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Keep sanding through clear and basecoats

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  • Member since
    August, 2012
Keep sanding through clear and basecoats
Posted by JMorgan on Saturday, July 08, 2017 12:51 PM

I am painting a car with the only color (navy) that is a close match-- which is only available in flat. I have coated the navy with Testors gloss lacquer. I try to level the lacquer clearcoat job by sanding with very fine grits but keep getting through to the plastic with no warning. I need help, as I have stripped the car twice now and am at my wit's end. What should I do?

  • Member since
    November, 2003
  • From: State of Mississippi. State motto: Virtute et armis (By valor and arms)
Posted by mississippivol on Saturday, July 08, 2017 1:18 PM
Have you been polishing/sanding the the blue color before you clearcoat?
  • Member since
    August, 2012
Posted by JMorgan on Saturday, July 08, 2017 3:29 PM

No, but it is so thin wouldn't the same thing happen?

  • Member since
    August, 2015
  • From: the redlands Fl
Posted by crown r n7 on Saturday, July 08, 2017 3:53 PM

Are you using spray cans or airbrush?

 

 

 

Nick

  • Member since
    November, 2003
  • From: State of Mississippi. State motto: Virtute et armis (By valor and arms)
Posted by mississippivol on Saturday, July 08, 2017 3:57 PM

It can and will at times. You wouldn't have to strip it at that point, though, just re coat and smooth. Since the blue is a flat color, it needs to be sanded/polished out for the gloss cote to level out properly. It's best to sand between coats and build up gradually. One other thing that may be affecting the finish is that the gloss, being a lacquer, may be drying before it can level out, which can cause that rough surface that you're trying to smooth out, especially if the summer temp are high where you are.

  • Member since
    August, 2012
Posted by JMorgan on Saturday, July 08, 2017 4:04 PM

I am using an airbrush for the flat base and a can for the lacquer coat.

  • Member since
    August, 2012
Posted by JMorgan on Saturday, July 08, 2017 4:14 PM

I will try your advice, but I think I will use "Future" for the clearcoat this time. I see that acrylics can be polished with Novus. Does this mean plastics and/or acrylic paints?

  • Member since
    November, 2003
  • From: State of Mississippi. State motto: Virtute et armis (By valor and arms)
Posted by mississippivol on Saturday, July 08, 2017 4:36 PM

I haven't had good results with Future, but that is due to me. I have used Testors custom colors clearcoat lacquer that's in their custom colors line, and it gives a wetter look versus the regular gloss cote and it seems to handle polishing better. Another idea is a satin finish. Carmakers are using that on showcars these days. It's pretty interesting. 

  • Member since
    August, 2015
  • From: the redlands Fl
Posted by crown r n7 on Saturday, July 08, 2017 6:32 PM

I thin my paint more then usual and spray at 10 lbs thin coats if any rough spots i use micro fiber cloth then I use model master clear gloss top coat . Future I use for clear plastic.

 

 

 

Nick

  • Member since
    August, 2012
Posted by JMorgan on Sunday, July 09, 2017 3:58 AM

You use microfiber for polishing flats?

  • Member since
    August, 2015
  • From: the redlands Fl
Posted by crown r n7 on Sunday, July 09, 2017 7:33 AM

Yes after it dries for a good day or so

 

 

 

Nick

  • Member since
    August, 2012
Posted by JMorgan on Monday, July 10, 2017 2:46 AM

Thanks for your help!

  • Member since
    November, 2008
  • From: Florida
Posted by plasticjunkie on Monday, July 10, 2017 7:07 AM

If your paint is enamel then you can mix 50/50 or higher MM gloss enamel to it to get a satin or semi gloss finish. Let it sit for a couple of days and polish it out with extra fine grits to prepare it for several coats of MM gloss enamel. Do not sand but let it cure for at least 5 days then polish with Novus or any automotive haze and scratch remover.

This is how I paint my Blue Angels aircraft and the finish is smooth as glass asfter a light polish with no sanding.

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Monday, July 10, 2017 8:41 AM

The neat thing about this problem today is that it is becoming easier to find really fine sandpaper and sanding pads!  Used to be it was hard to find anything finer than #600, even at auto parts stores.  Now, auto parts stores carry considerably finer sandpaper, and a decent hobby shop or craft store carries stuff so fine I am wondering if it is any better than paper toweling.  I picked up an assortment pack at Hobby Lobby recently that went to something like #10,000!

Don Stauffer in Minnesota

  • Member since
    August, 2012
Posted by JMorgan on Tuesday, July 11, 2017 2:55 PM

I have tried using microfiber for polishing Testors MM enamel flat, but it seems to have no effect. I would like anything but sandpaper because it keeps getting through the paint.

