Do I sand epoxy primer before filler?
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Hey guys
I just primed my hood grill and the lip of my two front fenders yesterday and I’m moving on to the filler stage.
I was just wondering if epoxy primer needs/should be sanded before applying filler? Or can I just put the filler straight on without sanding?
I did two coats of epoxy primer on the bare metal, then I’m going to use filler, then I will put two more coats of epoxy primer to seal it in.
Thanks guys,
ElliottDepends on what brand you used,check the tds sheet to be sure.Epoxy doesn’t sand very well as a rule so you might want to use a 2k urethane primer on top of one coat of epoxy after it has flashed.We need more info before we can give you an accurate answer.You can also do filler work over properly prepared bare metal also.
Hey here’s the spec sheet. It’s PPG but their industrial line.
I don’t really have any 2k urethane primer…bleh…
Never used it can’t comment,looks like industrial or from delfleet division.Whats wrong with 2k urethane primer?
[quote=”Jayson M” post=26552]Never used it can’t comment,looks like industrial or from delfleet division.Whats wrong with 2k urethane primer?[/quote]
Nothing…I just don’t have any and don’t really have any time to go buy any…
Anyway…back to my original question, should I be sanding the primer prior to using body filler on it?
Phone PPG directly,they can give you the best answer.
I’ve used that stuff before (sorta like their cheaper polyurethane, very similar to Endura, but crappier). It is an epoxy, but much thicker than traditional automotive epoxies. It has some filling and sanding ability, but no replacement for 2k urethane. I believe its filling abilities are more intended for sandblast profile and minor metal work imperfection on industrial parts.
Personally I wouldn’t have even considered using this on an automotive application 🙁
In any case, I would grind it off, back to bare metal anywhere you want to fill. Not the same type of automotive epoxy you can fill directly over.
I use the PPG DP epoxy all the time. You can fill over it without sanding during a certain window of time. I am uncomfortable with that so I scuff it with a red scotchbright pad then fill.
Epoxy doesn’t sand well but if you use some 330 per cleaner as a lubricant and some 220 or 320 it will sand real nice without loading up the paper.
Both methods work real well and I’ve never had issues with either process.
sounds a bit arse about face to me lol,i always fill first then prime ,the trouble with filling over fresh potentialy non cured paint is that the paint be it primer or whatever is liable to shift or shrink under the filler which tends to not move ie your putting a very stable product over one that isnt so stable ,done the other way round the paint or primer can move and cure out evenly ,in the case of epoxy i use it wet on wet with a topcoat of high build 2K primer, as has been mentioned epoxy doesnt sand to well so laying 2K over it wet on wet saves a lot of headache
wet on wet being after the epoxy has dried out but before it has fully cured out so it will cross link ,i once made the mistake of laying my 2K primer too early and the epoxy would not cure underneath ,i then had to strip the whole job off
Paul
Hey.
I see. So basically you have to shoot the 2k before the recoat window closes (7 days), but after 30 minutes, as it says in the tech sheet I posted?
Thanks,
ElliottYep, basically.
Or just sand/scuff it with 320 grit/red scotch brite pad, any time after it is dry. I would probably sand it anyway, just to be safe (even if you are still in the recoat window).
I would wait 1-2 hrs too be sure the epoxy is cured enough. You dont want to spray 2k too soon and epoxy might be still wet underneath.
I always bomb through it with 220 or so on a DA to scuff it up for filler. then work over the little dimples and whatnot with red scotchbrite.
I would much rather have epoxy on bare metal than filler.
[quote=”bobwires” post=26600]I always bomb through it with 220 or so on a DA to scuff it up for filler. then work over the little dimples and whatnot with red scotchbrite.
I would much rather have epoxy on bare metal than filler.[/quote]
I understand the idea of it, but don’t completely agree. Most of the better body fillers have additives to allow better adhesion to bare metal as well as offering corrosion resistance. If you use a quality product and apply it properly, I don’t think it is worse than applying filler over epoxy. And then you eliminate any chance of there being any issue with adhesion between the filler and epoxy.
Alright so with quite a bit of help with the sanding to get it all semi-flat…I sprayed more primer on everything…maybe it’ll be the last coat…will have to wait to see after I wet sand it all…but it looks good so far!
[img]http://184.154.165.18/~devilthe/uploads/1340527746.jpg[/img]
[b][size=150][color=#FF8000]Anyone know where to buy the undercoating stuff they put on the bottoms of these?[/color][/size][/b]
[img]http://184.154.165.18/~devilthe/uploads/1340475808.jpg[/img]
[img]http://184.154.165.18/~devilthe/uploads/1340557221.jpg[/img]
[img]http://184.154.165.18/~devilthe/uploads/1340525601.jpg[/img]
Elliott
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