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How smooth is smooth is smooth?

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  • Member since
    July 2018
How smooth is smooth is smooth?
Posted by JustPlaneJon on Wednesday, March 25, 2020 8:11 AM

I'm posting on the airliners section because we are usually going for smooth and glossy paint jobs. My question is how do you all manage the primer coat? Assuming the end goal for the model is a gloss, out-of-factory look.

It seems there are competing objectives. On the one hand we supposedly want the primer to provide a good base for the paint "to grip onto," indicating we want to leave some degree of grittiness. On the other hand we want a perfectly smooth finish, so that indicates we would want the smoothest primer coat possible. So how do we manage these seemingly disparate objectives?

My initial thought is we should make the primer as smooth as possible and that the concern over providing a "grip surface" is overrated. Especially if using acrylic or lacquer paints that dry quickly. And by smooth as possible I mean smooth up to a polished 12,000 grit micromesh or better. What are your thoughts and experience on this? 

 

 

  • Member since
    September 2012
Posted by GMorrison on Wednesday, March 25, 2020 9:24 AM

Have you ever had paint peel to reveal an intact primer coat? I don';t think I have. And if it does, the finish coat probably hadn't cured.

OTOH, peeling up to reveal bare plastic, and the underside of the chip being primer colored, is more usual.

Getting the primer to bond to the plastic is the battle.

Then sand it smooth. Clean it really well and the finish coats should bond ust fine.

 

Bill

 Modeling is an excuse to buy books.

 

  • Member since
    November 2003
  • From: State of Mississippi. State motto: Virtute et armis (By valor and arms)
Posted by mississippivol on Wednesday, March 25, 2020 9:53 AM
I'm not a big user of primers, I think enamels and lacquers adhere just fine. I don't think you can forgo it in regards to acrylics, though. I do think the primer needs to be smoothed, I noticed more orange peel when I hadn't.
  • Member since
    March 2015
  • From: Close to Chicago
Posted by JohnnyK on Wednesday, March 25, 2020 10:10 AM

I only use primers on areas where I have used filler and that required extensive sanding. The primer helps smooth out the sanding marks and seals the filler. After the primer has cured I wet sand it with fine sandpaper.

Your comments and questions are always welcome.

  • Member since
    October 2019
  • From: New Braunfels, Texas
Posted by Tanker-Builder on Wednesday, March 25, 2020 11:07 AM

Hi J.P.Jon;

 To give you my answer. If I can get away without primer I sure will try to. If not then I use Rustoleum primer in the Rattle Can. It sticks and I make it match the finish on my neighbor's new baby's Bottom!. So smooth it feels like silk!

  • Member since
    November 2009
  • From: Twin Cities of Minnesota
Posted by Don Stauffer on Wednesday, March 25, 2020 1:57 PM

JustPlaneJon

I'm posting on the airliners section because we are usually going for smooth and glossy paint jobs. My question is how do you all manage the primer coat? Assuming the end goal for the model is a gloss, out-of-factory look.

It seems there are competing objectives. On the one hand we supposedly want the primer to provide a good base for the paint "to grip onto," indicating we want to leave some degree of grittiness. On the other hand we want a perfectly smooth finish, so that indicates we would want the smoothest primer coat possible. So how do we manage these seemingly disparate objectives?

My initial thought is we should make the primer as smooth as possible and that the concern over providing a "grip surface" is overrated. Especially if using acrylic or lacquer paints that dry quickly. And by smooth as possible I mean smooth up to a polished 12,000 grit micromesh or better. What are your thoughts and experience on this? 

 

 

 

Exactly.

I sometimes give it more than one coat of primer, to check seam filling.  I prime again after finding and fixing flaws.  I only sand the last coat of primer.  The adhesion of primer is for the interface between the primer and the plastic.  With most primers, there is little problem with later coats of paint. I know there are exceptions to that, but I avoid using primers that have that problem.

 

Don Stauffer in Minnesota

  • Member since
    July 2018
Posted by JustPlaneJon on Wednesday, March 25, 2020 3:16 PM
Thanks everyone for your input. That all makes sense. And I suppose if you use primer then it would be good to put on a few coats to give yourself enough material to work with and sand/polish down to a nice perfect smooth surface to apply the the paint.
  • Member since
    October 2019
  • From: New Braunfels, Texas
Posted by Tanker-Builder on Thursday, March 26, 2020 10:40 AM

Hi;

    Pretty much on track there. Now on the few airliners I have, they all get four topcoats in a misting action . 15% paint,85% thinner. I have used this finish method on real cars over the years and one plane ( My old Cessna 180 float plane ( Yup ,Just like the Monogram Kit!).

    Never had problems with sheen, shine and durability. The Black stripe on the Cessna was Semi-Gloss Automotive paint. It was still on the plane when I sold it! Many times I use real touch-up paint on my models. I just like the way it flows. This is done at a friend's house. He has a dedicated paint booth!

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