To be honest, I think it's mostly for canvas. I was at the art store and seriously that was one of my only option. Everything else was for oil paintings or stuff like that. I figured: It's a varnish, works with acrilycs... Go for it!
It's supposed to be museum quality protection against fading, dirt, moisture and discoloration. I've stuck my headphones in a bag full of stuff not to long ago and some paint came of from being scraped on something... but just a bit and it was really tight agaisnt the thing so I guess all in all it's not that bad!