I used to fight with filler shrinkage on big jobs until I switched to polyester glaze instead of metal reinforced bondo

Man I spent years sanding back low spots after filler dried on quarter panels and roof repairs. About 6 months ago a old timer at the shop I freelance at told me to stop using the heavy stuff for thin coats. Switch to glaze for the final skim coat before primer. No more shrink back. I can spray primer the same day now. Anyone else deal with this or am I just late to the party?

3 comments

3 Comments

parker_hall53d ago

That 3m platinum glaze is the one I've been messing with lately, but I'm curious about how thick you're laying it on for those final passes. I gotta ask though, are you doing anything special with the hardener ratio to keep it from shrinking, or just mixing it normal like the bondo?

the_drew3d ago

The 3m platinum is good stuff but I keep it thin on those last passes, maybe 1/16 of an inch max. Anything thicker and you're asking for pinholes or shrinkage down the road. I just mix it like the can says, no special tricks. People mess themselves up trying to stretch the hardener or cut it with acetone, just follow the directions and you're fine. You get those tiny bubbles if you lay it on too thick and then you're sanding twice as much, so thin coats and patience work better for me.

grantnelson3d ago

Picked up a quart of that 3m platinum last week actually and I've been messing with it on a fender repair. I'm not doing anything wild with the hardener, just the normal amount the tube says. I mean maybe it's just me but I think people overthink the ratios and end up making problems where there aren't any. What gets me is I used to buy the cheap bondo from the auto parts store and wonder why my work looked like garbage after a month. The glaze lays down so smooth you barely have to sand it if you get it right. Idk I still use the heavy stuff for big dents but for that last coat before primer I wont go back.