What would you do with this mess

[Charles]

Although I'm embarrassed to post this pic, since I did everything wrong, it seems, I need help! :0
Meanwhile I know I'm in for a lot of sanding. But can any of this mess be saved? It's a catalyzed (2-part) urethane from POR15 called "Hardnose" or "Whitecote".

I'm saving up for a decent spray gun which was part of the problem, I could see the atomization was not good but plowed ahead anyway... There are runs in multiple places, heavy orange peel, and worst of all, little holes (fisheyes?) right through to the primer, mostly on the left front fender and the roof. They are not as visible in this door pic but you can see the other problems all right. Did I not get the surface clean enough?

I was prepared to sand the runs and orange peel, then re-coat, but I don't know what to do about the pinholes. Can I use glazing putty to fill them, or do I need to sand right down to the primer and start over with the paint?

thanks
Charles

[Len]

Although I'm embarrassed to post this pic, since I did everything wrong, it seems, I need help! :0
Meanwhile I know I'm in for a lot of sanding. But can any of this mess be saved? It's a catalyzed (2-part) urethane from POR15 called "Hardnose" or "Whitecote".

I'm saving up for a decent spray gun which was part of the problem, I could see the atomization was not good but plowed ahead anyway... There are runs in multiple places, heavy orange peel, and worst of all, little holes (fisheyes?) right through to the primer, mostly on the left front fender and the roof. They are not as visible in this door pic but you can see the other problems all right. Did I not get the surface clean enough?

I was prepared to sand the runs and orange peel, then re-coat, but I don't know what to do about the pinholes. Can I use glazing putty to fill them, or do I need to sand right down to the primer and start over with the paint?

thanks
Charles

That's pretty rough. I would probably take some 320 wet sandpaper on a block and sand it down until smooth then, if it's still not smooth enough, I would probably coat it with some filler primer, guide coat and block sand with some 400 before repainting. Don't use the POR15 again, get some real car paint from a brand name source like PPG, DuPont, BASF, Sherwin Williams etc. Use a decent spray gun and WAIT between coats until the paint flashes before applying your next coat. Too much, too fast can create a lot of problems.

[Bob K]

First let me answer a question you didn’t ask. I would never put any POR 15 product in a good gun. You saved yourself some heart ache by not having an expensive gun yet. That stuff sets up fast like concrete and getting it out of your gun in time might be impossible. Once it sets up you need to use tools that can damage the fine machining of the tip and air cap.

As far as what you have that may be as good as it gets. Isn’t that product made for frames and hidden parts that get abraded by sand and water mix? At this point I would treat it as if it were filler and sand it flat with 180 grit and put a more conventional paint on the door.

That’s just my opinion. I don’t use POR 15 any more. I used one pint once and that was a lifetime supply of doing that for me, never again.

Bob K

[style]

Although I'm embarrassed to post this pic, since I did everything wrong, it seems, I need help! :0
Meanwhile I know I'm in for a lot of sanding. But can any of this mess be saved? It's a catalyzed (2-part) urethane from POR15 called "Hardnose" or "Whitecote".

I'm saving up for a decent spray gun which was part of the problem, I could see the atomization was not good but plowed ahead anyway... There are runs in multiple places, heavy orange peel, and worst of all, little holes (fisheyes?) right through to the primer, mostly on the left front fender and the roof. They are not as visible in this door pic but you can see the other problems all right. Did I not get the surface clean enough?

I was prepared to sand the runs and orange peel, then re-coat, but I don't know what to do about the pinholes. Can I use glazing putty to fill them, or do I need to sand right down to the primer and start over with the paint?

thanks
Charles

why did you use por 15,just curious..sand it with 80 grit then use a decent 2k primer decent meaning stay away from nason and omni products..

i bought some nason 2k primer cause i ran out of finish one and everyone closed in 10mins i just tried sanding some nason and used 26 sheets of 400grit on a hood an 2 doors took 3 hours...on a good note i just bought a 900k volt stun gun and cant wait for the dupont rep to show his face around here again..STAY AWAY FROM NASON!!

