Help With Enamel/Lacquer Compatibility

[sequoiaranger]

I have used Floquil (lacquer) paints on a project, but found Floquil Flat a bust. I plan to use Pactra 'Namel Flat over it, but on a test piece of cardboard, the paint and lacquer "reacted". I put a LOT of work into my topcoat (See "Blordiator" thread) and absolutely cannot afford a mess that would require a total re-paint.

So my question is: if I use an Acrylic clear coat over the lacquer, would that form a proper barrier to the enamel Flat coat (s) that I plan to put over it? Has any one done that (successfully or not)?

[Mossie]

I think if you use an acrylic clear coat, it's probably going to react with the enamel.  Acrylics really don't coat enamels well at all, Future would be your best bet, I've never heard of it reacting to any paint finish.  I've used Future/Klear before on two projects to 'seal' them, works well.

First project, I needed a matt finish & only had an enamel varnish.  Problems don't usually occur from coating enamels with acrylic (it's the opposite you've got to watch for), but I wanted to be on the safe side.  I was using Klear as a base for the decals anyway, so it wasn't any extra work.  No problems.

Second project, I had to recover a compatibility problem.  I use Halfrod primer (& automotive paint here in the UK) & acrylics usually go on it without a problem.  I used a Humbrol Acrylic spray can, there was a small amount of cracking in the paint surface.  I sanded the offending areas back to the primer, then used a coat of Klear.  The acrylic went on beautifully after that.

[sequoiaranger]

Thanks for responding. The way I read the following words, though, they contradict. I **THINK** you say that coating enamels with acrylic is a bad thing, then a good thing.

> Acrylics really don't coat enamels well at all, ........[then]...... Problems don't usually occur from coating enamels with acrylic (it's the opposite you've got to watch for), but I wanted to be on the safe side. <

So which is it?

I've used an acrylic flat coat on several enamel projects, but the results were mildly dis-satisfactory. I have had great success in the past with Pactra 'Namel Clear Flat, though it tends to "beige" the underlying coats if too many coats are put on.  I was hoping to avoid that with the new clear acrylic flat finishes, but I have had problems.

The way the layers are on my current project: I have sprayed lacquer coats for the camo (with some hand-painted bits of enamel on top), then lacquer clear coat over all that for decal application (no reaction from the enamel then).

You didn't mention acrylic reaction to lacquer. The reason I had thought of using acrylics was that they should be chemically neutral to both enamel and lacquer, so could form a neutral barrier between the two, often highly-reactive coatings (enamel and lacquer).

[sequoiaranger]

Though I haven't yet put my experimental results to work on my Blordiator, my test-bed for paint compatibility has me less worried. I sprayed both wings of a painting-dummy aircraft with the Blordiator Floquil colors (lacquer) and "Alclad II Lacquer Clear Base" as applied to my Blordiator. I then painted one wing with "Tamiya X-22 Acrylic Clear" and didn't paint the other. I then applied thinned "Pactra 'Namel Clear Flat" enamel over both wings, spraying heavily to see if any interaction took place.

When I was done and they dried, they both looked the same. There was no "interaction" between the acrylic and the lacquer, nor the enamel and the acrylic on the one side, nor the enamel and lacquer on the other side. WHEW! I guess one of the secrets is PATIENCE to allow everything to dry completely (well, DUH!).

I was fearful that the complicated and time-consuming "harbor" camo on my Blordiator would be fouled up by interaction between the "incompatible" paints, but that seems not the case. I am going to coat my Blordiator with the clear acrylic prior to application of the enamel flat just in case. It also will be an additional layer that will help blur the edges of my "thick" homemade decals. A win-win.

I am hoping that the "beige" cast to previous use of Pactra Gloss and Pactra Flat was due to BOTH of them being slightly brown in the bottle, and the standard four layers (two gloss prior to decal application and two flat afterwards) compounded the tinting. I think that the truly clear gloss coats I have applied so far will limit the "beige"-ing (not to be confused with the capital of China) when I use the Pactra Flat.

[Mossie]

Oops, sorry mixed my words up.  It should say Problems don't usually occur with coating acryllics with enamels.

Summary
Enamel over Acrylic: Okay, but
Acrylic over enamel: Avoid, but sometimes works with certain combinations of paints.

[Barry Krell]

I've used an acrylic varnish over enamels in the past with few problems.  I'm no chemist but I think that the problem is that the enamel coat hasn't fully dried, it's still outgassing and that causes some reaction with the enamels.  Best to leave the project to fully dry for a week or so. Remember some people had problems with Xtracolour enamel not fully drying for up to a year (!) or so in some cases.