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How many coats?

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  • Member since
    February, 2016
How many coats?
Posted by smitherreen on Tuesday, February 07, 2017 12:27 PM

For the guys who prime, paint, sand, add finish coats, sand, and then rub out. How many wet finished coats do you average to make sure you don't wet sand or rub through to the primer? Tom

  • Member since
    August, 2016
  • From: Wisconsin
Posted by jwrass14 on Tuesday, February 07, 2017 10:27 PM

Tom,

This is kind of a loaded question part of which I don't really understand, However I will take it from spraying clear thru polishing the way I do it. All of my prep and paint proceedures come from 1:1 (see Profile) practices and they work for me. 1 coat of a automotive high solids clear will measure approximately 1 mil of film thickness. Just for grins lets say one coat of rattle can clear would be .5 mil of film thickness.

On average sanding will remove about .5 mils of material and buffing will remove about .3, lets round it up to 1 mil removed in the cut and buff process.

The target for me with clear is to leave 1 to 1.5 mils after the cut and buff process, that's 1:1. On a model you dont' need that much film thickness due to you are not dealing with UV and overall element protection. Much of the number of clear coats you apply also depends on the type of material you are using i.e. Enamel, Lacquer, Urethane. I would say a good rule of thumb would be 4 to 6 coats of clear before you cut and buff. Paint on body lines and raised areas naturally lay flat, there really is no need to sand those areas at all other than to remove any trash that may have landed on those area's. When polishing run fine line tape on edges, body lines or any areas that seem vulnerable to possible rubbing thru the clear coat. In the final phase of the rubbing process the areas that were protected by tape will come up to the shine of the large areas with little effort without rubbing thru the clear.

Hopefully this helps.... 

 

Jimmy "RASS"   

"I Have Flying Monkey's And I'm Not Afraid To Use Them"

  • Member since
    May, 2015
Posted by Goofy62 on Wednesday, February 08, 2017 9:22 AM

I usually use as many as 5 or 6 light coats of primer, mostly because I'm using automotive lacquers & I want to be positive that I have a good barrier against crazing.

The number of color coats depends on how well the paint covers.

I usually get by with 3 or 4 color coats.

I agree absolutely with Jimmy on the clear coats.

I use Duplicolor rattle can clear which goes on very thinly, so 5 or 6 coats is not out of the question.

The more clear you can get away with, without hiding detail, the better it will be when it comes to polishing.

 

Steve

  • Member since
    February, 2016
Posted by smitherreen on Wednesday, February 08, 2017 1:48 PM
First off thanks to the both of you. If I can go a little bit deeper without driving you crazy, here is really what I am getting at now after your replies: 1) I take it you wet sand after last primer coat? 2) What about the final color, do you sand in between each coat or on the last coat? 3) Do you rub it out then prior to clearcoat? 4) Lastly on the Clear Coat, spray as many layers as you need and then follow up with wet sand and rubbing out? Thanks for sticking with me. Tom
  • Member since
    December, 2007
  • From: Oregon: Tree Country.
Posted by Treehugger Dave on Wednesday, February 08, 2017 4:51 PM

I have a different take on all of this. I haven't sanded a paint job in decades.

First off, great preparation is an absolute must and so is a good quality primer and paints and a great repeatable paint system where its a simple thing to do.

After my last coat of clear whether it's acrylics, lacquer ot auto urethanes, I wait 16 - 20 hours and begin rubbing the paint out to a glass like finish.

For me waiting too long for the paint to dry is the worst thing I could do.

Paint is still "Fluid" when it's fresh and can be "Mechanically smoothed to a glass like finish by simply "Rubbing" it smooth. No sandpaper whatsoever except on body filler and primer - so simple and it gives a gorgeous finish. You just have to use the right materials, and have a system of painting that never fails you.

Makes model building so much more enjoyable Thumbs Up.

I love Mecum Auctions and Barrett/Jackson auctions.

I bought all the model stuff I wanted for Christmas because no one else would spend that much on me Laugh Laugh

 

                                     

 

 

  • Member since
    December, 2003
  • From: Nova Scotia
Posted by Bainford on Thursday, February 09, 2017 8:06 AM

smitherreen
First off thanks to the both of you. If I can go a little bit deeper without driving you crazy, here is really what I am getting at now after your replies: 1) I take it you wet sand after last primer coat? 2) What about the final color, do you sand in between each coat or on the last coat? 3) Do you rub it out then prior to clearcoat? 4) Lastly on the Clear Coat, spray as many layers as you need and then follow up with wet sand and rubbing out? Thanks for sticking with me. Tom

I'm not an expert on painting, but I've been doing this for quite some time and I manage to get good results, so I will answer your questions as best as I can.