[Charles]

Thanks for your input, everyone. This is not their POR-15 Rust Preventive Paint you're probably thinking of, about which I too have mixed feelings. I wouldn't paint a car with POR-15, anyhow, it is as the name implies for rusty metal areas (POR = Paint Over Rust).

This (http://www.por15.com/HARDNOSE-PAINT/productinfo/HNGB/) is the stuff I sprayed. Although it has their company name on it, it's a pretty "standard" acrylic urethane with isocyanate hardener. One reason I wanted a very tough paint is that I live 2 miles off the paved county highway and dirt/gravel roads are hard on car paint!

Also they claim it can be applied by brush, roller or spray and will flow out and not leave marks even if applied by a brush. I didn't care to try that but maybe it'd have come out better :?

Pot life is said to be 8 hrs if it's kept sealed, and 1 hr to touch dry once sprayed, with 4+ days for complete cure. I didn't have any trouble cleaning the gun with lacquer thinner (but I'm probably going to throw that gun away anyway) :D

[Charles]

That's pretty rough. I would probably take some 320 wet sandpaper on a block and sand it down until smooth then, if it's still not smooth enough, I would probably coat it with some filler primer, guide coat and block sand with some 400 before repainting.

Thanks, I was afraid I'd have to take it down to bare metal and start from scratch!
I'll try it once it cures (colder weather is starting tomorrow so it may be a couple of weeks before it's fully cured).

Can I not use a DA air sander, at least initially? Sanding the whole car that much by hand is going to take quite a while...

[Len]

Thanks, I was afraid I'd have to take it down to bare metal and start from scratch!
I'll try it once it cures (colder weather is starting tomorrow so it may be a couple of weeks before it's fully cured).

Can I not use a DA air sander, at least initially? Sanding the whole car that much by hand is going to take quite a while...

You can use a DA but it's probably going to load up the paper pretty quick if the paint isn't fully cured. Usually the problem with a DA is that it won't result in a flat/level surface so the priming becomes even more important. No matter how you sand it I'd recommend using a decent "guide coat" so that you can see what you're doing as you're doing it. A light dusting of guide coat won't interfere with the sanding and it shows the low spots so that you can sand down the highs to meet them.


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[Charles]

I'm a bit confused...

I was going to wait until the paint is fully cured before trying any kind of sanding, exactly because it would just load up the paper with a gummy mess.

Re: your initial suggestion of wet sanding with 320 grit and seeing if it's smooth enough; what I had in mind was using the DA mostly on the big runs, and then finishing with a block to get it more level.

Did you mean that I should expect to re-prime anyway?

thanks for your patience.

[Bob K]

I think you should rethink your sanding strategy. I would try to sand it right away as a test. Try various grits and try wet as well as dry. It would be a shame to loose the ability to sand it while fresh only to find that it gets worse with age. If it gums up the paper now then you can wait a week for it to get harder, but what if sooner is better and you don’t try?

I hope you don’t plan to use the same product again. I say that because you stated earlier that you felt it might have gone better with a brush. I don’t think so. The brush marks may disappear but the surface quality won’t be any better.

You said “it’s a pretty “standard” acrylic urethane with an isocyanate hardener.” Where did you get that information? From what I read it is a moisture cured urethane that is designed to be applied to chassis parts (frame) and floor pans when used in an automotive setting. It is two part, I’ll give you that but I couldn’t find the MSDS to see about the isocyanate hardener. I don’t think they meant for it to be applied to the outer surface of a car.

I’m trying to say this without being unkind, but you didn’t say how old the car is or how valuable it is so did you consider just leaving it alone and go with the custom textured look? Maybe spraying a coat of a contrasting color and then lightly sanding the top off the high spots to get a random pattern? Just something to think about. Evaluate where you are with this and try to make the best of it without making a career out of fixing it. If it is a 2009 Lexus then fix it right but if it’s a 1995 Taurus well maybe something off beat may actually spice it up a little. Good luck and try to make it fun no mater what you decide to do.

