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1st bc/cc -- epoxy prep help needed

13K views 96 replies 11 participants last post by  grouch 
#1 ·
Blocking with 220, sand-throughs, glazing questions.

I've been sanding (wet, block) my epoxy with 220 to get ready for 2k primer/surfacer and have cut through in a few small spots. There are a few places, also small, where I missed some high spots and the epoxy is nearly transparent by the time it's flat.

Should I just spray some more epoxy on each of these before going on to the 2k primer/surfacer or do I need to shoot a complete coat of epoxy? If I shoot a complete coat, will the 220 be a factor, versus the 80 that seems to be the norm for prepping for epoxy?

Background and tales of screw-ups:

This is my first attempt at basecoat/clearcoat. It actually started over 2 years ago, but things got in the way. The car says 'Fox' on the label, but it's really a lab rat -- I'm using my wife's car to learn how to do bc/cc for my real project. She set a low threshold ("As long as it shines") but I want to learn to do it right.

The epoxy is EPX-900/901, from some advice given to me by baddbob 'way back when I was trying to get the hood protected. data sheet (PDF) That data sheet shows beige, gray, black and white, but this stuff is close to Caterpillar yellow.

I shot 2 coats on mostly bare metal and then sanded most of those back off because (a) it was a mess and (b) it was far beyond any reasonable stretch of the recoat time.

After getting 2 decent wet coats on and waiting a day, I blocked with 80 and did filler work with Evercoat Lite-Weight. That was cut down with 40 and then 80. Well, that was the intention. Work was interrupted, I was in a hurry when I got a chance to get back to it and I ended up spraying a coat over some filler that had only been hit with 40 grit. It was hideous.

I'd already mixed enough for 2 coats, so I shot 'em and then sanded the whole thing back down flat. My whole garage floor turned yellow. The only good thing about the waste was that blocking it again showed a low spot I had missed before. It was right beside a high spot on the roof that's half way around a dimple. All together the area looks like a quick-frozen ripple in a pond -- dimple, wave crest, wave trough. After blocking that, it looked like a light blue smudge beside a yellow one next to bare steel.

Now I have 2 good coats over the filler, not counting the bugs. The tech sheet (PDF) for JP202 primer/surfacer says prep with 180 - 240 grit, so I started blocking with 220. I've cut some edges all the way to the metal and sanded really thin near some others.

My intention was to spray the JP202 at 4:1:1 (recommended by Janet at "The Bodyman's Friend" where I bought all the supplies) to get a better color under the base and to act as a sealer over some Icing that I'll need to fill where the bugs died. That local PPG supplier doesn't even stock the JP385 2k sealer, so I'm guessing none of the local body shops use it.

I was told that not using a sealer over the Icing and primer/surfacer will cause areas coated with Icing to be visible through the basecoat. Does that sound reasonable?

I've also been told that the color I've chosen, a VW "Tornado Red", will show every flaw I leave behind. Oh, well, it's a learning experience. Besides, another screw-up on my part regarding a list sent by way of a volunteer go-fer resulted in me being the proud owner of 6 quarts of Tornado Red. (I was able to return the extra gallon of clearcoat and hardener). The Fox/lab rat/guinea pig is about the size of a Pinto. Might have to paint a few more vehicles around here a bright red.

data for the basecoat (PDF)
data for the clearcoat (PDF)
 
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#53 ·
So I should have guide coated the epoxy? I had it in my head that the guide coat came between 2k p/s and basecoat. That presumes only very minor fill is needed, though, like a skim coat. Maybe a guide coat on the epoxy would make up for bad eyes. :)

1. Sand or blast to prep for epoxy
2. 2 wet coats epoxy
3. guide coat
4. filler work
5. repeat 3, 4 if needed, then seal with epoxy
6. 2k p/s or 2k sealer (scuff epoxy if past the time given by manufacturer)
7. block for basecoat
8. basecoat
9. clearcoat

Does that look right?
 
#54 ·
That looks good, you would use a seal coat before topcoating with a metallic. For us a sanding sealer would be best. You can guide coat any time. I sometimes guide coat bondo when feeling lost. There's people on this forum who use epoxy for all the under coats including the sealer coat. My GTO is lacquer primer over metal prepped steel with lacquer top coat. There are many ways to get to the same result.
 
