Seam sealer melts Zero Rust
I was very disappointed the other night. I had applied Zero Rust over my beautiful newly replaced floor pans. I let if dry for at three days. I then went on to apply 3M brushable seam sealer. The seam sealer started melting all the Zero Rust. It eventually dried back as one but any areas the required more than a few brush strokes got very messy fast and made the entire job look like a mess. Is this normal? I have used Epoxy primer before and of course did not have this problem. I was hoping that I could use Zero Rust on fresh metal and avoid having to breakout the spray gun equipment and all the cleanup that goes with it. Need help please.
I've never used the 3M brushable seam sealer so I can't comment on that. I'm sure someone else has and will comment.
What I have used over Zero Rust has been the Fusor 300EZ seam sealer and have not experienced the problem that you have. I've used both in hot (90), warm (75) and cool (60-65) temps. I usually do two coatsof Zero Rust, first the red oxide and then the black. Then after the Zero Rust has dried the seam sealer is squeezed from the tube and spread with a small brush as appropriate.
You don't mention what the temp was at night when you applied or how many or the types of coats. I have noticed that at the cooler temps it takes longer to cure and if applied too thickly the Zero Rust wil still be soft under a thick coat. This has been when the temps are below 60 degrees.
The 3M Brushable Seam Sealer is solvent based and the ZR is not a hardened product so it's sensitive to solvents attacking it. We stopped using that sealer years ago because it hardens and cracks. If you use the a Fusor product you won't have that problem and it holds up MUCH better.
Originally Posted by merbesfield
Another thing you need to watch out for is to allow the ZR to dry between coats. Since it's a drying product and not a hardening product if you apply too much too fast it will dry on top trapping the solvents underneath and this will make it take forever to dry.
Well, I think that is exactly my problem. ZR went on think and did not have time to dry. So now the next question. Can I leave the 3M product on and go over it with another brand once it cures? I have used Wurth brushable seam sealer before. The seams on this project are huge so they will require two more quarts along with some tubes as well. The only product I have used is Wurth's. How about Fusor, will it go over the 3M? Of course, now my beautiful metal work looks like someone puked on it, but I guess once I undercoat it, it will cover up. Which is the next question, which undercoat brand to use? I have a Wurth Multi spray gun or I could purchase a basic shcutz gun for other brands. Thanks for the advice.
The 3M sealer takes a LOOONG time to cure because it has solvents deep inside that will escape over time but most should be gone in about a week of warm temperatures IF it was applied thinly. If you apply a "good" sealer on top of the 3M sealer you will trap the solvent in the 3M and it could cause problems later so try to have a pretty dry 3M sealer before you apply the good stuff or remove the 3M sealer. We use Fusor on almost everything that needs a good seal, it adheres well, remains flexible and will outlast the car.
Originally Posted by merbesfield
We rarely use undercoating for the same reason we don't use 3M sealer, most are solvent based and get brittle, crack and trap moisture against the metal. About the only thing we've heard that works good as an undercoat is either 2 part truck bed liner or Fusor spray seam sealer. We usually apply another coat of Zero Rust after our sealer and leave it at that.
If you have wide gaps to seal the Fusor sealer below can do a great job.
Why me!!!! I may need to dig out much of the 3M seam sealer bc I used it to fill the large voids in the corrugated metal floor pans so much of the spots are very large and deep. Our shop is cool now so curing time will be a long time. About the undercoating issue. I thought there were many good undercoaters these days that did not crack like the older ones. I have seem many good reviews of the Wurth SKS stone guard and it looks like the factory. Can you clarify if there are others that you might sell. The Wurth stuff is pretty expensive. I know Upol sells some that is supposed to be good also. Thanks
Originally Posted by Len