DIY Airbrush Thinner

[NiceGuyAdi]

After years of resistance, I've just ordered an airbrush for priming and basecoating (the bit of the hobby I find tedious) quickly.

My hobby space is limited and I try not to get unnecessary stuff, so before I order up a pot of dedicated airbrush thinner, thought I'd see others' mileage on making their own.

Uncle Atom of the (excellent) Tabletop Minions Youtube channel mentioned that most airbrush thinners are made up of flow aid and drying retarter, both of which I have. I'd link to the video but can't find it easily, so: pa-chachachachsssssssss.

Will a 50/50 mix of Liquitex flow-aid and drying retarder do a good job, or am I just making the learning curve steeper?

[andes]

There are several recipes floating around out there. My favorite is 70% distilled water, 30% Isopropyl alcohol (I use 90%+) and several drops of glycerin. 50/50 flow aid and drying retarder doesn't sound right to me at all.

[LameBeard]

I think CK Studios had a little video where Caleb(?) shows you get a result nearly as good as proprietary commercial thinners with a distilled water/isopropyl mix, although I think it was even more water than Andes suggests above.

[NiceGuyAdi]

Thanks both, looks like I’ve just dodged my first airbrushing headache.

[LameBeard]

This is a problem with airbrushes - there are so many variables to control. At a minimum you will usually have air pressure, air flow, paint flow, paint/thinner mix. I think as a beginner it really helps to be sure about as many as you can - otherwise the doubts just niggle away.

So you are being realistic at least - more headaches are in your future! But beautiful rewards too, no doubt. Good luck!

[NiceGuyAdi]

Cheers, next question: are airbrush medium and airbrush thinner the same thing?

My local art store I’m heading to later has Liquitex airbrush medium, and I’d rather give them the money than Jeff Bezos for the Vallejo airbrush thinner I saw online.

Edited August 21, 2022 by NiceGuyAdi
Grammar

[Arkhanist]

1 hour ago, NiceGuyAdi said:

Cheers, next question: are airbrush medium and airbrush thinner the same thing?

My local art store I’m heading to later has Liquitex airbrush medium, and I’d rather give them the money than Jeff Bezos for the Vallejo airbrush thinner I saw online.

No, but they are similar. TL;DR liquitex airbrush medium will do the job fine in most cases, and I do use it myself, though I think vallejo thinner is a bit better for my use case as I also have a bunch of vallejo paints. Some airbrush people do just use distilled water (or very soft tap water) to thin their paints, and it works for them. Personally I prefer pre-made thinner as my local water is super hard, but it's not mandatory!

Anyway, more detail.

Airbrush thinner is basically solvent, i.e. like water but more effective. It's usually either IPA or glycols (and some water). I believe vallejo airbrush thinner is glycol based. There's also a little flow aid in there, which I'll come back to.

Airbrush medium is thinner plus acrylic medium. This is the binder in acrylic paint, i.e. what makes it all stick to the model as a thin layer when the solvent dries.

If you thin paint too much with water or other solvent, the ratio of binder:solvent gets too low and it doesn't dry properly on the model; it can end up staying sticky etc. Same problem with straight thinner. Airbrush medium on the other hand, containing binder as well as solvent, so keeps the ratio up and doesn't suffer that problem - but it's a bit thicker to start with.

Vallejo airbrush thinner is designed for their paints, which are similar to GW layer paints or air paints, i.e. relatively thin to start with. So the thinner is very liquid, and you don't need as big a ratio of thinner to paint.

Liquitex airbrush medium is designed to thin their tube paints, i.e. VERY thick paints. Given they need to be thinned a huge amount to airbrush, it needs that extra binder to offset that amount of solvent so it'll still stick. For GW-style paints, you generally don't need that extra medium because you're not thinning so hard; but having it doesn't hurt anything! It's milky in the bottle, but it dries transparent, so doesn't affect the final colour.

Now, back to the flow aid. Airbrushing paint involves, surprise, blowing air over the paint on the needle to turn it into an aerosol. This causes paint to dry pretty quickly on the tip of the needle, and is called 'tip dry'. You need to remove this once it starts to clog up the airbrush, i.e. it stops spraying. You will get intimately familiar with this problem I'm afraid! Adding thinner like IPA tends to speed up drying of the paint, and thus increases tip dry, which is annoying! Flow aid, which you can also add yourself (usually only a drop or two) acts as a mild drying retarder, which offsets this. Flow aid also helps even out the paint and get it to 'flow' better and break down lumps, so is generally useful stuff. The downside is that too much flow aid will cause the paint to again cease to stick properly; IIRC, I've seen it cause beading rather than going in layers. So thinning paint with just flow aid (unless it's already airbrush ready and you're only thinning a tiny bit) is generally a bad idea, but a bit extra is very handy if paint is being an awkward sod to spray. Liquitex medium has more flow aid included than vallejo IIRC, so dries a bit slower.

So you're thinking - why not use drying retarder to prevent tip dry? Basically, it slows drying TOO well, and you'll be waiting freaking ages between layers. Since airbrushing often involves multiple thin layers to build up opacity (since the paint is so thin), having to wait so long between layers is just frustrating. But there may be circumstances where it makes sense, but personally I never use it - thinner/airbrush medium + a little flow aid has been enough for pretty much any paint, once I got the hang of it.

Finally - thinning brush paint ratios is an art, not a science. It WILL take practise to get it right, as even individual paints within a range can need more or less thinning than the next. The target is 'skimmed milk' consistency, which is vague, but you do eventually end up recognising it. I'd recommend looking for some additional guidance on thinning paint; this one is a decent start.

 

Edited August 21, 2022 by Arkhanist

[NiceGuyAdi]

I do love this forum. Super, super helpful info.

[LameBeard]

If you don’t want to give money to Bezzos, but want Vallejo, I suggest Coulsdon Models in the UK. They’ve been reasonably priced and fast sending stuff to me. Just be precise about what you are after, because Vallejo range is vast, often can confuse two similar names products. Although I say fast, I realise Royal Mail is about to go super slow so might be worth checking the courier …

I can’t say I have noticed any difference using flow aid, but I think a bit of lube on the needle helps guard against dry tip. I think that’s what the glycerin is a substitute for? But more importantly- look after that needle tip, once it’s bent, it’ll catch that paint and dry tip will be more frequent.

 

Edited August 21, 2022 by LameBeard
Typo

[Firedrake Cordova]

If it's any help, Marco Frissoni has some recipes for thinner and retarder in one of his videos.

As you've just got an airbrush, you're probably going to want to watch and bookmark this video on paint dilution (and working out what you got wrong), and Ken Schlotfeld's (owner of Badger) walkthrough. 

On 8/21/2022 at 12:22 PM, LameBeard said:

If you don’t want to give money to Bezzos, but want Vallejo, I suggest Coulsdon Models in the UK.

They were great when I used them, but I thought they stopped trading? (I can't find them)

Thankfully, there are lots of outlets for Vallejo in the UK - I've always had great service from SNM Stuff (although they're not as cheap as they used to be), and Wayland Games stock them with free postage over £20 (I know some people have had issues with Wayland, but I haven't) - a lot of the usual gaming stores also stock the range (Alchemist's Workshops, Goblin Gaming, The Outpost, etc).

Edited August 25, 2022 by Firedrake Cordova
Grammar

[LameBeard]

Looks like you are right - shame. Thanks for the tips for my next restock. Although I have found bricks and mortar stores selling Vallejo before (Frome, Reading), I thinks it’s difficult for a physical store to stock the whole range, I tend to go online to be sure of getting what I’m after.