Tuesday, November 13, 2018

Tuesday Tips: Airbrushing Craft Paints & CHEAP Grimy Black (and other colors!)

Ever since Floquil's Polly-Scale line of acrylic paints were discontinued - and especially given the health concerns with solvent-based paints - there's been much hand-wringing about an equivalent replacement. Now, I've just started getting into the painting side of the hobby, so I fortunately don't have a lot to unlearn. But I can tell you that $4 for a half-ounce of paint is pricey no matter how good it is.

"Grimy Black" is one of those old Polly-Scale "railroad" colors that remains popular today, so this this post is going to show you how to create an "airbrush-able" Grimy Black equivalent for about $.20 cents an ounce. This'll be a quick post though since I'm totally cribbing off of Gregory M. LaRocca's excellent article in the June 2015 issue of Railroad Model Craftsman (all due credit - and much appreciation - given).

Here's the skinny. First, you'll need paint. I used Apple Barrel brand that I got from WalMart for about $.50 cents for a two-ounce bottle.

You'll also need to invest in some Liquitex products - Airbrush Medium & Flow Aid. Total cost, about $15 (but it'll last you a long time).

Mix them all together, and Voila!! airbrushable Grimy Black. Here are my notes:

And since I'm not going to leave you there, here are the details. . .

I first mixed Apple Barrel "Pavement" and Apple Barrel "White" until I got it to match the Grimy Black I had on-hand (admittedly Badger's product rather than Floquil's, but it's all the same to my eye). FWIW, the ratio of "Pavement" to "White" is about 5:1. YMMV

That's a fine, inexpensive Grimy Black paint to bristle-brush, but if you want to air-brush it, a few more steps are required.

Next - as the article suggested - I used a Sharpie to mark my paint bottle into two equal parts:

I filled the bottom half of the bottle (up to the first mark) with my craft paint (in this case, mixed for a custom color).

Then I added an equal part of Airbrush Medium to the bottle, filling to the next mark.

Finally, I added 1 ml of Flow Aid. The article suggests ".5 - 1ml" but I wanted to be certain it would flow, so I used the maximum recommended amount. (It occurred to me later that the different range may be due to different sizes of paint bottle. The bottle I used is about 5/8 oz, so 1 ml of Flow Aid is/was probably overkill).

Once that was all mixed with my powered stirrer, I set my airbrush to 20 lbs pressure, test shot on a scrap of newspaper, and started painting!

I needed two coats for complete coverage, but the first coat got it to - I'd estimate - about 85-90% coverage. The acrylic craft paints dry quickly (I think the bottle recommends only two hours between coats), but I let it dry overnight anyway.

All of the "metal" girders on the overpass in the photo above were done using this paint and method (the "concrete" was done with an old rattle can of Floquil "Concrete" from my buddy Pete - and the fumes from that are what convinced me to try acrylics!)

And that's it! Maybe it's just beginner's luck, but this worked great for me - hopefully it will for you too.

A few quick notes:

  • First and foremost - as with any acrylic paint - be sure to have a Q-tip or something with thinner on it at the ready to keep your airbrush tip clean. The main problem I had during this project was with paint flow stopping. Every time, that was due to paint which had dried at the tip clogging things up. Fortunately, a cotton swab dipped in thinner and twisted onto the tip cleaned things enough to get paint flowing again.
  • Experiment with your pressures. At one point, I went as high as 30 psi, but only because I hadn't quite figured out point 1 above (cleaning the tip). You may be able to go lower than 20 psi, but I haven't tried that yet.
  • Be careful if you shake the bottle or use a powered stirrer to mix the paint - you WILL get bubbles in the paint. I don't know if they'll be a problem (they didn't seem to be), but I'd rather they weren't there. I think next time, I'll mix the paint far in advance of when I need it, and then just gently stir it before use.
  • I was really happy with the finish I got - a nice, smooth satin sheen - but I'm not confident enough with this method to go shooting locomotives (yet).
  • Best tip of all: Practice and, if you're like me, do so on something that you can afford to mess up a little (i.e. it'll be weathered) and preferably near the back of the layout :^)
I hope you'll try out this method. And if you do, please let me know - especially if any other tips/suggestions occur to you!