[Charles]

Appreciate the help. OK, I'll go try sanding a piece of it today and see what happens.

No, I'm not planning to try it again (although I suspect the fault lies with my improper application, not the product). "High gloss, extreme durability topcoat" for, among other things, "general automotive use" certainly sounded to me like I can paint a car with it...
http://www.por15.com/Data%20Sheets/hn_wc%20directions.pdf

I'm no paint expert so I may have misused the terms. It is moisture cured. I don't see the MSDS on the website either; however I did read the can labels and it's definitely a 2-part urethane with an HDI catalyst (mandatory hardener).

The car is a '72 Dart that is getting a 500+ hp big-block and 4-speed transplant. Some people rave about "patina" and "rat rods" but I just want a decent paint job, not trying for a concours winner!

[Mooch]

It is a good product for painting frames , tractors and anything that gets exposed to the weather .

It isn't a product to use as a finish coat on a car . Thought it would be hard to beat as a finish on a woods truck or jeep .

I would sand it as that stuff gets pretty hard .

mooch

[Charles]

Going out to experiment with some sanding now.

I'm not trying to be difficult, but can you please explain WHY it is not a good finish coat for a car (vs. an off-road vehicle)? Certainly it will be frequently exposed to the weather, just like my tractor, and driven on gravel/dirt roads :D

Can't it be sanded/buffed to a smooth finish at least as good as factory appearance?

[Mooch]

Going out to experiment with some sanding now.

I'm not trying to be difficult, but can you please explain WHY it is not a good finish coat for a car (vs. an off-road vehicle)? Certainly it will be frequently exposed to the weather, just like my tractor, and driven on gravel/dirt roads :D

Can't it be sanded/buffed to a smooth finish at least as good as factory appearance?

After reading the tech sheets on it .. maybe you should wait .


Remember, thinning rates are a guide only. Consider also
the type of gun, air temperature, and humidity. Hardnose /
Whitecote can be cut with regular compounds if you have
a run or imperfections, though it is best if you leave it for
a week or two before cutting to make sure coating is hard
(runs may take longer to fully cure due to added thickness

Mooch

[Charles]

I just spent an hour and a half wet-sanding with 220 grit paper on an 8" sanding board (if that's the right term, a hard plastic surface with a handle, and 1/4" rubber foam pad between that and the paper). I concentrated my efforts on the curtain runs, but made a light pass over the entire surface. The paint sanded quite readily but does not gum up the paper or lift. Rinsing with water didn't hurt it either. It's been 48 hrs since I sprayed, but it's been warm and it looks like this was the right time to attack ;)

The worst couple of runs will need a razor blade or nib file, but the job is actually looking salvageable at this point :)

The orange peel is already diminished even in the areas I only hit once or twice.
Do I need to have all the orange peel gone before putting more paint on?

Also, what do I do about the numerous pinholes in some places... will the second coat fill them, or do I use glazing, or (worst-case) have to shoot primer and sand again?

thanks!
-Charles

[Bob K]

Glad to hear it’s looking better. As for sanding out all the orange peal that would be the best case solution since the new paint won’t grab as well on shiny paint left in the low spots and any orange peal you leave will be magnified in you next coat. The pin holes will show up. I can’t remember ever hiding any of them by painting over them. I have on the other hand been surprised by a pin hole showing up in my paint where I hadn’t noticed it in the filler. It would be best to sand them all the way out. Pinholes are hard to fill because air gets trapped in them and pushes any filler out and prevents anything getting into the bottom of them. You may be satisfied with leaving some of the orange peal. Leaving the orange peal is a judgment call on your part. It all depends on how nice you want it to look verses how much effort you are willing to put into the prep.

Bob K

[Charles]

Here are a couple of pictures of the worst pinholes. The runs are still looking bad in the first shot because I didn't do much sanding here (noticed a big dent nearby I'd somehow overlooked when it was in primer, so will need to work on that). Also the "rings" are artifact of the digital camera and closeup flash.

