Gummy Primer

I sprayed on some Rustoleum 2-in-1 Filler/sandable primer on my latest project.

I *may* have been a little overzealous with some thick layers.

It's been about 48 hours and it's still soft - if I try to sand it, it gums up the sandpaper pretty quickly, and I can scrape it off with a thumbnail. It's been sitting in a cool (35 to 70F, we've been having some weird weather) garage. Is it worth letting it sit for a few more days to see if the paint will harden up, or just go through a bunch of cheap sandpaper and get it off and start again?

I would definitely give it a few days and see. Could harden more slowly in the cool weather, and very heavy layers could take longer (although I have never experienced this problem; normally that stuff is done within a day or so).

In any case, sanding all that off and starting again doesn't sound like much fun, so I'd give it every chance to proceed normally.

I would wait. Are you planning on flying it next week? If not whats the rush? Next time use Duplicolor and you will be able sand 20 minutes after spraying. Thats why its $7 a can. You get what you pay for. Sands like butter

Wait, maybe move it to a warmer area?

-Bob

I use a small half bathroom for this -- turn on the exhaust fan and open the heater vent, room gets pretty toasty overnight, fumes go up and out.

Multiple thin coats is the answer. They dry quickly then another coat till finish is achieved.
Also a good quality primer. I get mine from Auto parts store. Duplicolor is good.

I use the same primer have for years now. If it gets to thick it will take a long time to dry, will clog paper if not dry. if I am using it to fill, I will leave it sit for 2 weeks while I am gone for work. Otherwise just like Cowboy said, thin and many layers.

Thin and many layers is all well and good for next time. As for this time, bring it into the house and wait. Be prepared to wait a good while.

It's now many days since the original post. I would assume that it has fully cured by now?