Sag in SS metallic base, should I sand it before I clear it or will it make it worse?

racin69z

New Member
I am spraying urethane single stage blue metallic and am going to clear over it in the morning with universal clear. I got a sag in a very noticeable spot. Only dang run I got on the whole deal. I am afraid of cutting into it and having the metallic look all weird. But, it looks weird on the bottom side of the run, so I am kind of thinking about trying to block it down a little bit before I shoot the clear.

The single stage was activated and had metallic stabilizer mixed in it as well.

Any suggestions would be appreciated

Lynn
 

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crashtech

Combo Man
You can't sand it without spraying another coat or two over it, that's for sure. If you simply sand it and clear it, it will be worse than just leaving it be. I think it could probably be spotted in, but it's been over 30 years since I shot a single stage metallic, so maybe some other oldtimer here could give you advice on the best procedure.
 

racin69z

New Member
Thats what I was afraid of. Its not awful, but it really bugs me. Of all places, right behind the passenger side door.

Thanks for the advice
 

crashtech

Combo Man
Maybe the maker of the paint has a repair procedure in their TDS, it wouldn't hurt to check. It might be easier to repair it after clearing, since you would be disturbing less of the metallic with sanding.
 

racin69z

New Member
The problem is, there is a dark spot under the run. I think it will show through. I may go shoot a "test run"panel! I have a little paing left in the mixing cup
 

texasking

Active Member
Reading this reminds me of when I used to blend acrylic enamel, so I guess that makes me an oldtimer :) Just block the run flat with 600 or finer, keeping the sanded area small as possible. Spray a couple light coats until the spot is gone, covering any sand scratches. If the blend is showing, reduce it about 25-50%, and just dust the edges very lightly.
 

racin69z

New Member
Well CRAP! I went out in the shop to make a test run, and the dang paint has solvent pop. Now I have to figure that out. It is not like craters, just very tiny bubbles right at the surface
 

crashtech

Combo Man
Reading this reminds me of when I used to blend acrylic enamel, so I guess that makes me an oldtimer :) Just block the run flat with 600 or finer, keeping the sanded area small as possible. Spray a couple light coats until the spot is gone, covering any sand scratches. If the blend is showing, reduce it about 25-50%, and just dust the edges very lightly.
I was thinking it was pretty much like a base blend, but it's been so long. Most of the blending we did with SS was double gun, one with paint, the other with clear. I wasn't sure if repair blending on partially cured material ought to be done with a bit of blender or not, due to the viscosity of the material.
 

jcclark

Oldtimer
I just painted a hood silver, while putting on the base I noticed a piece of dirt.
I let it dry real good and sanded it off with 600 grit, then applied 3 coats of base over it.
Big mistake! It looked fine after the clear coat but out in the sun it appeared as a dark spot.
If you ever sand a high metallic base make sure you cover it with a little intercoat clear or
regular clear before adding more base. Somehow sanding changes it. I don't understand it
but I am right now repainting the hood after blocking it back down.
This time I used Bulldog on it before applying my new base to seal any scratches.
so far it looks good.
 

Chris_Hamilton

Trying to be the best me, I can be
Please don't take this as criticism but I gotta ask, why use a single stage to start with especially if you are planning to clear it? Single stage urethanes have their place but only in solid colors. Metallics are a whole different story. Spraying a SS metallic is not easy. Repair is not easy. And when you put clear on top you defeat the only good thing about a single stage. And when clearing it the cost is now the same as it would have been using a basecoat, instead of SS.
Ok rant over. :)
 

jcclark

Oldtimer
I think single stage is still cheaper but not enough to matter.
On high metallics SS, a clear coat is good insurance if you are going to cut and buff.
You don't want to sand into the metallics before buffing, it can cause problems.
A lot of people think SS looks better, I tend to agree, SS with clear coat is also way more durable than base coat/clearcoat.
I don't use SS for my collision car work, but for my own car I might.
It's just a personal preference for me, I like the depth of color it gives.
 

Chris_Hamilton

Trying to be the best me, I can be
On high metallics SS, a clear coat is good insurance if you are going to cut and buff.
You've just defeated the purpose of SS. Just doesn't make sense to me.