#55 ·
grouch said:
1. Sand or blast to prep for epoxy
2. 2 wet coats epoxy
3. guide coat
4. filler work
5. repeat 3, 4 if needed, then seal with epoxy
6. 2k p/s or 2k sealer (scuff epoxy if past the time given by manufacturer)
7. block for basecoat
8. basecoat
9. clearcoat

Does that look right?
Yes that proceedure will work fine, just remember the guidecoat needs to come off before anything also goes on. So if it shows a low area definately sand the remaining guidecoat off of that area before applying any fillers.
I guidecoat religiously in all the work I do. Also when stepping down on sanding grits I'll apply guidecoat between sandings-this shows you when enough material has been removed. Example: On polyester primers I'll often start with 120 and cut till straight, then apply more guidecoat and go over it again with 180 till perfect, then more guidecoat and step down to 320. The guidecoat lets you see the imperfections your sense of feel will never find.

Spray bomb guidecoats are handy but they add up $ fast, same with powdered guidecoat ($30). I buy gallon cans of black elcheapo $30 lacquer primer and reduce it 200% giving me 3 gallons of sprayable for appox $40. This gets loaded in an old JGA502 siphon feed gun and stays there ready to use at will. I can dial the gun from a 1" pattern to 8" to handle whatever part I'm working on. You can usualy find lacquer primer in black, grey, and red to work over whatever colored surfacer you're using. Do the math and your money ahead, very convenient, and less garbage to toss (spray cans).
 

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#57 ·
Sorry. I haven't updated because there haven't been any significant accomplishments. I'm still putting stuff on and sanding it back off, when I have time.

At least I'm consistent in my screw-ups -- I put on 1 good coat and follow it with 2 lousy ones that have to be sanded back off. That happened with the 2k primer/surfacer just as it did with the epoxy. Right down the middle of the hood and the middle of the roof I had very rough streaks. I thought at first it was trash coming from the cowl vent, but then it happened on the roof, too. When I shot some thinner through the gun to clean it, it bubbled around the head where it's knurled. My guess is that this was enough to prevent enough atomization of the 2k p/s and, coupled with the high humidity, caused it to shoot gray BBs. Apparently I let the gun get farther from the surface as I spray the center of the hood and roof because those were the worst.

I had to sand and glaze the hood and roof after that. The hood was a surprise. After sanding it with 400, I could see that it was concave on each of the triangular wings along each side of the hood. The main part had a bump on each side that looked like collar bones sticking throug a tee shirt. It's flat now but multi-colored.

The roof is also multi-colored but not yet flat. When I get it sanded, I'll spray those two panels with 2k p/s again and start wetsanding to 600, again.

Whoever came up with body filler and glazing is or was a sadistic, evil genius. It's just diabolically bad chemistry to have mix ratios measured in "ribbons" and "puddles". Oops, the temperature went up 1 degree, you should have shortened that ribbon a fidget! There has to be something better than plasticized talc.
 
#61 ·
update

It's a red VW now. It also has quite a bit of trash in it and I'll have to figure out how to deal with that before that 24 hour clock runs out -- tech sheet for the basecoat says 24 hours maximum to topcoat.

No pictures yet (just got out of my now-pinkish coveralls, gloves and air hood), but I'll post some as soon as I can stand the fumes long enough to snap a couple.

After reading some comments on here about trash and cowl vents, I made sure mine was clean. The trash came out of the little gap around the windshield, instead. I also overlooked some in the well around the trunk lid. Another source of roughness came from overspray on the top.

I found a very few pinholes in the 2k primer/surfacer just a couple of days ago and had to fill them with glazing. I didn't reshoot after sanding that. The gray Scotchbrite that baddbob suggested made a real difference in the appearance of that gray. After rubbing the whole thing down last night, I just decided it was going to be painted today. I wiped it down with wax and grease remover 4 times starting about noon, let it dry about 3 hours after the last wipe, then set up to spray basecoat.

It ain't perfect, but it doesn't appear to be a disaster either. It took 32 oz of basecoat for the first coat (plus 32 oz of reducer), mixed in 4 batches. The second coat didn't take quite as much, but I shot all that I mixed anyway. The color is surprisingly even for a first-timer. Maybe I'll get lucky with the clear.

A note about that Shopline JP202 2k primer/surfacer: I wouldn't recommend it to a masochist. The stuff is inconsistent in color and more trouble than it's worth, IMO.
 
#62 ·
I'm glad your alive. I was begin to think an army of those self propelled cable cutters got to you. You can't scuff the dirt and clear it with out risking the red will look streaky. I would just clear it. Later just spot repair the parts that bug you the most. Next time try panel painting. It is amazing how the color coat attracts debris that the surfacer never will.
 
