I've begun painting my car, panel-by-panel, starting with the trunk lid.
I'm using Interlux Bridghtsides paint. Yes, I'm rolling it on, mostly because I don't have a large compressor and because I am hoping to avoid all the mess of spraying in my garage.

I spent a few days patching holes (luggage rack once upon a time I think), and spent a few days putting on a few coats of primer. Sanding the primer was no problem, and I've now started with the color. Problem is, when I try to sand the paint, it sticks to the paper. There's no dust created, the paper just gets clogged right away. It's as if the paint's not dry. The can says leave it at least 16 hours, I've left it 28, and it's not cold in California.

Anyone know what's going on?

--Steve

Here's before primer
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After Primer
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Sanding Block after trying to color sand
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Are you supposed to use a hardener? I don't think it is intended to be rolled on either. Tough to follow the mixing instructions when you roll it on...

There's no hardener with this stuff, it's one part. It's also meant to be brushed on, which is why I'm trying it. In fact, the thinner I'm using, Interlux's recommended one, is called "brushing thinner." I used about a 10% thinner to paint mix, per the instructions. It layed down nicely too. Not really any brush/roller marks. But that was it for the good news.

are you wet sanding?

From what I read after a google search, it should be sandable.
Either the amount of thinner you used increased the curing time or the topcoat reacted with the primer preventing it from curing. Wait another day and see how it goes.
BTW, why would you use a marine (deck and trim) brushable single part polyurethane finish on your Porsche? Automotive paints incorporate a hardener for durability.
Would you do the same on either of the other cars in your picture? Even a bottom-of-the-line Maaco paint job would be much smarter IMO.

I used this paint quite a few years ago, but on a boat (fiberglass). I'm thinking either the paint needs longer to cure on steel, or you may be sanding too hard?

For boat application, I used a foam roller and an almost dry, high quality badger hair brush to smooth out behind the roller. Ended up with a pretty good "10 foot job" (which is about as close as most people get to look at a boat) - I'd want something better on a car, though.

Boat paint is formulated with an elastic property that exceeds automotive paint. This is because water and conditions of water wear on it like crazy. Salt water, junk in the water, and hot cold reactions from the sun with instant cooling from water splashing on the hot paint cause expansion and contraction. Paint cracking and delamination are improved with a flexible finish with good crosslinking from the poly. You CAN wet sand and buff it. But it takes alot more time and effort. The finish stays rubbery and will gum up the paper like old acrylic enamel without hardner. The process requires a ton of patience and lots and lots of sand paper.

BTW: You will notice the finish will chalk and require buffing every year. I'm not sure but some marine paints have anti-fouling properties and shed by chalking. Helps keep junk from collecting on it. Some boat guy will know more than me about that and may call B.S.

If I were you I would leave that paint at the shipyard and get some automotive top coat with a hardner. Even the lowest cost finish will give you a better end result.

Yep, many boat paints are ablative meaning they wear to keep barnacles and other nasty things from sticking. I know most ablative paint is super expensive (actually, its about as much as good catalyzed automotive paint) so this probably isn't a true ablative.

I too would personally go with an automotive paint, even if that means getting some Rustoleam and rolling it on like some guys on a Mopar forum did. It should provide a much better finish.

It's a car not a boat When you don't have the proper equipment it is usually best to pay someone who does to do the job. This is just another case that proves that point. I'm not trying to bust your balls here, I just don't get it when over and over people try to do these kind of things, they almost ALWAYS backfire, it is presented on the forums with an appeal for help, and yet again, someone else will try it.

Right now you have 2 choices. Let the car sit for a week and hope the paint sets up enough to wet sand and buff, or strip it all off and re-do it with AUTO PAINT. Even if you do not have the proper spray equipment, you could still use auto paint with a roller and at least have something that will harden properly and is made to be wet sanded and buffed. A gallon of Nason ful-thane single stage will set you back all of 150.00 and will yield more then enough paint to ROLL your car. Make certain you get the proper hardener for it

Rant over

I have seen marine paint professionally applied, on my boat, and it turned out beutiful, looked as if it was sprayed on. It is a true art
on the other hand, maybe becoming the future owners DAPO?

