WATCH OUT! There are many different models in the Sealskinz socks range. SEE HERE If you are the sort of person who feels overwhelmed by the choice of Inov8 shoes, you will suffer here. It really is best to buy from a shop where you can try the socks on, as the sizes vary between models, and also have changed since I last bought them. Do not assume, as I did, that what fitted you in the past will still do so - you will just have to send them back. AND in large outlets like Nevisport and Cotswold, the last time I looked, they were only offering 2 newer models which are closer fitting than the old and which even in the largest sizes are not big enough for me to wear over thin liners (in size 9 - 9.5 Inov8s). I was despairing until I visited Out & About in Harrogate and they explained the situation and came up with the older model Sealskinz Mid Light socks. Even then I needed the XL size, so I don't know what large chaps with seriously big feet can do.
I find Sealskinz socks a godsend. Carole Engel (who co-organises the Hebden and has a hand in the apple crumble) explained to me how to get the best out of them. DO NOT WASH THEM UNLESS ABSOLUTELY NECESSARY. I regard them as another form of shoes (they cost about the same). I never wash my shoes and I rarely wash my Sealskinz. I protect them on the inside with thin liner socks (Coolmax in summer, polypropylene in winter) and on the outside with Shorty Event gaiters (which also help prevent their being swamped when wading through streams). If I had to, I would wash them by hand in cold water only (no detergent or soap) and drip dry.
A, your washing advice is spot on and what I now do; having ruined my first pair by machine washing and drying on a radiator!!