1) It is not always necessary to sand your last primer coat if everything looks good. Nonetheless I usually give it a very quick sand with 600 grit paper, used wet. I wouldn't really call this a sanding, just a bit of a rub to ensure there are no local high spots or junk in the primer, etc. Wash the body thoroughly afterwards, before painting.

2) Personally I do not colour sand between colour coats unless I have managed to get some significant junk in the paint or it has all gone horribly wrong somehow and turned out pebbly or badly orange peeled, but this is rare. In these cases I will let the paint cure then colour sand before the last wet coat, but this hardly ever happens. Never colour sand metallic paint. If a metallic paint job goes irretrievably south I strip and start over.

3) Here is where I differ from many of the painters on this forum; I rarely use clear coat (personal preference) except for on metallic paint. And the only reason I use it then is, as mentioned above, you can't colour sand directly on metallic paint. However, I also rarely use metallic paint, so I polish out the colour coat with micro mesh pads and Tamiya polish and finish off with Tamiya wax.

If I was to use a clear coat, I would lightly colour sand the colour coat just enough to ensure it is flatened out, remove any junk in the paint, and ensure ridges from any masking operations are smoothed out.

4) Yes.

One thing I'm sure your are discovering is that, though there are a few hard and fast rules that must be followed when painting, many modellers have developed their own very personal process for getting the job done. Over time you will develope your own process that you are comfortable with. And as I mentioned, I'm no expert but this is what works for me.

Power matters in the straights.
Lightness matters everywhere. - Colin Chapman

Trevor

  • Member since
    May, 2015
Posted by Goofy62 on Thursday, February 09, 2017 9:19 AM

I pretty much agree with "Bainford".

All of that sanding between every coat stuff is really not necessary unless it's somehow warranted.

In other words, unless there is dirt in the paint or some fairly heavy orange peel, it's pretty much a waste of time.

So, unless there are imperfections some where along the line during the painting process, I save my polishing for after the last clear coat.

I do almost zero wet sanding on my paint jobs.

I polish at the end with "Micro Mesh" pads & "Novus" polishes.

 

Steve

 

  • Member since
    August, 2016
  • From: Wisconsin
Posted by jwrass14 on Thursday, February 09, 2017 8:41 PM

smitherreen
First off thanks to the both of you. If I can go a little bit deeper without driving you crazy, here is really what I am getting at now after your replies: 1) I take it you wet sand after last primer coat? 2) What about the final color, do you sand in between each coat or on the last coat? 3) Do you rub it out then prior to clearcoat? 4) Lastly on the Clear Coat, spray as many layers as you need and then follow up with wet sand and rubbing out? Thanks for sticking with me. Tom
 

Tom,

I'll give my two cents on your questions, #1) I Wet and Dry sand, Mostly wet sand though. About an hour before you wet sand pour your water into a container, add a few drops of dish soap (Ivory or Dawn Classic) along with your sand paper. The soap acts like a lubricant and helps with paper loading it also softens your paper which makes it easier to work with. Ivory and Dawn are the only dish soaps I use, All dish soaps have a scent, however the fancy ones in many cases use perfumes that contain oils... Oils = fish eyes. Ivory and Dawn classic do not. 

#2) The only sanding I do between coats is if I see some trash in the paint.... A very light touch here. I sand on the final coat before the clear coat, HOWEVER never directly sand on metallic or any exotic finishes i.e. Kandies, Pearls etc as you will disturb the micas which gives the apperance of un-evenness or burn. After I spray my color coat I spray a couple of coats of clear as a barrier coat to protect those types of finishes. I then lighty sand that barrier coat before I spray the clear coats. You do not have to apply a clear coat to solid colors.

#3) I do not rub out. I scuff the barrier coat as discribed in #2

#4) Yes

Never be afraid to ask questions! No matter how many! We have all been there! I can only speak for myself... I'll help anyway I can.

Jimmy "RASS"

"I Have Flying Monkey's And I'm Not Afraid To Use Them"

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