What is the consistency of milk? (And other airbrushing questions for miniature painters)

A recent comment concerning airbrushing and miniatures triggered some pretty unpleasant memories from when I started out with the great clogging cash-eater (also known as an airbrush). As I painted mostly stand-alone miniatures the past few days I thought I might as well type a blog with some airbrushing answers I couldn’t find when I was starting out. Hell, let’s turn it into a semi-faq for when your spoken faq is spelled slightly differently (usually with paint on your face due to the umpteenth clog in your airbrush). Shall we start with the consistency of milk perhaps? 

Am I supposed to go for whole, semi-skimmed, skimmed or 1% milk? 

What is the consistency of milk?

The consistency of milk is a term that only makes sense when you no longer need to worry about it. I suspect it has been introduced into airbrushing to give people starting out a question to scream in-between the – shall we say  –  ‘cries of faq’. Facetiousness aside, when airbrushing, paint has two consistencies: too thick and too thin. If your paint is too thick, the paint won’t come out. If the paint is too thin it doesn’t dry near instantaneously on hitting the target and forms a splatter. The obvious answer for these problems is either adding a thinning medium or more paint. How much? Well mix it until it has the consistency of milk ;) I’ll take my coat and hat on the way out…

The honest answer is that airbrush paint has no one true proper consistency. It all depends on the pressure you spray at, the size of your needle/nozzle and the type of paint you spray. The only way to learn this is by doing. If you are starting out, the easiest way to get a feel for this is by using airbrush ready paints. The Vallejo Model Air and Game Air lines do quite nicely. I recommend always adding one or two drops of thinning medium (no hard and fast rule). This ensures the paint flows. 

Don't use water to thin your paints for the airbrush, try one of these instead. 

Can I thin my paints with water?

Short answer: Yes you can, but you shouldn’t.

Long answer: Paint consists of pigment and a medium to make it flow (I’m cognisant about skipping a lot of detail here). If you add water into this mix, the balance between medium and pigment is disturbed. In small quantities (say when thinning down your paints before brushing them on (as you should)) this is not really noticeable (or if you overdo it, you can see the paint go bad on your palette). In an airbrush it is very easy to get the balance wrong, especially when starting out (too thick, too thick, too thin….damn). That’s the main reason not to use water. It’s easier to use a medium to thin your paints. This offers more forgiving margins of error before you get the medium/pigment balance off.

I use Vallejo Flow Improver to thin my paints. There’s also a Vallejo Thinner that’s actually supposed to be used for this. I followed the advice by Next Level Painting to switch from thinner to flow improver (supposedly it helps prevent tip dry). I’m not sure if this is actually true, but Flow Improver works well enough for me, so why switch?. I followed an airbrush-workshop by a local pro-painter and he used Thinner. I suspect it’s a matter of taste. Both bottles cost about the same and last quite long. My advice: if you’re starting out, invest in one of these and use it. By the way: do not cheap out and buy artistic flow improver. I’ve learned the hard way it does not work the same way as airbrush flow improver. It costs less for a larger bottle, but since you can’t really use it, it is money wasted. 

My compressor needs a proper dusting some day soon.

What’s the right PSI pressure setting for my airbrush compressor?

I started pointing a clogged airbrush at models in 2010 and only learned how to airbrush with some sort of result in 2012. I followed a beginners course that year. It taught me which end to point toward miniatures, how to solve simple clogs, basic maintenance and what airbrush to buy. Interestingly the consistency of milk was glossed over that day. They gave me 20 PSI as the basic setting for a compressor (if I recall correctly). The internet says 10-40 PSI. I told this rather long anecdote to cover up the fact that I’m still not entirely sure what the proper PSI setting is.

I bought an airbrush Fine Pressure Control (FPC) valve for my Harder & Steenbeck Evolution. This is a small valve on the bottom of my pistol that allows me to regulate the airflow between 20 and 100 percent. My compressor is set to a rather high pressure level and I adjust my airflow as needed. It may sound like an advanced item to buy (it wasn’t cheap), but it makes your life a lot easier. Paint doesn’t flow? Up the pressure. Paint spiderwebs? Lower the pressure. How much pressure exactly? No clue. Sure you can turn the impractical valve on the compressor but you won’t. Why? It’s difficult to turn and the compressor is way down there on the floor.

