lot vintage brown cotton string rug thread, carpet warp weaving cord yarn

Lot of vintage cotton rug warp (a string-like yarn, probably Maysville?), in 4" tall spools - eighteen full spools and four partial spools in the lot. These are marked 'boilproof'.

This has all been stored away for many years, and the outer wraps are discolored and dusty. The thread is very strong and supple, though.