(Full disclosure - after I posted this, and while looking for something else, I discovered a post I did almost exactly a year ago on airbrushing craft paint. Check it out for a different approach that uses Joe Fugate's recommended acrylic thinner with craft paint to airbrush it.)


  1. One of the best investments I've made in airbrushing with craft paints is a set of strainer funnels. AMAZING what gloppy bits you find in craft paints. Or maybe mine are just old...

    I have yet to try the flow aids. I may just have to use one of those famous %50 off coupons from the craft store. I have had good results thinning with the blue windshield washer fluid.

    1. Hey Galen and thanks for weighing in. I'm sorry it took me so long to see your comment and reply (this was right about the time we got the bad news about Rich). Where do you find the strainer funnels? I'm afraid a lot of the craft paint I have is so thick it won't even go through the strainer(!) Also, have you had any problems with gelling when using the Windex with the craft paint?

  2. Chris, using craft paint for structures I understand, but why would you use a really cheap paint on a really expensive loco? It seems to me that with the amount of Airbrush Medium and Flow Improver are only diluting the paint.
    Ralph Renzetti
    As for the window wash fluid, it depends on if it is meant for summer or winter. The summer type has amonia in it and the winter has alcohol in it. These two chemicals don’t always play well with cheap craft paint. As a result you will have to test the mixture before you paint. Window washer fluid is used as a wetting agent, so be cautious when you mix you paints.

    1. Hi Ralph and thanks so much for weighing in here! I agree - I would NOT use cheap paint on locomotives or rolling stock, especially for the primary color (though I might use it for weathering). But I've used it with success on a couple of structures/bridges. I'd also have no problem using it with scenery/weathering. As for using the Airbrush Medium and Flow Improver - my understanding from the article is that it thins the paint to make it "airbrushable" but doesn't dilute the paint or change the color. That said, I will most certainly defer to you and your experience - I'm a newbie at this and know that you've forgotten more about painting than I'll likely ever learn. Point very well taken too regarding the windshield washer fluid. I use only the formula Joe Fugate recommended in his book on painting with acrylics. I didn't know about the distinction between summer & winter types of fluid though. DEFINITELY something to keep in mind. I know that Fugate warns strongly against using alcohol, for example, with acrylics since that's a solvent and not water based (if I'm remembering his explanation accurately). No pun intended, but I tend to paint within the lines on this stuff, preferring to defer to the experience of others. :^)

  3. Here is counter statement to Joe F, don’t get me wrong, first Alcohol is not a solvent that I know of. So here is the counter, my favourite paint is Tamiya Acrylic paint, which is one of a very few paints that can be thinned with 99% Alcohol, with Tamiya 20A thinner(water based), Lacqeur thinner and also Acetone. This paint was originally designed to be a lacqeur paint but do to environmental laws in North America the lacqeur was removed.
    So going back to Joe’s statement, do you really think it’s a solvent?
    How would you like me to tell you you are drink a solvent called Scotch?
    Not all acrylics are created equal, I found out the hard way by mixing a new paint the same way I mix Tamiya, in the cup of my airbrush. A little thinner first and then some paint and stir with a brush. I set the brush aside for two seconds to pick up the model to be painted. I grabbed the airbrush and began to spray, it sputtered and then nothing, it had changed to a jello like substance. Needless to say it took 4 hours to clean my airbrush.
    The moral: test first in a pop or beer cap, but not in the brush. Lesson learned!

    1. Awesome tip about testing first Ralph! I'll definitely try to remember to do that - and to try out some Tamiya acrylics too! Sorry to take so long to reply - but really hope to be able to pick your brain some more about this.

  4. Chris there is nothing wrong with taking someone elses idea and running with it, if you're like me you'll experiment with it and tweak it and make it you're own. It's the experimenting, making mistakes and learning from that.
    When someone tells me you can't do that, I tell them, "here hold my beer". I love a challenge. I don't profess to know it all, I'm still learning myself.
    ...and yes I've probably forgotten a lot about painting but that is an age thing that I'm struggling with.
    I made a vow to myself that I would pay-it forward whenever I can to advance the hobby and the great people in it. I'm no expert but I have been around the block a couple of times. I'm just another modeler on a quest to share what I can remember.

    1. Thanks again very much for taking the time to weigh in Ralph! And as I mentioned before, I really hope I can continue to consult with you - really enjoy and respect your work - and really appreciate your taking the time to comment on the blog!