What kind of opaque watercolor did you use? Acrylic or gouache? Chinese White?
When I use gouache, I usually call it that or opague watercolor. When I use acrylic, I call it an acrylic - even if there is transparent watercolor underneath. But that's just how I choose to state it.
There is spray made specifically for watercolor canvas that fixes the painting so that you can frame it like an oil - no matting or glass. Perhaps you can go to Fredrix's web site and fine more out about framing.
Anyone else out there been painting on watercolor canvas? How do you fix and frame these?
Well, I'd say it's watercolor and gouache, or if you wanna make it simple.... opague watercolor.
I haven't used that particular spray myself, so read the manufactuer's instructions. If it were me, I'd spray a light intial coat on to fix it and then a second coat when that's dry. I get nervous when I suggest things I haven't used myself.
I use Golden UV resistant spray and varnish for my watercolors but they're on paper. I tend not to frame with glass.