraying, their trousers are completely wrong though. For a Bardin Regulation impression 1813/14-15 you should either have long woolen trousers made out of tricot wool, or long linen trousers.
Their trousers are made from cotton and are high bleached.
Also cleaning your trousers would not have happened on campaign. They would have cleaned it from time to time, but really, people had better stuff to do than to care for their trousers.
Yes, on Garrison your trousers were expected to be clean, so was everything else. You were even expected to keep all your issued stuff (Can you imagine??) Anything that was missing had to be purchased back from your own money.
On campaign this is completely different. There are dozens of reports of soldiers throwing away half of their issued gear and instead opting for their own. They simply had no use for it. Officers during campaign usually did not care much about it, they completely accepted it. This goes even as far as regimental commanders supplying whole batches of shako-covers, catridgebox-covers, canteen-covers and overtrousers to the entire regiment.
The reason why Bardin opted for long trousers and shorter gaiters in 1812 was mainly due to the fact that he and everyone else knew that ordering breeches and long gaiters was a waste of money. People would just throw them away.
And linen trousers can look white when they are new, depending on what type of linen was used. Caspers new trousers for example are very grey, and will never look very close to a bright white. My trousers for example are fairly different.
Look at this photo from the first event I wore my new linen trousers:
They look pretty white, right? Still, this is nothing compared to those white cotton trousers everyone is wearing.
Oh btw. the grenadier on the left is wearing those long wool trousers that I was talking about earlier.