  • Member since
    August, 2015
  • From: the redlands Fl
Posted by crown r n7 on Tuesday, July 11, 2017 3:10 PM

I'm sorry it didn't help it works for me to even out the rough spots of the flat primer 

 

 

 

Nick

  • Member since
    May, 2009
  • From: Poland
Posted by Pawel on Tuesday, July 11, 2017 3:15 PM

Hello!

I'm no expert, but I have managed not to go through the layers while doing a high gloss on my VW Bus. What I did I have built up a few layers of the base paint, then I put on a few layers of clear ot top of that and I only sanded very lightly between the coats. After everything dried really well I did some sanding (wet!) and I was watching the dust on the sandpaper very closely. When I thought I started to see coloured dust, meaning I have reached the paint layer through the clear coat I stoped sanding, let it dry for a while and then applied some more clear. I could then go on with the sanding if necessary, but usually the new layer leveled everything pretty nicely. I hope it helps you, good luck with your build and have a nice day

PaweĊ‚

All comments and critique welcomed. Thanks for your honest opinions!

www.vietnam.net.pl

  • Member since
    August, 2012
Posted by JMorgan on Tuesday, July 11, 2017 3:20 PM

That is a good tip I definitely will try. Thanks.

  • Member since
    December, 2013
  • From: Orlando Florida
Posted by route62 on Wednesday, July 12, 2017 6:43 AM

Here is a great tutorial I found years ago and still use this method to get glass smooth finishes

http://italianhorses.net/Tutorials/PerfectPaint/paint.htm

  • Member since
    November, 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Wednesday, July 12, 2017 12:05 PM

JMorgan

I have tried using microfiber for polishing Testors MM enamel flat, but it seems to have no effect. I would like anything but sandpaper because it keeps getting through the paint.

 

What is the finest grit you used?

Don Stauffer in Minnesota

  • Member since
    August, 2012
Posted by JMorgan on Wednesday, July 12, 2017 1:00 PM

2500 grit. One of the finest at Autozone.

  • Member since
    March, 2003
  • From: Virginia
Posted by Wingman_kz on Wednesday, July 12, 2017 1:56 PM

A couple of suggestions. Get the color coat smooth before shooting clear. The color doesn't have to be gloss. Modern auto paints are mostly flat or satin before the clear is applied and the majority of modern vehicles are clear coated. Clear will smooth out a satin or flat finish as long as the color is smooth to begin with. Flat or semi flat doesn't have to be rough.

Build up more clear coat. Make it thicker before you start sanding. If you're using the black can Testors you may want to try the Custom Lacquer or whatever they call it. It will level and flow better. Shoot several coats and let it cure. Sand lightly until you get it fairly smooth. Be gentle and go slow. Keep a watch on your sand paper and if you see any color stop and do another area before you sand through the color. Once you get the whole body done, shoot more clear and repeat. Of course, you have to do this evenly on the whole body.

Use a small sanding block, don't just hold the sandpaper in your fingers. I use some hard black rubber cut into different sizes but mostly just use one about an inch long, 3/8 inch wide and 3/16 thick. I also rounded two of the long sides. So, when I use sandpaper I cut it into 1 inch squares. Sounds small but that would equate to a long board on a full size car. Wet sanding is generally better than dry. Makes the paper more flexible and lubricates. Just a little tub of water with a drop of dishwashing liquid is all you need.

Invest in a set of Micro Mesh Polishing Cloths. Start with the most coarse grit and patiently work your way through to the finest making sure to remove all scratches from the previous grit before moving on. You can finish up with Novus Plastic Polish if you like. I cut the sheets into quarters and if you take care of them they'll last a long time. I use them dry and brush them off with an old toothbrush if they load up with paint.

You could also decant the clear from the spray can and shoot it through your airbrush. Would give you more control. If you do that, paint in several sessions making your clear progressively thinner and shooting thicker coats. Just don't get carried away. The thinner the paint and thicker the coats the better it will flow and level and the less sanding you'll need to do.

You'll get it. Just hang in there.

            

  • Member since
    August, 2012
Posted by JMorgan on Wednesday, July 12, 2017 3:19 PM

So, Novus plastic polish works on paint too (as per your recent post)? Also, how will progressively thinner coats of paint give a thicker application?

  • Member since
    August, 2012
Posted by JMorgan on Wednesday, July 12, 2017 3:21 PM

BTW, what part of Virginia are you from? I am a Virginian too.

  • Member since
    March, 2003
  • From: Virginia
Posted by Wingman_kz on Wednesday, July 12, 2017 4:58 PM

I try to make it so I either don't have to sand or do very little. Both color and clear. For one thing, if your color is metallic it's next to impossible to sand it and not mess up the color. You know, uncovering the small flakes, disrupting the way the flakes layed down. So the best thing to do is to learn to handle both this way.

