[jcarter]

I am finally getting ready to put some paint on my car.It has had epoxy primer on for a couple of years, while working on it.What grit of paper is adequate to give good adhesion to this? Also what color of scuff pad would I use in tight spots ?I don't want to leave scratches, but I want it to stick! My plan is to scuff it all, recoat with epoxy,to cover bondo and sand thru to bare metal in some areas,then paint with a single stage flat black.( Not J.D. Blitz Black) Thanks Jim.

[jcclark]

I'd use a red scuff pad.
If you're going to re-prime it, scratches shouldn't be a concerne.

[Bee4Me]

Depending on the brand of epoxy,you may need to use 80 to even scratch it and you'll likely use a LOT of it. Epoxy after it cures is H-A-R-D.
Wet seems to make it easier though and especally with the red scuff pads.

[jcarter]

It has Omni MP170 on it, and is pretty hard.I had been wundering about scuffing with about150 or 220 and using scuff pads in the tighter spots.I guess my main worry was"what is recquired in most cases to get good adhesion with a second coat of MP170 ".I was then going to paint the flat black in the time window for the second coat.

[crashtech]

If you are not going to re-sand the second application of epoxy, I think you ought to stay with something fairly fine, 220 might be a good compromise, followed by a rubdown with red pads. Cured epoxy can be tough to sand, but using something rougher than 220 will probably leave a visible scratch in your black topcoat.

[Rag top bird]

I would wet sand with 400 grit and then recoat with epoxy if you have any filler work then you should use a urethane surface primer over that area

[kenseth17]

mp170 states after their epoxy has sat more then 3 days it should be scuffed and reapplied, so I'd apply another coat over everything to be safe and adhere to the recommendations of the manufacturer, never mind rereading looks like that was your plan anyways. I have never let it sit that long, but if you sand your newly applied coat, as long as painted within 3 days, you should be able to use finer paper if only needed to maybe smooth some and knock out dirt nibs and won't have to worry if you miss sanding some spots, cause you still will have mechanical adhesion. Last car I used only epoxy for primer on most parts, and once all was good, sprayed two reduced coats of epoxy as a sealer, let sit overnight, hit with 1000 wet, and started laying base.

[BarryK]

Setting for two years, it should be "Hand sanded" with 150-240 for proper adhesion for the next coat of epoxy. (my preferred choice is 180)

Do not use a DA but just a fast sand job by hand.
It would also be very worth your while to spray two more coats instead of just one for maximum adhesion.

Also note, when done sanding and after washing with wax and grease remover, let the car set for an hour or two before applying the epoxy because of the age.

[jcarter]

Thanks for all of the advise.I have started to hand sand the front fenders with 150 .I don't think there will be any scratch marks, cause this stuff is hard. You guys tell us newbies to get epoxy on our bare metal right away so it don't rust, now 2 years latter, got to work hard to get this so it will accept paint!!!!! My concern is, will red scuff pads be good enough in those"awkward" spots?Does epoxy stick to epoxy that has been scuffed "better" than paint will stick to scuffed epoxy? I guess I am going to do it pretty much as BarryK suggested.I will probably wait a day between last coat of epoxy and the paint.

[BarryK]

A scuff pad to the hidden corners will be just fine.
The sanding only needs to be a fast scuff, not like you would do on a previous paint job where MUST make sure there are no shinny areas.

Could you have just sprayed the epoxy over itself without sanding and it stick.
Test show that works pretty good as epoxy tends to stick pretty good to itself well after open coat time, however there are a lot of other variables that can affect the adhesion so it is best to scuff up and good exercise if nothing else.

[sevt_chevelle]

[QUOTE=BarryK]Setting for two years, it should be "Hand sanded" with 150-240 for proper adhesion for the next coat of epoxy. (my preferred choice is 180)

Do not use a DA but just a fast sand job by hand.
It would also be very worth your while to spray two more coats instead of just one for maximum adhesion.
QUOTE]

Barry,is there any special reason why one should NOT use the DA?
Thanks...Eric

[BarryK]

A couple of reasons, a 180 by hand VS 180 on a DA will give a better tooth mark.
Also a lot of epoxies do not want to sand with out loading up the DA paper.

By hand would just be faster in this situation, I would guess.

However, 180 on a DA would work fine, if the epoxy sands ok.