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It is simply just clay. Clay is very water-impermeable in general. This is the reason unfired and unglazed pots can be used to hold water. Some of the water will be absorbed by the clay, but this is a slow process, and will generally only affect a shallow layer on the surface for the short times shown in the videos.


1

I have had an old pair of work boots do this, I used shoe goo [what I happened to have] and they lasted months longer, I am less sure if I would trust it for a hiking boot. It will depend on what kind of terrain weather and distance you normally go. If you mostly hike in good weather, easy trails and less than a few hours long, sure go for it, worst comes ...


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