Seam sealer question. - PeachParts Mercedes-Benz Forum

Clemson88 · #1 12-18-2021, 11:02 AM

I'm about finished with the rust repair and have a couple lap type joint and some areas which are butted together and spot welded to hold.

I know nothing about seam sealer other than understanding that many folks have graduated from the quarts of semi liquid sealer to the caulk type tubes of 2K sealer.

While I suspect the ease of application which makes cleanup almost not necessary I wonder if having a two part product is much better than the brush on type from the quart can.

Can those of you with better understanding provide your opinions on this subject?

Clemson88 · #2 12-22-2021, 01:45 PM

Perhaps some advise for those who intend to repair rusty metal with replacement pieces.

I have prepared all the sheet metal replacement pieces by sanding with no finer than 180 grit according to instructions of most 2K primer producers. Joint which lap or have flanges with contact surfaces which will spot weld together have been painted with Transtar 2k epoxy primer before welded into place.

No other areas will be painted until the pieces are in place, the welding on them is complete and surfaces are prepared to prime. I am not grinding welds down on parts which can not be seen.

I drilled a spot weld hole in one of the pieces then used a drill bit which was cut blunt to clean the other part butting to it so welds would be efficient.

I will paint the parts which were not primed before the welding was done and scuff them for a coating of sealer in places which sealer are needed.

For the underside of the body I hope to afford a thick 2K sealer applied with the proper caulk gun and wiped by latex gloved hand dipped in wax and grease remover. I will also use this sealer on the dimple where the rubber drains rest in the trunk wells beside the spare tire well (area of drains and drainage). This thick sealer has to be forced into place. If you don't put it there, it won't be there and you'll trap oxygen and moisture beneath the sealer.

I have at least on place where I'll need to shoot a bit of the self leveling 2K sealer. Shame, 40 bucks to seal a couple spots.

It appears the use of masking tape is critical to have nice seams. Fortunately, none of what I'm sealing at the time is exposed to the eye. I expect a more serious and complicated process when I clean and reseal the ditch drains running down the sides of the roof on this car.

Since I started this thread I thought I'd share my research.

Hogweed · #3 12-24-2021, 12:27 PM

thanks! i have a floor repair coming up and i'm sure i will use that spot welding technique

Quote:

Originally Posted by Clemson88

Perhaps some advise for those who intend to repair rusty metal with replacement pieces.

I have prepared all the sheet metal replacement pieces by sanding with no finer than 180 grit according to instructions of most 2K primer producers. Joint which lap or have flanges with contact surfaces which will spot weld together have been painted with Transtar 2k epoxy primer before welded into place.

No other areas will be painted until the pieces are in place, the welding on them is complete and surfaces are prepared to prime. I am not grinding welds down on parts which can not be seen.

I drilled a spot weld hole in one of the pieces then used a drill bit which was cut blunt to clean the other part butting to it so welds would be efficient.

I will paint the parts which were not primed before the welding was done and scuff them for a coating of sealer in places which sealer are needed.

For the underside of the body I hope to afford a thick 2K sealer applied with the proper caulk gun and wiped by latex gloved hand dipped in wax and grease remover. I will also use this sealer on the dimple where the rubber drains rest in the trunk wells beside the spare tire well (area of drains and drainage). This thick sealer has to be forced into place. If you don't put it there, it won't be there and you'll trap oxygen and moisture beneath the sealer.

I have at least on place where I'll need to shoot a bit of the self leveling 2K sealer. Shame, 40 bucks to seal a couple spots.

It appears the use of masking tape is critical to have nice seams. Fortunately, none of what I'm sealing at the time is exposed to the eye. I expect a more serious and complicated process when I clean and reseal the ditch drains running down the sides of the roof on this car.

Since I started this thread I thought I'd share my research.

Clemson88 · #4 12-25-2021, 11:24 AM

Since I struggle with welding in odd places I considered painting both sides of both components, clamping them together, drilling a hole and backing it with a thick copper plate and welding it as is. The penetration wouldn't be an issue if the arc is always struck on the flanges rather than the copper.

On butt welds which are hidden I stitch weld both sides and if the seam is to be finished to the eye I only work the weld down smooth on the side seen. It is very difficult to stitch weld without missing a spot or working the weld smooth to see the tiny holes. If I don't grind the weld I wire brush it with a drill, wipe it with wax and grease remover then 91% iso alcohol, and shoot a three or four light coats of well thinned 2K epoxy on it.