I'll 2nd Scotty on this. You are trying to sand and buff a paint that isn't really meant for that kind of finish. The paint lays down well when brushed or rolled because that's all you should do to it. It's always going to be rubbery, and gum up whatever abrasive you try and use.

cure time of teh primer is very important before you apply top coat, if you put some top coats on some uncured primers the top coat wont cure correctly. humidity and temp are also considerations. generally only laquers and catalized paints are wet sandable, most straight non-catalized enamels are not sandable (they dont get hard enough, at least for several months)

you MUST wet sand your paint, if you dry sand the paint builds up on the paper then teh paint is rubbing on paint, the paint stuck to the paper wont cut the paint on the panel, instead you get lots of friction and that makes heat the heat softens the paint and then you get more paint stuck to teh paper, and the situation gets worse.

when you wet sand you should never ever have paint stuck on the paper.

YOU MUST WET SAND!!!!! you MUST not press so hard as to not allow the water to wash away the residue. high sanding pressure can also soften the paint.

sand lightly and sand WET.


thickness of the paint might be a problem with curing. too thick and it may take weeks to fully harden.

i suggest you try some test panels with different thickness and dilutions of paint, then wait different times before WET sanding and se what works.

also remember the primer must be cured all the way, failure to let the primer cure al the way before top coat will result in top coat check marks as the primer shrinks months later. yes months later the check marks may appear if the primer was not fully cured before top coat, also top coat MUST be compatible with the primer. wrong choice and the top coat will soften the primer and cause problems with curing

try to wet sand now and see if that helps that may be your only probelm. light pressure use a blcok (never your hand, the flat block will prevent finger marks from being sanded into the paint)

You would have been better off with a Wagner power painter or a copy airless. At this point all the suggestions buy our paint guys are right. It does need to be wet. It looks like your paper is black so my guess is your using Wet Dry paper. Did you smooth out the primer or was that just rolled on?

You can use heat up your paint. You can get some cheep lights with stands from Harbor Freight or go to Home depot and get some with reflectors. You can get the old style outdoor big light to give you some heat. Just get the panel in an area with some cardboard boxes and let it get warm. I am in Los Angeles and my shop is not warm it is only 63 today.

Good luck,

Bob

Thanks for all the replies.

Why would I use a single part polyurethane marine finish on my car, and not an automotive finish? Because all the info I could collect indicated that if I were not going to spray, the Interlux boat finish was best. It wasn't cheap, in fact probably cost about as much as good automotive paint, but the word on the forums where people discuss roll-on paint jobs is that this is the best one. It's supposed to be the logical improvement from the Rustoleum so-called $50 paint jobs. Part of the supposed advantage over Rustoleum is that, ulinke Rustoleum, this polyurethane can be painted over without the need for fully stripping. I was not aware that it did not have the hardeners that automotive paints have, or that it in general did not have the same wearability, or that it would stay gummy. In fact, this is exactly the opposite of the experiences posted by dozens of anonymous users.

My point was not to save time. I expect this method would take significantly MORE time than spraying, particularly considering the extra wet-sanding that would be required to get a decent finish. I also didn't do it to save money, at least that was not an important part of it. I did it because spraying creates a mess. I doubt any of you guys with tons of experience but without a booth can argue otherwise. I've done enough of it to know the fumes WILL get from the garage to the house. I also would have to buy a compressor, and woudl be limited to 110v, which means I couldn't even buy the one I would really want (that would allow me to set up a media blaster as well).

Why not let a pro do it? Two reasons: 1) I'd have to fully strip and prep the whole car at once, which means way more time with the car out of commission - I prefer to work on things a bit at a time where possible; and 2) Whenever possible, I want to do it myself. It's the same reason I've never taken my 914 to a mechanic in the 14 years I've owned it. I enjoy driving a car that I keep running and I restore and I upgrade.

I didn't go into this haphazardly. I get why several of you replying think that, since you are of the firm (and it appears correct) opinion that my roller job will not work. I must have spent dozens of hours reading about the best way to go about this before starting, including reading every post I could find on this board about painting (including everything I could find written by Scotty B.).

So, that's a long-winded way of explaining how I got here. I tried sanding the trunk again today with pretty much the same, paint-is-too-soft, result. I may give it another day or two and try again, but based on what I'm reading in these responses, I'm not optimistic.

The good news is that I started with the trunk because it's easy to start over on it. All I've lost is the week I spent priming and painting, whereas most of my bodywork and prep will still count. I may have to just give in a buy a proper compressor (hopefully I can get a good enough one in 110v) and deal with the mess.

