Quick note before heading to bed - I don't *think* a sharpie should impact strength, different kinds of dyes, not so sure. What I can do is get some tensile tests of fabric ready and let them sit for 24 hours, 72 hours and maybe a week (?), see how the fabric performs compared to my baseline tests done last year.
Ah, and good news. My fabric waterproofness tester is almost done, and I hope to unveil it here on HF and else-ware soon!
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