stunthanger.com

Building Tips and technical articles. => Building techniques => Topic started by: Kreth on April 08, 2006, 08:36:47 AM

Title: Paint
Post by: Kreth on April 08, 2006, 08:36:47 AM

Has anyone used Acrylic Urethane as trim over a base of Acrylic Enamel?  I am worried about softening  etc. of the base.

Kreth  :)

Title: Re: Paint
Post by: Bill Little on April 08, 2006, 11:21:38 AM

Sorry, Kreth.  I've never used Acrylic Enamel on any of my planes.  :(

Title: Re: Paint
Post by: Kreth on April 08, 2006, 03:21:34 PM

I have used acrylic enamel for years, and it is entirely fuelproof.  Arlan my son shot some black acrylic enamel on a fuselage and wanted to do silver trim for the canopy.

I have some acrylic polyurethane in silver and was not sure about compatability.

 :) Kreth

Title: Re: Paint
Post by: RC Storick on April 08, 2006, 04:13:35 PM

Quote from: Kreth on April 08, 2006, 03:21:34 PM

I have used acrylic enamel for years, and it is entirely fuelproof.  Arlan my son shot some black acrylic enamel on a fuselage and wanted to do silver trim for the canopy.

I have some acrylic polyurethane in silver and was not sure about compatability.

 :) Kreth

I know somethings about paint.There are two kinds. Mechanical bond and chemical bond. Your chemical bond paint are your lacquer's and dopes. You mechanical bonds are enamel and urethanes. You can put any mechanical bond paint over chemical bond but never put chemical bond over mechanical.

The chemical bond paint are usually thinned with a MEK or lacquer thinner while the mechanical bond paint are thinned with Naphtha based thinners or mineral spirits.

Title: Re: Paint
Post by: Kreth on April 08, 2006, 05:12:08 PM

Well, that is an answer to a question but not what I am looking for.  Have we got any body shop men out there?   Has anyone shot catalyzed automotive acrylic polyurethane over fresh (two or three day old) catalyzed automotive acrylic enamel?

Thanks,
Kreth  :)   

Title: Re: Paint
Post by: RC Storick on April 08, 2006, 05:18:49 PM

The answer is right in the response I stated. It should work. However I would try a test piece. Both of those paints are mechanical bond paints. Scuff it up first with gray scotch bright (600) as stated it is mechanical bond. It needs tooth to stick. I do something that is not suppose to be done ,like putting Urethane (mechanical bond) over dope (chemical bond) I do it all the time with no ill effects. I don't think it would matter to do it the other way around either. Meaning catalyzed paint under dope. Except it would be difficult to make it stick. I hope this has now answered you question.

Dopes and Lacquers are chem bond

enamels and urethanes are mechanical. So what I am saying is if the paints are of like types the should work together.

In the old days of Aero Gloss you can paint Sig or Randolf over it but never Aero over anything as it has MEK in it.

Title: Re: Paint
Post by: Kreth on April 08, 2006, 05:47:49 PM

I understand about chemical and mechanical bonds.  I also understand about ability of paints to grip or stick to something - needing to be scuffed with something such as 600 grit or scotchbrite.  Hot thinners such as lacquer thinner and it's cousins dope thinner will soften most any enamel or polyurethane.  Some polyurethane thinners will even soften lacquers - so the question.

What I was looking for was a definite - I have done it before with no problems.

Thanks anyway,

Kreth