sanding epoxy

[mongocanfly]

while sanding my epoxy around my body work and just general panel sanding there's a few spots I've cut thru the epoxy and can see metal...what's the best approach when this happens....I've been using sandable duplicolor rattle can body primer for my guide coats....would it be ok to just hit these areas with it or do I need to put something else on it...like etching primer....hopefully next week ill be spraying high build....that's the plan anyway...

[Foot Stomper]

Epoxy primer should be left alone unless it needs a scuff to top coat with urethane primer as per the manufacturer's technical data sheet. If you have sprayed the epoxy, then worked on some areas for rust or general body work, and in the process sanded off some epoxy, you will need to reapply more epoxy to the bare steel areas.

Stay completely away from Duplicolor sandable primer... stick with 2k products only. If you want a guide coat, get the 3M charcoal puck or mist black aerosol paint on the panel....and I mean mist... stand back 3 feet and haze the panel in 2 seconds... sand a little of the high build and you should see a lighter color immediately, do not over do it! Epoxy primer does NOT NEED guide coat.

[mongocanfly]

well the epoxy needed sanding...I had some orange peel to deal with and then around the body work....ill touchup spray epoxy on the areas I described....but even the sherwin williams guy told me to scuff the epoxy unless i was painting very shortly after epoxy....im still looking at a month or so til paint...sanding it really smoothed the epoxy...and the guide coat was for my body work areas....I've used the duplicolor before as a guide coat on other trucks with no issues....but point taken
once the high build is on my plan was red scotchbrite before paint..I saw where K.C. was using the red along with 3m scuffit gel right before paint...so that's the direction I was heading....bear with me ...I'm still learning and kinda green to all this correct process paint stuff

[sprint_9]

Spot in epoxy over your filler and bare metal.

Make sure you read up on your recoat windows, if you dont spray 2k until next week you will most likely need to sand or scuff the epoxy before you put down 2k. If you dont you will most likely have adhesion issues.

Looks like you have most of that covered.

[mongocanfly]

Sprint,,I've seen it told both ways...your saying put epoxy over bodywork and I've also seen the argument that its only for bare metal, not over bodywork...... if it won't hurt anything ill spray epoxy over the body work...or not....

[sprint_9]

It may depend on your epoxy. Im used to using a certain brand so Im not sure what the in's and outs of the stuff you are using. Does your specific product list anything about this type of scenario on the tech sheet?

That being said the way I see it is epoxy seals, and body filler is porous, so sealing that off from anything above is a good thing. It gives you a good uniform surface to move onto 2k with, and also allows you to glance at your repair area and catch something you might have missed. Once you go to 2k primer you really dont want to be doing any more filler work, so this glance at your repair can be an important step.

[mongocanfly]

I'm using all Sherwin Williams products on this truck....I read the data sheet several times but don't recall anything about spraying over filler..

[sprint_9]

What epoxy specifically?

[mongocanfly]

SW dimension dp210 dtm epoxy

[sprint_9]

SUITABLE SUBSTRATES
· OEM Enamels
· Aged Refinishes
· Cold rolled steel
· Hot rolled steel
· Aluminum
· Fiberglass
Note: Dimension® DTM Epoxy Primer DP210 does not require an etch primer and can be applied directly to any properly cleaned and sanded substrates with 220 grit sandpaper.

I see no problem spotting in over your entire repair given the above info from the tech sheet.

[sprint_9]

Originally Posted by mongocanfly

once the high build is on my plan was red scotchbrite before paint..I saw where K.C. was using the red along with 3m scuffit gel right before paint...so that's the direction I was heading....bear with me ...I'm still learning and kinda green to all this correct process paint stuff

Once you are done with your high build and have it sanded to 320/400 (solid color) or 600 (metallic) you can hit any non sanded areas with a red or gray scotch brite depending on the type of base you have. From there it is wise to go with a sealer, Sherwin Williams has a couple diffferent ones in the dimension line that you are using. The sealer will fill the scratches you have from above, it then has to be base coated within a window, but when done within that window you dont need to re-sand or scuff. The base will bond to the sealer and you will have a more uniform and stronger finish less prone to stone chips than if you were to base coat right over 2k high build.

[mongocanfly]

don't know if it makes a difference but I'm using single stage paint
I'm pretty much going step by step with what the SW rep is telling me but I'm not against any other advice....

[Foot Stomper]

Mongo, when you work a small area with filler, you end up scrubbing off any epoxy in the adjacent areas...this is why its reccomended to reapply epoxy to those bare steel areas...its not about applying epoxy to filler... it's about protecting the steel.

It's very simple, bare steel needs epoxy. Once you have epoxy on bare steel, you're good... remove the epoxy means have to reapply. Protect the steel with epoxy, nothing else matters, unless you remove the epoxy.
Brand of epoxy is completely irrelevant!

The kind of brand of filler, high build primer or paint (topcoat) is irrelevant after you have any brand of epoxy on.

[mongocanfly]

10-4....thanks guys.....

[CC69Rat]

Think of the epoxy primer as a 'seal' to protect the metal. Ive done it both ways actually. Bare metal, 80 grit and body filler to take care of low spots then epoxy over all of it, and I've also done what youre asking. Knock down the Epoxy with 220 ( I use Scotchbrite as someone else mentioned) 80 grit over the places you need a glaze and/or body filler skim coat to get it slick then another layer of epoxy to cover the bare metal spots. 2K primer is porous. The primer will allow water to penetrate it where Epoxy wont. The 2K primer directly over bare metal basically the metal will rust from the inside out. It will start to bubble your primer and base underlying coats after a while. Epoxy primer will keep the metal protected ( Non porous)

The problem is Epoxy usually has a recoat window. Spies, Southern, PPG is usually 7 days. Anything beyond that the Epoxy is going to get so hard the next subsequent layers wont bond to it. That's what the others have mentioned about Epoxy, on Epoxy. That deep into your paint job you dont want lifting in a few years. You want that paint and primer bond to be as strong as you can.

I usually just dolly out everything and get it as close as I can to perfect. 80 grit the areas that need a skim coat, and put the body filler or whatever on it. ( I use Rage, Q1, etc.) then once you get the panel dialed in and really close, go to Epoxy to seal it back. Once the Epoxy has dried, within the recoat window I will knock it down with 220 and go straight to 2K primer ( I really like Southern Polyurethanes 2K primer.. just saying)

Get it slick, block it, sand, recoat (super light) , guide, sand, recoat (super light), block again. yeah.. I block to 500 for single stage non metallics, and 600 for metallics. The metallic will fall back into the sand scratches anything below 600.

I really like single stage. You can block it to as slick as glass (non metallic) , you just wont have the UV protection like a base clear job. I have sprayed clear over single stage too.. but ..