I have not tried it for watercoloring, but love to use my spectrum pad or regular pad and brayer on it.
You can use a versamark and do a resist (stamp image in VM, then sponge or brayer over it and the VMed image will resist the ink)
Glossy is great for special techniques-like polished stone, drunken chalks, etc. (you can go to the resources section and get more help for those techniques)
You can also use it to emboss on wioth a regular pad. Since it has a sleek surface, the ink stays wet, so any dye pad can be used to emboss with
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I know there are a lot of other ideas wih it, but that is what popped in my head right away-HTH