#63 ·
Thanks perrib. Not dead, just pinin' for the fjords, or something like that. Been pushing it for the last month or so -- working on house contruction by day and sanding that car by night.

perrib said:
You can't scuff the dirt and clear it with out risking the red will look streaky. I would just clear it.
I might have to trim some of the worst places down with an axe or machete just to have enough clearcoat to cover the whole thing. Well, it's not quite that bad, but I do wish I could shave the thing somehow. I'm anxious to see what the surface looks like because I was worried about every little mark I could see in the gray beforehand. It says each coat provides 0.5 mil of build. That's not very thick and doesn't sound like it could hide much.
 
#64 ·
photos

I made a quick dash into the 'booth' to snap a couple of pictures. Didn't fire up the fresh air so my eyes were burning too much from the fumes to stay to take more photos.

Those white dots on the red hood and fender are bits of styrofoam!

Also attached: 1 from 10 days ago showing the mottled hood and top, and 1 today showing what it looked like just before spraying.
 

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#66 ·
I'm not sure about the coverage yet. It looked like the 2nd coat covered everything, but I was looking at it through a plastic tear-off coated with overspray. Things might be different when seen without that rosey tint. :D

I know where there were some yellow spots showing through the gray, so when I can get back in there I can try to find those again. If I can tell where they are, I'll shoot it again.

Could that overspray dust that's everywhere indicate that I've got the pressure too high to the gun or is it normal in a makeshift booth?
 
#67 ·
Two coats with red might not be enough. Take a better look today when the fumes are cleared out. If you can roll it outside, better yet. Other then that, it looks good and 2-3 coats of clear will bring out the shine. Then - GOOD NEWS - you get to bring out the wet 'n' dry again :sweat: :D for some more fun.

I did my roadster with DuPont BC - a yellow/orange - and over the recommended light gray color primer, and I had to put down 2-3 more coats beyond the 2 recommended as it shadowed thru

Dave W
 
#68 ·
Hiding was complete -- the coat is even, without changes in color except for that infernal stripe down the middle of the top that has plagued me with everything sprayed since the start. All the commentary about coverage has me suspicious that I've been spraying a lot heavier than I should.

There were sharp bumps over every horizontal surface. The doors, fenders and tail are slick. My guess is that I made more of an overspray problem than a trash problem. I used some dry 600 grit paper to knock off the worst bumps on the hood and top (resisting a very strong urge to "sand it FLAT", due to results of tests posted by martinsr and baddbob last year). Blew off the dust, wiped it with a paper towel that had been very lightly misted with Endust (forget who posted that and when), and shot a thin coat of base over every panel where I de-nibbed it. (These bumps were big enough and sharp enough to call 'em nubbins instead of nibs).

I'll shoot clear in about an hour. It's a long way from 'good', but any flaw in it now is going to be permanent, or at least as permanent as the paint.
 
#69 · (Edited)
update -- clearcoat

A quick update -- I just shot 2 coats of clear. Lots of orange peel, maybe lots of trash. 72 oz of JB620 clear and corresponding JB6285 hardener (4:1). No stripes this time, I think.

Gotta go tape a high school football game. Will post photos of the car ASAP.

[Edited to add:]

I was wrong. It is a disaster. At this point I really wish I had simply shot some tractor and implement enamel. It's less toxic, less of a mess, less finicky, less expensive and I've never, ever had orange peel in it to compare with this bc/cc mess. All that work to get things smooth and straight -- wasted. A roller and latex house paint would produce a smoother topcoat. Hmm. Maybe a belt sander and a bucket of house paint poured over it while it's still masked...

First shots show the worst of the basecoat, before clear. The rest show the hideous clearcoat.
 

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#70 ·
salvage

The initial shock and disgust have faded and I've started salvage operations. Part of the night was spent wetsanding with 360 and quite a few hours were spent reading.

It looks like gun setup -- lack of atomization -- caused the orange peel look. Unless I've missed something in my research, I should be able to shoot more clear on this without creating a future delamination problem, so long as I don't sand through to the basecoat. Since it's a very rough surface, I'm using 360 instead of a finer grit, because I want to get the tops of those hills cut off before next year.

Photos of the current state of the car are attached. In one of the threads I read, the phrase "Stucco under glass" was used to describe new car paint jobs. Mine could be called "Stucco after ice storm" or "frosted cinder block".
 

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#71 ·
All I can say is OUCH.

You are correct - it is improper atomization. Just a quick question or three - what kind (brand) of gun are you using? What pressure setting? What distance are you shooting at and what stroke speed?

