A waterproof construction is a different system
The Sealskinz Runton sock has an outer fabric, Aquasealz membrane and merino-containing inner. That is a three-layer product, not an ordinary wool sock made waterproof by its fiber content.
Check entry points and footwear space
Read the maker’s cuff and Hydrostop instructions for the exact variant. Check the complete sock in your footwear and consider how water could enter above its cuff. This guide does not certify a complete waterproof footwear system.
Keep market and variant questions visible
The source-proof Runton page establishes the named construction, but its exact US purchasing variant remains unresolved here. Do not replace it with a similarly named Briston, another weather version or an unverified retailer photo.
Separate washing from drying
After a wet day, washing a pair and having a dry pair available are two different events. Use your own expected drying time in the trip planner. If the result leaves a shortfall, revise the number of walking pairs or the wash schedule.
Read care before depending on the membrane
Follow the exact product instruction for washing and drying. A routine suited to a conventional merino crew should not be applied automatically to a treated cuff or membrane construction. Waterproof and breathability claims remain the maker’s claims unless independently established for the exact model.
For early rubbing, shifting fabric or a damp change, follow the hot-spot prevention guide before continuing your sock fit experiment.