Thanks again for all the replies. This forum is, as always, a huge help.

--Steve

Steve,

The key word is anonymous users. I have read about the roller jobs too. The british car forum where I hang out had a guy or two try this also. From what I read the guys that do this have little to no experience with any of the paint products they use. They are not the guys you want to take advise from.

Again, You will be able to roll acrylic enamel with a high temp reducer and hardner. (high temp reducer will slow the dry time and allow "some " flow out. You will be able to cut and buff the finish.

The paint won't care how it's applied. It doesn't know if it's sprayed or rolled. Only you will know when the paint is ruff as a cobb and full of trash from the roller process. It will dry the same as if you sprayed it. So it will sand and buff the same.

Also, If I rolled a car and sanded it and buffed it I would tell everyone that it looks show quality. But the truth is compared to what? Most likely the answer will be compared to the next guys rolled on paint job. Or when confronted the guy would say " well it's show quality for a rolled on job!"

The reason paint is applied with spray equipment is it is easier to control the end result. Rolled paint will never be trash free. Chunks of lint are bi-product of the process.

If you want to continue to roll the finish do yourself a favor and at least use car paint.

Good luck!

Well my hat is off to you for giving something different a whirl. I have never seriously considered applying paint to a car with a roller or brush, but as they say, times are a changin’. I have painted cars all my adult life, and I’ve gotten results I could not afford to pay for by ‘doing it myself’. The key is patience patience patience. I always painted in my garage, preferring single stage non metallic colors. Then in 1998 a ’71 Superbee I was restoring needed paint, it was Plum Crazy Purple which was a metallic color. Base/clear systems were popular but I had always gone with my old school single stage DuPont Centari acrylic enamel with the recommended hardner. (So I could color sand all the goobers out, and buff to a mirror finish) I did end up painting that Superbee with a PPG base/clear system, and have used base/clear exclusively since. I color sanded and buffed that clear coat just as I used to do with the Centari jobs.

My current project is the first car I did not actually paint myself, as I noted above times are changing and I have neighbors who I have little doubt will complain to city officials or other authorities if I tried to paint something in my garage again. So after doing all the rust repair, panel replacement and bodywork on my ’70 Superbee project I put the car on a trailer and hauled it to the shop my nephew works at and he painted it for me. I almost died not being able to finish the paint on that project myself.

The point of all this is that if it is possible to get a decent finish done with a roller, a guy could still do it in his garage which is something I basically have been banned from doing for one reason or another, so I have an interest in the end result. Even a high quality brush might be successful, the key would be using a paint that flows out adequately, then dries to a rock hard finish suitable for color sanding and buffing. I was amazed at the flaws which could be successfully removed by color sanding. You know if you didn’t want a perfect ‘show winning’ finish this might be the way to go especially if you're one (like me) who just can’t handle having someone else work on your stuff. I would second what others have said, try an automotive paint and do the trunk panel again. I would bet if you aren’t too picky satisfactory results can be obtained. If you do try again, get the paint on and quit messing with it, it will probably start to thicken up quickly depending on your reducer choice and temps. If it’s ugly don’t worry about it, let it harden up and then go at it with a hard block and some 600 grit wet/dry. Let us know how it works.

Check my build thread. I rolled....big mistake. ended up spraying with a low pressure compressor and gun. Paint, compressor and gun for under $200.

Please don't roll and make all these mistakes over again.

http://www.914world.com/bbs2/index.php?sho...c=90174&hl=

That thread link doesn't seem to work...

Here is a shot of the car after the first roll. Came out shiny but not right. The trick is to get the primer coat super smooth with 2500 grit wet n dry. then roll.

I had the same problem you are having when i went to block the finish. if you get good enough to the point where you don't touch the paint after the roll; then you will be good.

Click to view attachment

Believe it or not, a guy here thinned rustoleum paint, rolled it on, waited, wet sanded, did it again, after the third coat, wet sanded and polished. Actually looks very nice on his corvair. It's held up after 3 years. Not saying I would do it, seems like if your that close might as well do it right.

Maybe it's an enamel vs. polyurethane thing.

I want to do a roller job, just to see if I can make it thick enough to sand off perfectly flat.....

nnaaahhh forget it.
Rich