I use a HVLP spray gun for my canvas. Always wear your respirator when coating canvas!! When I started out I sprayed once without a respirator, I was high for hours. It is terrible for you. Now I use a full face respirator.
I suggest stretching your own canvas. You will make more money and you can ensure the product is perfect. I use to spray the canvas 3 times with PrintShield then stretch. It was really hard to stretch, I ended up bruising my hand trying to get stretch the canvas tight enough. Now I spray it once or twice, stretch it and then coat it 1 or 2 more times. It doesn't crack if you spraying it 1 or 2 good coats, the third is mostly for the finish. I did buy a Canvas Stretching machine, it save a lot of time, blood, sweat and tears...
This is the respirator that I use for spraying lacquer, working with anhydrous ammonia and cutting MDF.