Epoxy Fillers

[Skiertaz]

Hey guys! Not being Picasso with a welder and grinder - and really sucking as a painter but trying to get better - after welding the pinch seam that runs down the length of a 65 C10 bedside (red arrow in photo), what material/ filler stack is recommended to get everything smooth for paint?

I've read of people using JB weld, VPA, lead and regular filler but with no real long term results reported. The bodyline does flex in this area (which opens the gap if a rigid body filler were to be used), especially when the bed side is persuaded to fit the tailgate using the panel to truck frame support rods. I think this may cause body filler to crack.

I've read multiple posts on the forum cautioning against shrinkage, urethane wave, ect when using polyester or urethane based fillers/ high build primers. I've experienced these issues and unfortunately the the nervous breakdown that follows after spending months of sanding, blood, sweat, tears and bags of money - only to find the weather conditions of the day make the final final finish range between T-rex skin and glass.

• What product do you pros recommend to fill a flexible sheet metal seam which isn't completely sealed from behind and needs get blocked with the rest of the panel?
• The guys using 100% epoxy fillers - are you using an epoxy marine fairing compound in place of lightweight body filler? Does marine epoxy fairing compound play nice with the typical automotive refinish stack?
• Does a polyester high build primer have issues with cracking when applied over a more flexible base layer like epoxy?
• Can a high build polyester go over 870VPA without cracking issues down the road?

Sorry for all the questions, I'm just trying to learn best practices for show oriented finishes to help make my paint work better.

 

[fakky]

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[theastronaut]

I've had good luck with SEM 39377 two part sealer for seams like that. Scrape and sandblast the seam to clean out any old paint/sealer/rust, shoot 2-3 coats of epoxy to seal the metal (turn the pressure up, volume down, and fan down to a round circle to get epoxy deeper into the seam), then apply seam sealer. I use a 1/8" welding rod with sandpaper wrapped around it to sand an even radius into the sealer so it still looks like a seam but is evenly shaped front to back. You could leave the sealer high and sand it flush if you wanted a smoother look but I would expect it to ghost the seam after its painted.

I wouldn't weld a seam like that- it will shrink the outer halves of the flanges and pull the bedside concave, and concave panels magnify any imperfections like orange peel and urethane wave like crazy.

 

[Skiertaz]

Thanks, I'll definitely check out the SEM sealer. Any recommendations to get a good finish if I was impatient and already welded the seam

 

[Skiertaz]

Back to one of the original questions - the guys using epoxy body filler, what product are you using and what makes it better than the process/ products from the SPI perfect paint procedure?