When I paint car bodies I normally use a bottom feed airbrush with a bottle. That way I have plenty of paint and don't have to stop. I also almost always use lacquer. Either automotive touch up paint or fingernail polish. To a degree it works with enamels too but you generally can't thin enamels as much as lacquers. Tamiya's bottled acrylics will spray pretty much like lacquers too. You can even use lacquer thinner with them.

So, you get your mix right. Whatever you normally use. The milk consistency thing or whatever. Make sure you have enough mixed to do the complete job allowing for extra coats. You lay down your light coats to build up color. Or clear. Once you have complete coverage thin your paint a little more, whether it's clear or color, wait 10 minutes or so and spray a heavier coat. Not running heavy but heavy enough that you can cover with one coat remembering that the paint is thinner now so don't get carried away. If everything is going well and looking smooth wait a few minutes and lay down another coat. If you're seeing orange peel or other texture then immediately lay down another wet coat to see if it levels out. If it doesn't, stop, let it cure/dry completely and sand it out then recoat with your slightly thinner mix. You don't have to go back to your original mix once you've reached this point unless your have to strip it all and start over.

If you're shooting the color coats and it looks good or good enough that you can color sand to smooth it out then stop right here and wait for it to dry, then sand lightly to smooth. If it's metallic and you have to sand you'll have to recoat or it won't look right. You can do that with a fairly thin mix, you just need to cover enough to make it look uniform.

But, if you're doing the clear coats, then every 10 minutes or so go back and shoot another coat. Every two or three coats make your paint(clear) a little thinner. By the time you're done your mix will probably be 2/3 thinner and 1/3 paint. You can get away with that with lacquer. Enamel takes much longer to dry and you can't thin nearly as much as lacquer. Tamiya bottled acrylic isn't that much different from lacquer when thinned with lacquer thinner and Tamiya supports using lacquer thinner with those paints.

The point of all this is to make your top coats self-level so you have to do little to no sanding. If you're going for a show car finish then you're going to have to do a little polishing regardless but once you learn how to do this it doesn't take much to get a glass smooth slick finish. If it's going on the shelf and not the show, you can get the paint smooth enough to not bother with sanding/polishing. It will work.

I'm not an instructor and don't have hands on experiencing with teaching so I can only speak from my experience but, when I was beginning and learning I tended to not build up the clear thick enough. Or color for that matter.  The cool thing about lacquer is how thin it is once it's dry and how hard it is. Enamels are much thicker and softer. Tamiya acrylic will be thin like lacquer but softer. You can still do this with enamels too, you just can't thin as much or shoot as heavy a coat or it will get out of control.

You have to learn how much is enough and that only comes with practice. When you have a good solid color, give it another wet coat. With clear, give it 2 or 3. Over thinning lets you shoot fairly heavy wet coats without building up too thick because the extra thinner keeps it from drying too quickly and level. Then the thinner evaporates, the paint cures and it's much thinner than it looked originally.  You have to give at least 10 minutes or so between wet coats at this point to let it dry but you don't want to wait too long so the coats will bond or burn together. Again, enamels don't quite work that way. You have to let it dry or it will sag with another wet coat.

This is a real book isn't it? Sorry about that. As an aside, my favorite clear of anything I've ever used is clear finger nail polish with Rimmel 60 Seconds being my favorite. It's pure clear and doesn't yellow over time. A couple of bottles is plenty for a single car. It usually costs less than hobby paints and sprays very well. Also, a gravity feed brush will work just fine. Just make sure you keep your paints ready to use so you can refill the cup at any time and don't start a coat without enough in the cup to finish it. I'm just north of Roanoke btw.

Tony

            

  • Member since
    March, 2003
  • From: Virginia
Posted by Wingman_kz on Wednesday, July 12, 2017 5:10 PM

And yes, you can use Novus on paint. You can even paint over it once you've used it and polished it off. Not that there's much of a reason too but if you should happen to find that you've sanded through somewhere and need to touch up, you can without worrying about paint not sticking or fish eyeing because there's no silicone or anything in this polish. It's kind of like using a scratch remover type polish on a full size car. I think the Micro Mesh cloths go up to 12000 grit. Seems very fine and it is but you can get an even brighter shine if you then polish with Novus. Maybe it's more like using a detailer type wax. It works.

            

  • Member since
    August, 2012
Posted by JMorgan on Thursday, July 13, 2017 11:35 AM

Quite an explanation. I certainly want to keep sanding to a minimum so I'll give it a try. Thank you.

  • Member since
    March, 2003
  • From: Virginia
Posted by Wingman_kz on Friday, July 14, 2017 7:38 AM
Sorry :-) I've had a cold and was slightly medicated

            

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