An old argument - acrylic over enamel :)

[seadog]

One of the first things I learned in art class was - Don't.   However, When I was building models of WWI aircraft, which I usually painted in acrylics, I broke that rule occasionally. The popular varnish among modellers was Johnsons' Kleer. Never gave it a thought even put it over some wood grain effect that had been done with oils. Nothing bad happened and some of those models are now quite old. I think part of it is that the enamels were often applied with an airbrush, so the coat was very thin and dried quickly, or maybe I was very lucky. Being at the stage of bow finishing a model of a modern jet, an not really wanting to spray solvents more than I have to, I wondered. So...I made up a few test pieces. The spare drop tank was airbrushed and the two other bits were brush painted. They all received a brushed on coat of either Winsor Newton Galleria Gloss or Matt. The Matt is pretty flat, the gloss more satin, though another coat would probably go glossy.

This is my experience, and I'm not trying to start the argument all over, just thought I'd share the experiment. I think the results may have something to do with the formulation of Galeria varnish, dunno

[LotusArenco]

I don’t think there’s any real argument, just a load of self-generated old-school and internet myths regarding the use of various paint mediums. It probably stems from the use of acrylics over artists oil paints.

As an art college dropout myself, we were taught ‘thick over thin’ and ‘fat over lean’ regarding the use of oil paints. Basically allowing subsequent coats and layers of paint enough flexibility to prevent cracking and crazing. Acrylic over oil was always a no-no, mainly due to the curing times for the oils, but we did it anyway to produce wonderful arty-farty effects akin to those crackle glazes you can now buy.  

 

Enamel paints that we use for modelling are alkyd based (correct me if I’m wrong, it’s been a while since I worked in the paint industry) and much quicker to dry/cure and are usually applied in much thinner coats than oil paint. As long as they’ve been left to dry/cure long enough, I’ve never had any problem going over them with acrylics. I’ve got loads of models from years ago that I’d primed in enamel then painted with acrylic. I’ve even got some old wargame figures from the eighties that I’ve used enamel, acrylic, and then dry brushed with enamel then varnished with acrylic!

 

Enamel and acrylic users can become so polarised into separate camps that many can’t/won’t look at the advantages of either medium.  I’m predominantly an acrylic user, not because they’re better than enamel, but because of drying time convenience, and that personally I just don’t like the smell of enamels and their thinners. I’ll still happily use enamels on occasion, but these days it’s limited to making washes and occasional drybrushing in which they excel.

 

Mart

[Black Knight]

I almost always now use enamel paints as a base coat, then use acrylic over that. If a certain colour is not available in acrylic I'll use the enamel version on top of acrylic second coat

I've been brush painting acrylic on top of enamel and enamel on top of acrylic for lots of years now. Never had any problem at all.

[seadog]

Thank you chaps Didn't know that modern enamel were alkyl based. I use Liquin when I paint in oils, as it happens. The model I'm doing at the mo was done in enamel due to needing to mix the colours I needed. The local hobby shop is at t'other end of the island, pain in the butt with all the holiday traffic. I use acrylics when I can and am trying to wean myself off oils for painting as well.

[Jamie @ Sovereign Hobbies]

Yep all myth. Almost.

 

Back to my old hobby-horse for a moment, the term "acrylic" has descended into meaninglessness. Water based and alcohol acrylics over enamel and vice versa is absolutely fine providing the one underneath is properly dried / cured.

 

One should be careful however with products labelled as "acrylic" but which are actual lacquers using very hot solvents. The solvents in these may wrinkle enamels. Enamels over acrylic lacquers is fine however.

 

It's worth also mentioning that enamels can be thinned with pretty much anything hydrocarbon derived. It's possible to wrinkle undercoats when applying enamels if the thinner you thinned the enamel with is aggressive - e.g. cellulose thinner.

 

Aerosols over anything is asking for trouble. The propellants are very aggressive. There's nothing an aerosol can do that an airbrushed product doesn't do better, but if one does want to use them then be cautious of oversprayed/overpainted areas of other paints around cockpits etc - aerosols are quite capable of wrinkling most types of paints in the right conditions. It's not always obvious what those "perfect storm" conditions actually are i.e. you can be badly bitten doing this the 10th time having got away with it the previous 9.

 

 

What's the conclusion? The paint binder chemistry is virtually an irrelevance - they're just fairly amiable carrier liquids. It's the thinners and, where relevant. propellent solvents that cause most of the issues.

[seadog]

Yes. I've often used Halfords primer, but I've never been sure that the I gloss lacquer would be safe. I recall using some W&N gloss varnish, not acrylic, on enamel.l and it started picking up the well dried enamel.

[Space Ranger]

Many modelers confuse the term "acrylic" with "water soluble." An "acrylic" paint is one using acrylic (i.e., synthetic) pigments or binder. Most hobby "acrylics" are technically enamels; once cured, they cannot be reconstituted with their original solvent, unlike lacquers.

 

The confusion comes from the fact that many of the hobby "acrylics" use alcohol as a (mild) solvent, and alcohol is miscible with water. But as Jamie points out, there are also acrylic lacquers.

 

The rule I always go by is: Acrylics over Enamels over Lacquers. I've been modelling since prehistoric days when we had to refine our own petroleum solvents and grind our own pigments. and this rule has never let me down, except in the case of Pactra's Chrome Silver enamel, over which nothing could be brushed without dissolving it.

 

Don't ask me about oil paints. I don't understand them at all.

 

[seadog]

7 hours ago, Space Ranger said:

Don't ask me about oil paints. I don't understand them at all.

Simple paints: Pigment+ oil - linseed, walnut or whatever, at its most basic, which is why it can take so long to dry! The addition of a bit of alkyd resin helps.

[Jamie @ Sovereign Hobbies]

@Stew Dapple is now fully trained in the manufacture of oil paints from raw ingredients. Like me, he probably doesn't see a huge market for them as base coats at least 😂

[Stew Dapple]

18 minutes ago, Jamie @ Sovereign Hobbies said:

Like me, he probably doesn't see a huge market for them as base coats at least

 

I don't know; the Carbon Black in particular proved to be very hardwearing when it got under my nails; took me about a week to get it all out  

 

Cheers,

 

Stew

[seadog]

1 hour ago, Stew Dapple said:

I don't know; the Carbon Black in particular proved to be very hardwearing when it got under my nails; took me about a week to get it all out

Yep,

good stuff at the dinner table...

[Space Ranger]

9 hours ago, seadog said:

Simple paints: Pigment+ oil - linseed, walnut or whatever, at its most basic, which is why it can take so long to dry! The addition of a bit of alkyd resin helps.

One of the first models I ever tried to paint was Monogram's 1/48 Douglas Dauntless, following its initial release (which tells you how long I've been in this hobby), using some left-over oil paints from a summer out-of-school paint-by-number keep-the-kid-occupied marathon. I lost that model years ago, but wherever it is, I'm sure that paint is still not dry.

[LotusArenco]

9 hours ago, Stew Dapple said:

Carbon Black in particular proved to be very hardwearing when it got under my nails

Eewww! That brings back some messy memories.

If I remember correctly one of the blues (phthalo or Prussian) was particularly stainy, which led to a rather hilarious moment when one of the lads secreted a small dollop of it behind the managers’ door handle.

 

Mart

[seadog]

Pthalocyanin blue is just plain evil. Really difficult to use in a painting without it taking over.