"Semi-gloss black acrylic as undercoat?" Topic

I have an old collection of paints (10+ years old for some), and I want to use them up if possible before buying or opening new paints. One of them is a Tamiya brand semi-gloss black acrylic that I've been thinking of using as an undercoat to go over a brush-on gray primer. Would regular acrylics hold on to a semi-gloss acrylic?

Don't see why not.

I wouldn't. Primer is formulated for paints to key on.

I know we all have our own methods of painting miniatures, but I must ask, what's the merit of first applying a brush-on grey "primer" and then a black "undercoat"? In my world, a primer and an undercoat are the same thing.

For me, I like to use an appropriate dark color underneath the more-or-less visible colors, like hull red on German tanks or a black paint for plastic infantry miniatures. A primer is something that will provide a flat even surface that will hold paint. I would prefer to use a black spray primer, but that is not an option right now and so I use a brush-on acrylic primer. Right now that is a gray primer designed to be brushed or fed through an airbrush, but I need an undercoat on top of that. If my next layers of paint do not completely cover all nooks and crannies, then that black undercoat would suffice for providing a sense of depth and folds, something that a bright gray or white would not.

I wouldn't. Primer is formulated for paints to key on.

Um, actually:
"Because primers do not need to be engineered to have durable, finished surfaces, they can instead be engineered to have improved filling and binding properties with the material underneath."
link

@MajorB,

From the link you provided.

For this purpose, primer is designed to adhere to surfaces and to form a binding layer that is better prepared to receive the paint.

Which is all I said.

If my next layers of paint do not completely cover all nooks and crannies, then that black undercoat would suffice for providing a sense of depth and folds, something that a bright gray or white would not.

Ah, I see. I suppose that in my terminology the black would be a basecoat – more or less – but we all have our own ways of defining these things and I won't claim mine is correct.

Anyway, personally I'd be wary of using semi-gloss in that manner. Sounds to me like it could cancel out the merit of the primer. Because, surely, a good primer is supposed to bind to the material underneath and provide a good "tooth" for the paints that go on top.

I've used a spray black gloss as a base coat and it seemed ok for painting acrylic and enamel paints on. Not brilliant but ok

For this purpose, primer is designed to adhere to surfaces and to form a binding layer that is better prepared to receive the paint.

Which is all I said.

No. What you said was "Primer is formulated for paints to key on". However, what the Wikipeda article I linked said is that primer is designed to adhere to the underlying surface. It said nothing about better "keying" for subsequent paint layers. Better keying would require a primer to present a "keyed" surface (that is slightly rougher) for the paint layer. "Forming a binding layer" as quoted above refers to the binding to the material underneath not binding to the paint applied above.

Relative to the value of your time paint is cheap. I'd use the right materials for the job.

I'd go with a flat black undercoat, the trouble with gloss or semi-gloss is getting the top coats to cover evenly, particularly if you drybrush a lot (like me).

Paint seems to stick much better to flat black.

Relative to the value of your time paint is cheap. I'd use the right materials for the job.

An excellent suggestion!

I have been painting figures for well over 30 years and in all that time I have always used matt enamel as an undercoat or primer. On both metal and plastic figures. With excellent results.

Two points:

[1] The Tamiya paint may not be a good primer especially for lead – bit.ly/1vuax46

[2] If the paint is in a jar just add talc, or Tamiya Flat Base, to make it matt – bit.ly/1vuadlU

Good luck.

--
Martin Stephenson
The Waving Flag | Twitter | eBay

Where can I buy Talc? That might be a good thing to try, since I never have any use for glossy black. And the black is going over a first layer of an ancient bottle of Testors Gray Primer that I acquired who knows when.

link

Any store that sells bathroom products.

Where can I buy Talc?

A pharmacy or supermarket. You want an uncoloured and unperfumed variety. One bottle will last a lifetime if my use is anything to go by.

--
Martin Stephenson
The Waving Flag | Twitter | eBay

Are there differences in purity between baby-care talc and chemistry/artist talc? Or does it make any difference?

Yes and any perfume and colour in the former will make a difference.

--
Martin Stephenson
The Waving Flag | Twitter | eBay

I think that flat black makes a better undercoat for the reasons cited above

I undercoat with black all the time

Oh! Sorry I meant to open door 3