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-   -   SEM multi purpose panel adhesive (http://www.hotrodders.com/forum/sem-multi-purpose-panel-adhesive-232872.html)

tech69 05-14-2013 11:40 AM

SEM multi purpose panel adhesive
 
so we got a showcar vette that came a few months back with a bad SMC bumper. The old man used The SEM multi purpose panel adhesive on the front and back to stiffen it up then piled on kitty hair on top. It bubbled. To fix he just feathered the area and added more panel adhesive. not sure if he's gonna kitty hair it again but I think it's gonna fail again if he does. Shouldn't he have strengthened this from the back with perhaps the panel adhesive and maybe a piece of sheet metal to strengthen it? I would think a polyester based filler would have issues with SMC AND the panel adhesive caked all over the bumper. Seems like your 3m rigid parts repair would have worked on top with panel adhesive to stiffen it up on the back side and only used as a backer.

So my question is, is there huge issues with an SEM multi purpose panel adhesive(epoxy based) used as a filler of sorts over SMC? I would think the bond to the SMC would be good but top coating AFTER can be tricky on top of expansion and contraction rates. Just thinking maybe it's safer to use a 3M rigid parts repair over the SMC instead of a panel adhesive and use panel adhesives as only a backer, NOT something under the surface.

My next question, what SMC filler do you recommend? and can you top coat it with a little flexible filler for finishing touches? We have 3m Rigid parts repair material at our local jobber and it's epoxy based but can it top coated with a little flexible filler?


not trying to be the shop superhero here but I've kind of been waiting for this to happen cause I cringe when I see old guys throw kitty hair over everything. Just trying to hint at some things in hopes this doesn't come back again. I tried to explain it in a nice way but talking to old guys with more experience than you isn't easy when they're wrong. :)

BarryK 05-14-2013 12:26 PM

You NEVER apply any type of filler over a two part bonding adhesive.
Will bubble every time.

If you want to apply a filler or a thin coat of a glazing putty, you use epoxy as a barrier coat.

Why would he think he needed kitty hair over it? he had all the strength he needed with the 2 part????

tech69 05-14-2013 12:37 PM

he's one of those guys who says, "when in doubt just kitty hair it!" :D


I think the filler was for waves.


Thanks for the advice. I'll suggest he seal it off with epoxy before top coating.

So the 3M Rigid parts repair can't be topcoated with fillers either ?

BarryK 05-15-2013 05:30 AM

He needs two coats of epoxy and it should set 24 hours in a perfect world before applying a skim coat of filler or 2 part glaze.
Kitty hair may or may not stick to the epoxy, so not a good choice and not needed.

Best of luck shoving this down his throat! LOL

tech69 05-15-2013 07:49 AM

he decided to use SEM problem plastic repair over the caked on panel adhesive and flexible filler over that. I think the outcome is great. I mention something about it so when it fails again maybe people will listen.

BarryK 05-16-2013 05:40 AM

Quote:

Originally Posted by tech69 (Post 1675758)
he decided to use SEM problem plastic repair over the caked on panel adhesive and flexible filler over that. I think the outcome is great. I mention something about it so when it fails again maybe people will listen.

I say, it will bubble in 8 hours to 7 days of full sunlight, it will be fine as long as inside.
What do you think 69? If your boss is a betting man, you might win some money on this one.

tech69 05-16-2013 08:48 AM

he only stripped the kitty hair off the problem areas. The rest of the bumper still has kitty hair all over it. Stubborn.

mitmaks 05-17-2013 12:35 PM

I would've used SEM bumper repair #68422, great stuff
Then I use Polyflex to fix any pinholes, uneven areas and shoot 2-3 coats of 2K primer and sand it down and it's ready for paint
http://www.evercoat.com/imgs/products/Poly-Flex.jpg


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