I conducted an experiment to see if the primary elements pigments when mixed with various varnishes would stand up to outside weather, mainly rain on a piece of Powertex conditioned fabric which was more than 3 weeks old.
I put the piece of fabric in the border and waited for it to get rained on. After about two hours it was wet and the water just sat on top. I tried rubbing the pigment whilst it was still outside in the rain on all 3 strips and nothing happened, it just stayed where it was.
So I brought it in and absolutely soaked it under the tap and scrunched it to screw out the water. Again I tried rubbing and nothing happened. I dried it with a heat tool.
This is the same piece recycled and dried. On this photo the colours don't look as vibrant as they did before I started the process, but that is because it's still raining and it's got darker, I can confirm that IRL it is exactly the same as it was when it first went outside.
Result, Americana Triple Thick Glaze, Folkart Textile Medium and DecoArt Media Satin Varnish are all waterproof when mixed with primary elements pigments and adhered to Powertexed fabric.
This was taken just now (next day) in the sun and as you can see it's as good as new.