I did some searching on this board and some feel that they can be filled with paint or putty but it probably is simpler to sand them out.

Since I'm going to (eventually) spray another coat of a 2-part urethane, should I keep using 220 grit or final-sand with 400?

[Len]

Here are a couple of pictures of the worst pinholes. The runs are still looking bad in the first shot because I didn't do much sanding here (noticed a big dent nearby I'd somehow overlooked when it was in primer, so will need to work on that). Also the "rings" are artifact of the digital camera and closeup flash.

I did some searching on this board and some feel that they can be filled with paint or putty but it probably is simpler to sand them out.

Since I'm going to (eventually) spray another coat of a 2-part urethane, should I keep using 220 grit or final-sand with 400?

You could probably get away with 220 dry sanding if you're going to keep it white and polish it when you're finished but it would be best to wet sand it with some 400 to help eliminate one of the variables that could come back to haunt you later.

[Charles]

Actually I've been wet-sanding with the 220... ok, when it looks smooth I'll do a bit of wet 400 as long as the next coat will properly adhere.

What variable are you referring to?
thanks.

[Len]

Actually I've been wet-sanding with the 220... ok, when it looks smooth I'll do a bit of wet 400 as long as the next coat will properly adhere.

What variable are you referring to?
thanks.

If you're painting with a decent urethane and sanding with 400 or 800 or 1200 or even finer sandpaper is enough scratch for the paint to bond to the surface. The big variable in using a coarse scratch like 220 is that the paint could take a long time to fully cure and it could shrink into the sand scratches over time causing the job to dull. If you use a "good" paint and prep it properly you should be fine.

[Charles]

OK. Today I spent another three hours wet-sanding the runs off with 220, and most of the orange peel is gone too. It may actually look decent some day 8)

But the pinholes are still there, because they go right down to the primer, so I can't sand them out without removing all the paint over large sections of the body... at least they are not volcano craters any more though.

So what's the simplest way to fill them? Glazing putty, spray primer, or perhaps roll-on primer?

thanks.
-Charles

[Len]

OK. Today I spent another three hours wet-sanding the runs off with 220, and most of the orange peel is gone too. It may actually look decent some day 8)

But the pinholes are still there, because they go right down to the primer, so I can't sand them out without removing all the paint over large sections of the body... at least they are not volcano craters any more though.

So what's the simplest way to fill them? Glazing putty, spray primer, or perhaps roll-on primer?

thanks.
-Charles

I would probably mix up a little filler primer and drop it into each crater or I'd coat the entire area with a light coat of putty if there were a lot of craters.

[tr6oldtimer]

I sprayed a clear urethane and have pin holes here and there. Fortunately I could sand them out, but what is the cause? The other panels I have painted did not have this problem. The only difference is those panels were painted with a conventional gun, and on the last ones I used an HVLP gun I acquired awhile back.

Am I putting the paint down to heavy, not enough air, improper reducer, not enough, water, or what?

Pin holes suck.

[Len]

I sprayed a clear urethane and have pin holes here and there. Fortunately I could sand them out, but what is the cause? The other panels I have painted did not have this problem. The only difference is those panels were painted with a conventional gun, and on the last ones I used an HVLP gun I acquired awhile back.

Am I putting the paint down to heavy, not enough air, improper reducer, not enough, water, or what?

Pin holes suck.

Pin holes in new paint is usually "solvent pop" which is caused by either applying too much too fast or by putting the newly painted surface in the sun before the solvent has escaped. After you apply your first coat be sure to allow it to dry to the touch before applying your second and third coats. The newer compliant guns like the Plus, Tekna or the Sagola 4400 will atomize so finely that the coating is very thin and smooth and less likely to cause solvent pop.

[tr6oldtimer]

Thanks Len, it appears I had had applied too heavy a first coat, then applied the the second coat before the first had set. I also recall I was spraying in an 85 degree environment.