My HF 'purple' did some of that heavy peel with primers when I first started and used their suggested settings. I finally ended up at 45+psig at the gun. I sold the gun and decided to start using my Devillbiss FL3 for primers and bought an Iwata for BC/CC. I hadn't painted since spring but had to redo my steering column on Friday - and I had very little peel and was able to cut and buff/polish by hand in about 10 minutes - and I for sure am an amateur, with the last car I painted was at least 15 years ago.

What you are doing is about all possible - and there are probably going to be sand throughs - panel painting sometimes helps reduce the frustration - screw up one panel - easy to fix. These pieces are the way I painted my car - and yes, I did redo the frame horn covers (too thin) and the column (scratched) as well as both of the car's rear quarters (solvent pop, thin cover). My paint - ~$650/gallon + activator @ ~$100/gallon :pain:





Finish your sanding with 400-600 wet, maybe mist on another coat of red, then 2-4 coats of clear and you should be in good shape.

Dave W
 
#72 ·
Irelands child said:
All I can say is OUCH.
Yeah, it's a pain. Earlier you said, "Then - GOOD NEWS - you get to bring out the wet 'n' dry again for some more fun." Bet you didn't imagine then how much ~fun~ was on the way.

Irelands child said:
You are correct - it is improper atomization. Just a quick question or three - what kind (brand) of gun are you using? What pressure setting? What distance are you shooting at and what stroke speed?
It's the Harbor Freight purple gun -- 43430. Pressure was somewhere around 30 psi at the gun, but something crazed the faceplate of the gauge and I can't read it any more. Should've checked it with another gauge before shooting. I'm kinda slow on spraying, moving about 1 foot per second or a fudge less, I think, while staying 6 to 8 inches from the surface. I'm still not robotic about it and tend to have an inconsistent speed or distance or even tilt, especially doing the top.

Irelands child said:
My HF 'purple' did some of that heavy peel with primers when I first started and used their suggested settings. I finally ended up at 45+psig at the gun. [...]
I'm going to test with a higher pressure, too. Things that seem to me to indicate that pressure is my problem:
1. Spots where there were overlaps in quick succession (much less than the 5 minute flash time) turned out from good to glassy.
2. Horizontal surfaces are much rougher than vertical, which suggests that gravity helped overcome surface tension on drops that were too large. (Take a surface that beads water, mist it while horizontal and the drops just stay there; mist it while vertical and at least some will run together).
3. There are a lot more bumps on horizontal surfaces than on vertical. When I first looked at it without fumes burning my eyes, I thought it had small fisheyes all over. Instead, it looks like glops of clear that shrank, leaving a fairly neat circle of clear around each. The depth of that circle or crater appears to be no greater than the depth of the valleys in the orange peel. On the sides, the bumps don't have the crater; they only appear around those on horizontal surfaces. Again, gravity pulling those globs sideways would smear them flatter on vertical surfaces.
4. The fluid control was set at 1 1/2 turns out, which sprayed the epoxy just fine and even worked fairly well for the 2k primer/surfacer (I ended up at 2 turns out before getting the 2k p/s spraying smoothly enough).

Irelands child said:
What you are doing is about all possible - and there are probably going to be sand throughs - panel painting sometimes helps reduce the frustration - screw up one panel - easy to fix.
I have plenty of basecoat left if I have to take any panel down to primer again.

Irelands child said:
These pieces are the way I painted my car - and yes, I did redo the frame horn covers (too thin) and the column (scratched) as well as both of the car's rear quarters (solvent pop, thin cover). My paint - ~$650/gallon + activator @ ~$100/gallon
That makes my screwup cheap by comparison! BTW, your booth is too neat and your panels too glossy. At least your airhose gets tangled. :/

Somehow I had it in my mind that you used Tyvek for your booth. I'm going to try making up panels with conduit and Tyvek for a take-apart booth next time. This polyethylene just lets go of giant flakes with really bad timing.
 
#73 ·
Grouch, I hope the next round of clear flows as smooth as glass. It should flow better and if your atomization gets figured out I bet you'll do just fine. For plastic sheeting you could use regular plastic masking, it comes on a roll available at most paint supply places for like $35 and will provide enough plastic for 5-6 temporary booths like yours, and the overspray sticks.
 
#75 ·
grouch said:
Yeah, it's a pain. Earlier you said, "Then - GOOD NEWS - you get to bring out the wet 'n' dry again for some more fun." Bet you didn't imagine then how much ~fun~ was on the way.

