Seam sealer sticky after undercoating over it

[myredracer]

Feeling a bit bummed... Can really use some help on this one.

Have a body all block sanded and getting close to being ready for paint. I've used Proform seam sealer in a lot of places in the trunk, on the floors and underneath. I sprayed Proform rubberized paintable undercoating over the seam sealer in the trunk area about a week ago. Yesterday I noticed the seam sealer is a bit sticky where the undercoating has gone over it as if the undercoating reacted with the seam sealer.

I don't recall anything in the Proform directions not to do this. Is the seam sealer going to dry up okay a a period of time? I have everything masked off and am ready to spray undercoating under the car and I don't want it to turn out to be a huge problem.

Thoughts?

Thanks!

 

[NYBODYMAN]

Was the seam sealer dry before spraying the undercoating?

 

[myredracer]

Was the seam sealer dry before spraying the undercoating?

Seam sealer was on for over a week, and same for the undercoating now.

This morning I looked at the tubes and realized that one is rubberized and one is urethane. The tubes look the same... I was low on the urethane that I got at a body supplier shop and bought another tube at a retail auto parts on a weekend.

I can't tell for 100%, but almost, that I used the rubber-based sealer in the trunk area. In that case, it could be possible that the solvent in the rubber-based undercoating softened the sealer.

The only precaution on the rubber-based sealer is you can't leave it exposed to UV and shouldn't be used in areas of high mechanical stress. No mention about incompatibility with any other products.

I'm almost 100% too that I used only the urethane sealer on the undercarriage. Not sure if you can tell by looking at it but could do some test spots by dabbing on a small dot on it? I def. know I used the remainder of the rubber sealer on the floor areas inside the car, but I had that painted already and the sealer is fine.

I just called the manufacturer of the sealer & undercoating and the tech. I talked to said he's never heard of the sealer going tacky. He's going to talk to someone in their lab and see if he has some explanation. Hopefully they will come back and say it just needs some time for the solvents to fully evaporate. Good thing I'm a couple of months away from painting when the weather warms up.

 

[FSrepair&fabrication]

Some brands of spray undercoating are garbage. Ive used many that take literally days to dry or never totally seem to dry at all. Rustoleum brand seems ok, but is still slow drying compared to truck bedliner which i use instead most of the time now.

 

[Bottlecapdigger]

I noticed the seam sealer I used took a long time to dry throughly , it got a skin on it but took a while to get solid. ( weeks) Was it still soft when you sprayed the undercoating over top? BCD.

 

[myredracer]

I spoke to the chemist in Proform's lab today. He's going to take some of the rubber-based seam sealer and experiment with it by putting some of the undercoating over it. I may be looking at scraping it out and redoing it. Won't be a fun job if I have to.

It turns out the date code on the tube is actually 2011!! That might be the cause right there. It spread okay when I used it, unlike silicone caulk or PL400 which hardens and it wasn't tacky to the touch the next day.

I should have waited until the Monday and gone back to my body paint & supplies place and gotten the good stuff.