I will proceed with more lighter coats then fewer heavy ones.

[Charles]

On close inspection, my pinholes also appear to be from the paint going on too heavy (the crappy gun was depositing much more paint on part of the pattern, and with poor atomization). Didn't get a chance to try the glazing putty today but it's supposed to be 71F tomorrow ;)

[Len]

On close inspection, my pinholes also appear to be from the paint going on too heavy (the crappy gun was depositing much more paint on part of the pattern, and with poor atomization). Didn't get a chance to try the glazing putty today but it's supposed to be 71F tomorrow ;)

Yes, that's the problem with guns that don't atomize well, the coating goes on much heavier.

[Charles]

Today I learned about "Professional Finishing Glaze"... it hardens VERY fast, so only mix small amounts at a time! A piece the size of my little finger was about all I could spread before it hardened too much to smooth with the plastic spreaders.

My car now looks like an adolescent covering his acne with Clearasil... but the pinholes are filled . :) There is still too much orange peel, so this was a good time to use the glaze before continuing to sand the entire body.

Since the directions said, "may be sanded in 30 minutes" I tried it after an hour, with 220 (dry). The paper clogs really fast. Can this stuff be wet-sanded?

[Len]

Today I learned about "Professional Finishing Glaze"... it hardens VERY fast, so only mix small amounts at a time! A piece the size of my little finger was about all I could spread before it hardened too much to smooth with the plastic spreaders.

My car now looks like an adolescent covering his acne with Clearasil... but the pinholes are filled . :) There is still too much orange peel, so this was a good time to use the glaze before continuing to sand the entire body.

Since the directions said, "may be sanded in 30 minutes" I tried it after an hour, with 220 (dry). The paper clogs really fast. Can this stuff be wet-sanded?

This is one of the reasons I use Quantum 1, the hardening time can be extended using the slow hardener and large areas can easily be covered smoothly.


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[Charles]

Thanks, I will use that filler next time ;)

Meanwhile, there seems to be considerable disagreement on the subject of wet-sanding body filler (as it is not waterproof and can cause rusting beneath it). The glazing I used does not go down to bare metal though - the pinholes are in the paint I applied, not the intact primer.

So, any thoughts on wet-sanding?

[Len]

Thanks, I will use that filler next time ;)

Meanwhile, there seems to be considerable disagreement on the subject of wet-sanding body filler (as it is not waterproof and can cause rusting beneath it). The glazing I used does not go down to bare metal though - the pinholes are in the paint I applied, not the intact primer.

So, any thoughts on wet-sanding?

I don't like wet sanding body filler because it's like a sponge and the moisture can effect it's bond with the surface. I'd recommend that you use some 120 dry sandpaper to remove most of it then go to a finer grit dry sandpaper before priming and painting. You can try wet sanding the filler but it's a risk that may come back to haunt you later.

[Charles]

Got a roll of 3M adhesive-backed sandpaper. It works surprisingly well and does not clog fast when dry-sanding. I sanded all the glazing spots and some more of the orange peel.
There is one spot on the hood (along a raised edge) that had a small rust bubble and I have clean bare metal exposed now, about the size of my little finger... since I won't be painting until spring, what should I apply over it? Rattle-can primer?

[Len]

Got a roll of 3M adhesive-backed sandpaper. It works surprisingly well and does not clog fast when dry-sanding. I sanded all the glazing spots and some more of the orange peel.
There is one spot on the hood (along a raised edge) that had a small rust bubble and I have clean bare metal exposed now, about the size of my little finger... since I won't be painting until spring, what should I apply over it? Rattle-can primer?

Yes, you can use rattle can primer but be sure to allow it to dry a little between coats and put on 3 or 4 coats.

Next time you use sandpaper you should check out our Indasa paper it works great for less money. This paper works great on the Dura Blocks because it can be cut to any length and stuck on any of the blocks. It's also has a backing that can be peeled off to expose the adhesive or left on if you use a small piece by hand.


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