.....it's called a very steep learning curve :p :pain: :thumbup:



It's the Harbor Freight purple gun -- 43430. Pressure was somewhere around 30 psi at the gun, but something crazed the faceplate of the gauge and I can't read it any more. Should've checked it with another gauge before shooting. I'm kinda slow on spraying, moving about 1 foot per second or a fudge less, I think, while staying 6 to 8 inches from the surface. I'm still not robotic about it and tend to have an inconsistent speed or distance or even tilt, especially doing the top.

It looks like you are moving much too slowly with an HVLP spray gun. Consistency and speed are my downfall as well

I'm going to test with a higher pressure, too. Things that seem to me to indicate that pressure is my problem:
1. Spots where there were overlaps in quick succession (much less than the 5 minute flash time) turned out from good to glassy.
2. Horizontal surfaces are much rougher than vertical, which suggests that gravity helped overcome surface tension on drops that were too large. (Take a surface that beads water, mist it while horizontal and the drops just stay there; mist it while vertical and at least some will run together).
3. There are a lot more bumps on horizontal surfaces than on vertical. When I first looked at it without fumes burning my eyes, I thought it had small fisheyes all over. Instead, it looks like glops of clear that shrank, leaving a fairly neat circle of clear around each. The depth of that circle or crater appears to be no greater than the depth of the valleys in the orange peel. On the sides, the bumps don't have the crater; they only appear around those on horizontal surfaces. Again, gravity pulling those globs sideways would smear them flatter on vertical surfaces.
4. The fluid control was set at 1 1/2 turns out, which sprayed the epoxy just fine and even worked fairly well for the 2k primer/surfacer (I ended up at 2 turns out before getting the 2k p/s spraying smoothly enough).

Fluid settings should normally be +/- 2 to 2 3/4 turns out with a full fan opening, depending on that particular gun. Quite frankly, I'd try to find an inexpensive Astro spray gun (~$70) and relegate that HF gun to primer use. I didn't get my Iwata out for the steering column and just used my Devil FL3 - and it worked fine - and for me has proven to be a pretty good low end gun



I have plenty of basecoat left if I have to take any panel down to primer again.

You'll probably need most of it :D

That makes my screwup cheap by comparison! BTW, your booth is too neat and your panels too glossy. At least your airhose gets tangled. :/

You should see it when I have my white supplied air respirator hose wrapped up with that yellow/orange hose - then wrapped around my legs

Somehow I had it in my mind that you used Tyvek for your booth. I'm going to try making up panels with conduit and Tyvek for a take-apart booth next time. This polyethylene just lets go of giant flakes with really bad timing.
What I use for the booth side is .003mil 10x20 lengths of plastic sheeting. The top is held to the ceiling with 1x3 furring and the bottom wrapped around 2x4 studs and stapled in place. Three of the corners are taped or stapled to wood, the 4th is my "door and big paper clamps hold that together. The fan is a 1050cfm explosion proof variable speed greenhouse unit that clears the booth continuously set at about 2/3s speed.

Remember - I'm a bottom level amateur with these exotic new paints and HVLP guns - these guys here (and on the SPI forum) like baddbob and several others coached me through my project. Am I 100% happy? - no, but probably 85% as I too have some residual 'peel, but will work most of that out over time.

Keep us updated
Good luck,
Dave W
 
#76 ·
progress report

Before the update... I can't tell you folks just how much I appreciate the encouragement, assistance, and the persistence you've shown in providing both throughout this. It's really made a difference. Thank you!

Some progress pictures are attached. (Didn't work on it at all yesterday).

The hood is turning out better than I'd hoped. I think it's about time to switch from 360 to 600 on it. It and the cowl still have some tiny glitter spots, but I'm not certain of the thickness left, so I'll shoot over those.

(Is there some practical way to figure out how much clear is left, or do you just go by nerves and past pain?)

The passenger's side front fender needs more work -- I've just started on it. The side lips of the hood won't get any more than what's seen in the 03 photo -- I cut through those things at the front and along the raw, thin lower edge when sanding the epoxy and primer/surfacer, so I know it's real easy to do. I saw some pink on my sandpaper on the last stroke on the hood lip on the driver's side, so there's a cut-through there somewhere. Guess I'll see how long that survives under new clear.

The top and the trunk lid need more 360 sanding. (I wonder if the idea of metal flake came from some poor soul trying to sand out orange peel and noticing the glitter).

I haven't started on the sides, except the passenger's front fender, but they are not nearly as bad as the horizontal surfaces. That one front fender is the worst and was only really bad along the top edge.
 

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