It is difficult to get 100% cotton socks that are made of organic fibres and manufactured without recourse to exploiting desperate people in the so called third tier countries, most of which may be in the Far East.
I have just been sent a pair of socks from BlueBuck. The label, was attached with cotton thread, rather than the little bits of plastic, and shows details of the main points.
With 9% nylon (polyamide) and 1% Elastane the socks can not be composted without having to remove the stringy remains of 'plastics'. This also means that factories have to make this stuff from arguably questionable resources, using workers that may well be hidden from the view of the Fair Trade flossies.
This is a problem in many brands and I would like to find socks made of fibre other than cotton, linen, hemp or nettle. Apparently nettle fibre was used in the UK during the second world war.
The Bluebuck socks are sized (L/XL) and measure 24cm from <extreme heal to toe> and are fairly thick.