There was a running competition between my spray out pot and my wet palette for the title 'Pit of Nurgle'. I replaced my wet palette last year, handing my spray out pot victory.

What should I do when my airbrush clogs?

Curse! (find some Dutch-flavored inspiration here)

Then try to up the pressure to spray the clog away. If this doesn’t help (it tends not to) try cleaning the tip of your needle. If this doesn’t work, place your airbrush into its stand (I assume you invested in a stand, if not: invest in a stand (i.e. a spray out pot)). With your airbrush pointing slightly down, remove the needle and clean it on a rag. Stick the needle back in and carefully clean the front of your airbrush before resuming painting. The trick to this bit is to keep your pistol pointed slightly down. Otherwise paint runs back into the needle guide making your needle stick until you go for a full on clean. A needle sticking slightly inside the needle guide will making your airbrushing life a living hell.

If at all possible, never remove the nozzle with paint still in your airbrush. Paint will run between the nozzle and the nozzle cap. I had a horrid and seemingly unsolvable case of my airbrush spraying at an odd angle. This turned out to be caused by miniscule paint fragments sticking to the hole in the nozzle cap. They got there by removing the nozzle with paint still in the cup. They had to be removed by carefully brushing around the nozzle hole (hey a new bad word to call someone!). I had to wear an Optivisor to check the results. Don’t be like me. Just say goodbye to your beautiful paint mix and clean out the cup before removing the nozzle. 

A whole bunch of Vallejo airbrush paints in a pretty rack (yes I needed a picture here and didn't have an appropriate one handy).

Why is my airbrush clogging all the time?

Because your airbrush is sentient and hates you. Don’t take it personally though, airbrushes hate everyone. Aside from that, airbrushes usually clog because paint dries on the tip of the needle. You can prevent this from happening too often by making a habit of starting any paint application by spraying air only, then calmly pulling the handle back to add paint and finishing off by spraying only air again (air-paint-air). Then you can release the trigger. By always ending with a bit of air sans paint, you spray your needle clean (most of the time) and prevent clogs.

On a side-note you should always start spraying air (while pointing away from your miniature) for another reason. Occasionally there’s still a splat of paint on your needle (it mostly get there by ignoring the ‘always end with clean air rule’). If you start spraying air with a dirty needle pointing at your work, the splat will hit it and ruin all your wonderful transitions. Because Murphy’s Fourth Law is a thing, this will happen at the least opportune time.

Also pray to whatever god motivates you while spraying metallics. The slivers that make metallic paints metallic are designed to clog airbrushes. You can alleviate this slightly by spraying at a high pressure. An 0.4 needle helps as well (but I never bother because I’m rather lazy when it comes to finding my 0.4 needle).

Promising Malal you’ll roll only sixes when fighting your next Chaos opponent is the best option to prevent clogs. Especially as the next time your airbrush clogs, you can blame yourself for not following up on your promise to Malal. If you did follow up on your promise to Malal and your airbrush still clogs, you should stop using crooked dice during games, the dice gods have influence over airbrushes as well. (And this demonstrates a fundamental rule: airbrushes always clog at some point).

Disassembling your airbrush will quickly become second nature. 

How do I clean my airbrush?

I think you can find about a million articles, books and video’s that explain how to clean your airbrush better than I can. As different brands of airbrush have differing parts, I’d look for a tutorial aimed at your setup.

For beginners I’d like to add: don’t be like me when I started out. What does that mean? You do not need to clean your entire airbrush just to change colors. You can pick between just spraying the airbrush cup out into the (aptly named) spray out pot and adding the next color, or filling the cup with water and cleaning most of the paint out between colors. Oh the time I could’ve saved… 

Looking right down in the throat of the dreaded airbrush cup. Will it regurgitate paint at me or will it come out through the nozzle?

Why are there bubbles in my cup?

Most likely because something is clogging/blocking your airbrush nozzle. Try cleaning the needle and if that doesn’t work, try cleaning the airbrush. Then clean it again, because airbrushes hate humans. If a lot of cleaning (and very carefully scraping the inside of the nozzle clean) does not help, check the rubber o-rings and seals. On my airbrush the o-ring between the nozzle cap and the pistol wears down. As it gets old, the seal goes bad and my cup starts bubbling. I keep a small supply of spare rubber o-rings handy to solve this problem.