SS with clear coat is also way more durable than base coat/clearcoat.
Properly done base/clear job will last 25 years or more.

To each his own but it's a no brainer if you are shooting a metallic. Not to mention film build when clearing a SS.
 

texasking

Active Member
I've sprayed well over a hundred SS metallic completes, urethane and enamel. I've also sprayed dozens of complete lacquer jobs, many metallic. There is no way I would even consider shooting another one with what is available now. SS is not cheap, anymore. Go buy some Concept or acrylic enamel and the cost is just as high. Take SPI's red SS vs. BC/CC, as an example. If you sprayed the same amount of ounces of each, the BC/CC would be cheaper.
 
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racin69z

New Member
Chris, no offense taken at all. I am wondering the same thing right now. I bought two jobs worth of materials at once last time. I have materials bought for another single stage metallic job that I am now dreading. I have been using the Kirker/Summit single stage paint for the last several jobs I have done with and without clear. I have been very happy with it. For the money I don't think it can be beat. My 72 is painted with chroma base and 3 coats chromaclear sanded +2 more coats. My sons 84 is painted with the kirker single stage sanded with 600 and 3 coats spi universal clear and his truck has better shine and depth than mine.

When it came time to do these 2 jobs I am doing now, I just ordered the single stage out of habit. I've only used actual base clear a few times, nothing against it. I should have bought base clear no doubt.

I wound up sanding the sag a little and spotted it with my airbrush. Then I sanded the solvent pop out lightly with 600 grit the lightly hit it with a grey scuff pad. Then I cleared it.

I got a little bit of very minor solvent pop again on the first coat, so I just stopped there. I am going to open it up with some 600 and get it out in the sun. Eventually that should get all the solvent out I hope.

I still have stripes to do, so i already planned on another round of clear. Do you guys think that sanding it and getting it out in the sun will work?

Thanks
Lynn
 

crashtech

Combo Man
One coat of clear is very likely not enough to do any real sanding. You might hit it lightly with 600 while avoiding edges, then rub it down with a grey scuff pad. Then you can get some mils of clear on there. If you try to sand it flat (remove all texture) you will break through, almost guaranteed.
 

racin69z

New Member
I got into the pop and didn't want to add more layers to seal it off. I wanted to get something over the metallic while within the recoat window. I know there wont be much thickness to play with.

Will sanding even help get me out of the pop? I figured it may help a little. This time the pop was very minor. Not near as bad as last nights. Maybe I just need to get it in the sun. I've gotta break it open before I stripe and clear it again.
 

crashtech

Combo Man
Cured urethane has to be sanded or what you put over it won't stick very well. So I guess I'm not sure why you are asking about sanding, it's not optional now.
 

crashtech

Combo Man
I guess I feel like I ought to add that it's exactly for that reason that I wouldn't stop spraying after one coat of clear. At least two need to get on there no matter what if any sanding is to be done without breaking through. Solvent pop is usually from "skinning over," or flashing too quickly, so one trick to try is to start with a slower activator and/or reducer. Having some retarder on hand when doing large jobs can be a life saver as well. If you get in a jam again, you might try calling Barry and telling him what's happening, he may have been able to line out a procedure that could have saved you some work.
 

racin69z

New Member
Sorry if I wasn't clear. I am planning on sanding before the next coat, I know there is very little film build over my color coat. I just dont know what the best move forward from here is to get this solvent pop behind me. I didnt know if I should scuff it now and get it in the sun to dry out the extra solvent, or just get it in the sun and sand right before I re clear. I have some stripes to paint at the color breaks, and then I would like to clear it and be done. I remember reading that urethane scratches can close back up as the finish cures so that would have me sanding twice.

I have a little time for this thing to cure l, but not a ton. We are trying to get it running by the 4th of July.

The only other time in had solvent pop it was on a flow coat job with medium solids clear. I sanded and let it dry for a week and then sanded again. That was much worse. They were like fisheye craters. What I have going on now is like sand at the top of the surface. I am certain it's not dust because it was raining when I was clearing and the shop is clean. It is not all over either. It's worse where i had the original run which makes sense since the paint is much thicker there this the run.

Unless I hear different I am going to give it about a week in the sun, scuff with 600 grit and then stripe and clear--and not on a humid ass rainy day.
 
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