I just welded a rear quarter panel on and was thinking of using this as a seam sealer to cover the weld seams and then sand it smooth. Would it be best to paint RustSeal first, then push this epoxy into the seam sand it smooth then top coat with another coat of RustSeal for protection?

It is always best to get the RustSeal down on the prepped metal first (KBS Klean/RustBlast or sandblasting) before using the NuMetal as this helps to prevent pop off.

Within 6-8 hours of the last coat of RustSeal, mix NuMetal Epoxy Putty as directed & apply to repaired areas for smoothing or other parts that need filling. When working with NuMetal, have a bowl of water nearby to dip your fingers into for smoothing out the putty. This will help eliminate or reduce the need for future sanding. NuMetal epoxy putty will cure in approx. 6-8 hours at 75F (24C). You may give the area a light sanding after curing, but be careful NOT to sand through the coating! Afterwards, wipe down the sanding dust from the surface with a clean cloth, and apply a final coat of RustSeal. This final coat must be applied to the repaired areas, but may also be applied over the entire project area if you choose.

Please check out the RustSeal Directions and NuMetal Directions and let us know if you have any additional questions.

Hello.

Have you performed adhesion strength tests regarding the NuMetal?   Iv always thought a epoxy would adhere better to rough mechanical tooth steel than a paint would.  Once you paint the steel, the adhesion strength relies on the RustSeal..

Yes, NuMetal (like most things) would adhere much better to a rough toothed surface versus an ultra smooth surface. But, NuMetal does not stop rust, so if you adhere NuMetal directly to steel with no rust protection in an environment that requires rust protection, you take the chance of the NuMetal popping off. That said NuMetal does adhere excellent to roughed up RustSeal (80-300 grit) which is why we recommend that.

Please let us know if that helps and if you have any additional questions.

Thanks..  I'm trying to decide the best method to build back a rusted roof drip rail on a E350 van.   The back over the rear door vertical section has rusted completely away..

I came across this test showing body filler sticks to steel better than primer first..  So I figured what ever epoxy I choose would be applied to bare rough steel.   But now I'm questioning that approach..

We like that study, but it does not apply here though because RustSeal is not a primer like they tested.