Also make sure the witches from Mcbeth aren’t anywhere near your airbrush. The constant chants of ‘Double, double toil and trouble;. Fire burn and caldron bubble.’ Inspire your airbrush to bubble. I should try to convert McDeath to AoS someday. Perhaps on the same day I will learn not to go on an off-topic tangent while writing for my blog. 

Vallejo Metal Color is an awesome line, Scalecolor 75 has some nice colors, Vallejo Game Air is rather mediocre to be honest...

Which airbrush and compressor should I buy?

I don’t know. It depends on your budget and sense of adventure. There may not be a lot of joy in adventuring. After a couple of useless single action airbrushes (the GW one and another by Revel) I bought a Chinese knock-off double action airbrush that was so ill made, it bent the needle as it slid through the needle guide. This made my first two years of attempted airbrushing very unpleasant. I  experienced constant clogs. I spent a lot of time with paint on my face, cursing creatively while watching my projects covered in gooped up paint splatters.

Fortunately we have the best airbrush shop on the planet here in The Netherlands: AirbrushService Almere. I attended a free introductory course in airbrushing there and learned about cleaning, air-paint-air and other important details. I also bought my Harder & Steenbeck Evolution 2 in 1 there. It is a properly engineered entry-level airbrush that allows you to put different size needles in it. I like my H&S a lot and the price was ok. My advice for airbrush-starters is not to skimp on the airbrush and the compressor. And (as you are about to spend a lot of money) go to a specialty store and ask for help during the purchase. I know its old fashioned, but I paint metal toy soldiers so I recon I’m allowed to be a bit old fashioned once in a while.

As to the compressor: get one that has a pressure tank. It keeps the air-pressure at a constant level. Investing in a compressor that’s reasonably silent is a good life decision too. Especially when married or living together. When it comes to compressors you’ll quickly find out that silence comes at a premium. So your budget is an important factor.

Get cleaning brushes for your airbrush, you'll need them. Toss the nozzle scraper in the garbage, it'll most likely damage your nozzle (in my experience at least).

I’ve thrown my airbrush around the room multiple times in frustration, will it still work?

Maybe, maybe not. The most vulnerable parts in the pistol are the nozzle and the needle. You’ll need to check these for damage if you’ve vented your airbrush-rage on your pistol. The bad news is that these (especially the nozzle) tend to be the most expensive bits to replace. It is wiser (and cheaper) to keep a stress squeegee handy to alleviate airbrush-rage. Cursing helps as well.

And to think Vallejo is not sponsoring this blog...ah the pain of obscurity!

Airbrushing sounds as much fun as chewing on broken glass, why would I want to do this?

Because in between the troubleshooting airbrushing is awesome. With a bit of practice you can easily and quickly block in basic colors on your miniatures. I can’t imagine painting large creatures or vehicles without an airbrush. It takes only a little practice to get nice looking effects too. You’ll feel like a painting god after applying your first decal through a mask. And you can use for other purposes like applying varnishes when you want to try oil washing. Oh and you can blow compressed air on your static grass while its still setting in wet glue for great effect.

But even if you reject the practice of practicing (perhaps you took a most holy vow to The Lady), you can still take advantage of an airbrush. I think I’ve recouped the cost of my modest set-up multiple times simply by airbrushing primer instead of using a rattlecan. The price of one large bottle of Vallejo primer is lower than a single rattlecan and it lasts over multiple armies. I also varnish using the airbrush and the only way to get the dreaded varnish frosting with an airbrush is if you overapply it (I did that once for reasons that still befuddle me). 

I needed one more picture and found this older one of my airbrush with its smaller paint cup attached (and quite dirty).

What the hell do you know about airbrushing anyway?

Not enough by far, I just use the damn thing :). But who knows, my limited knowledge might help someone along the way. At least I spared you the consistency of milk enigma and long talks about orange-skin and spiderwebbing. You’ll find the answer to those questions – and long essays about cleaning your airbrush - without my cheeky help (just open any random book on airbrushing). If you have a different question, ask and if I know the answer I’ll share it.