ParamountPaint, you mention a very interesting thing about new drywall, dust. I do not say that getting the majority of the dust off new drywall is a bad thing and I do that myself, but the really neat thing about Gardz (and I imagine the same for Draw-Tite and a couple of other sealers) is that it doesn't just seal the surface. It soaks through any dust remaining and goes into the drywall and saturates it because it is thin enough to do so. It is a sealer, plain and simple, no pigment to thicken it up. The dust on the surface literally becomes a part of the surface.
I would ask anyone here if they know of a better product to both seal a surface AND make dust a part of the surface so that a tape test will not even be affected by dust. I have heard that Draw-Tite is thicker than Gardz, so in this respect it might not be a good at binding the dust into the wall.
I will repeat my initial experience with Gardz. I used to strip and wax (acrylic finish) floors. The acrylic finish was milky white, smelled of banana oil and was thinner than paint. Early on in my floor refinishing days I stripped an old floor, then started applying acrylic floor finish. One coat, two coats, three coats - it wasn't covering, it was flashing. I went to my janitorial supply house and asked for help. I was told that on an old, porous floor, I needed to put down a sealer first, then the top coats would shine like the sun. I did this with the job I was having problems with and, voila! The top coats did not soak into the floor, but shined it up going over the top of the sealer.
DeArch has said here that Scotch Paint in CA took a concrete sealer and reformulated (did they, or did they just use it straight up) it for use on torn and damaged drywall, usually after stripping wallpaper. Zinsser wanted to buy the rights to Draw-Tite, but Scotch wouldn't sell, so Zinsser made their own version, Gardz.
When I first used Gardz I looked at it and thought "this looks like acrylic floor sealer." When I smelled it, I thought "this smells like acrylic floor sealer." When I used it and saw it's viscosity, I thought "this has a similar viscosity as acrylic floor sealer."
To be fair, I have not used PVA since I misused it back ion the early 80's and had to strip it off what I was doing. PVA may very well work in the manner for which it was intended for, but I would be very surprised if it could solidify surface dust into the wall or ceiling like Gardz does, then provide a moisture barrier that lets the water in the paint wick off into the room instead of being sucked up into the surface being painted such that when you finish the wall or ceiling you started to roll, the starting point would still be wet and you would not be struggling to get roller lines smoothed out before the water in the paint gets sucked into the surface and you are left with sanding them later and recoating.
As far as super-lightweight compounds go, the GC I am currently working for uses a USG blue top that dries yellow. I can practically sand it with my eyes. I can certainly sand it with my bare hand. I like to use Gardz on this so it hardens it so it doesn't dent easily.
I guess what I am trying to say is that if you haven't used Gardz for sealing drywall, you should treat yourself to the experience. You may come away feeling that it is not necessary for your line of work, but until you try it, you will not know how it works.
I guarantee that if you use 2 coats of Gardz on new drywall, you will have the best experience in putting the finish coats onto your walls or ceilings.
I have to go now. They are telling us that lights are off in 10 minutes.
futtyos