Lost my airbrush skills...

[Hammers]

..., which were never profound to start with. Paintjob coming out blotch and orange skin, like. I suspect my compressor has always been to weak for it's purpose but I think I've got the paint consistency right. Any tips or pointers to refresher tutorials?

[Mr. Peabody]

Sorry to hear you seem to be having compressor woes. Do you think you were using too little pressure & spraying from too far away? Was your thinner the sort that tends to dry quickly -like Tamiya? That's a good recipe for orange peel.

What sort of paint were you using & what was the thinner? How old was your paint & did it require more thinner than usual?
Thinning can be a real pain, and it can be the source of so many cool effects. Some thinners dry fast, others more slowly. Some are ideal for inks and others for paints. Incompatibilities are common, so I like to mix new combinations in a small cup first, to make sure they are stable.  I thin with Windex (the real stuff with ammonia D), Tamiya thinner, Golden Airbrush Medium or even rubbing Alcohol & water depending on the paint.
Try to always have a test-board handy to spray on before spraying any subject. I always spray a biggish square of foamboard with my primer, then on to that I spray each of my colours and protective coats as a way of being sure what will happen before I spray on my subject at each step.

Here are a couple of useful bits from the web that have helped me in the past:

From Miniatatures.de. A great article that I sometimes reread when I haven't picked up my airbrush in a few months. Some very useful information.

"Popular Myth 3: Acrylic Paint Spit

Paint spit is an indication that the paint has not been diluted properly, it’s too dry, and the air pressure sends chunks of dried paint flying out of the airbrush. Very shortly, the built-up of dried paint will clog the nozzle and the needle cowling. Acrylic thinner reduces paint spit, and it prevents clogging. Tamiya X20A acrylic thinner is ideal for paintbrush use, it mixes well with Tamiya, Pactra and most other acrylic paints, with the exception of GUNZE acrylics. The new Humbrol acrylic colours mix very well with Tamiya thinner, and they are true to the popular Humbrol enamel colour numbers."

From Craig Central. The 'Thinning Paint' article, where the use of Airbrush Medium to thin paints is promoted. I don't do this exclusively, but I do keep some on hand if I want to fix a colour mix that is not spraying well. Craig Central has some great fundamental Airbrush information.

"Acrylics cure by the linking of acrylic polymers into long molecular chains.  If too much water, washerfluid, soap, alcohol, etc. is used, the acrylic is "stretched" too far and can't form proper links.  It will typically dry too rapidly and leave a rough finish.  The airbrush medium contains acrylic polymer in order to guarantee that there is sufficient acrylic present to properly link and form a strong paint film.  If thinning with just water ,washerfluid, alcohol the odds of the paint lifting or chipping are high because unlike other additives, the acrylic polymer in the medium doesn't evaporate and thus acts like a clear paint.

So while it’s ok of course to use tiny quantities various non-bonding liquids for thinner, it’s just as important to regain strength, flow and sprayability with some airbrush medium.  It’s somewhat expensive but a bottle goes a long way.

I use Liquitex airbrush medium, since it is readily available at Hobby Lobby.  It has finally made using alternatives like thick craft paints a reality for me with excellent sprayability.  And leaves a smooth texture."

Hope these help you find an answer,
TR

[Hammers]

Thank you, Peabody.

Since I am spraying quite a few pieces uniformly I use W&N artists acrylics dillluted with plain tap water. I considered using flow improver but have heard elsewhere that it should not make much difference.

I've also heard that Tamiya primer turns certain other acrylic brands to glue (Vallejo) so I am unwilling to mix it with other than  Tamiya colours.

[Mr. Peabody]

Ah. You definitely want to consider using an acrylic airbrush medium to prepare a tube acrylic paint like that for spraying. Too much water will simply break the paint and introduce surface tension problems, leading to inconsistent results.

Here is what you are looking for:
Take a moment to check out this page from Golden Acrylics and especially This Video "Thinning Heavy Body Acrylics for Spraying" which covers exactly what you want to do with the W&N acrylics. Notice the mention of 'reticulation' as a result of thinning only with water, this is perhaps the culprit causing your orange peel or net-like texture.

You can use any brand of airbrush medium, I like Golden, but there are plenty to choose from! From that point, if you like, you can adjust drying time with the addition of 'hotter' thinners like Tamiya or Windex, providing the paint is compatible. Generally I find most paints will work with one or the other.

I think we are closer to the answer now!
All the best,
TR

[DFlynSqrl]

Mr. Peabody is the airbrush king!  Helped me get my start into that particular part of the hobby.

[Hammers]

I am much obliged and bow to your superior knowledge. I shall take your advice to heart and will also consider tidy this thread up for a sticky in "How to..."

[Antenociti]

Also bear in mind that whenever you thin with water you are reducing the "stickyiness" of the paint.

That's why thinning with medium helps prevent peeling as it retains the amount of "glue" in the mixture (the medium is the bit with the "glue" in it).

When you thin from artists (tube) acrylics this is especially important as there is very little (comparitively) medium in them in the first place, so thinning with water leaves you with a double-whammy problem.