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New to airbrushing, Vallejo primer questions
Posted 10 February 2019 - 05:21 PM
With the recent cold and rain I thought I'd get some primer to shoot so I could keep myself and the models indoors.
I thought it would be quite easy seeing as I was doing alright trying to paint with it, but it seems like a complete different kettle of fish, it just seems to run off every where.
I washed down the model to remove any mould release agents, so I don't think that's the issue. I'm using 25ish PSI, is that too high? Seems to work well with the citadel that I'm thinning, but is that too high for specially designed airbrush paints?
Any help / tips appreciated, even if it's just to practise more!
Posted 10 February 2019 - 07:01 PM
I use around 25 psi with primer, as that gives a nice coverage and means it goes through decently unthinned. (I use stynylrez these days as I can sand it and it clogs less, but I used to use vallejo). Primer should be mostly unthinned otherwise it affects the strength of the coat later.
As a rule of thumb, if paint is spidering it's one or more of the following; pressure is too high, paint is too thin, airbrush is too close. Pressure is reasonable if you're using vallejo primer unthinned, so the remaining thing to change is pull the airbrush back from the model.
You could also try lowering the pressure some (say 20 psi) but you will get to a point where it won't spray properly as the pressure isn't high enough to 'pull' the paint off the needle at a given viscosity.
Paint sprays out in a cone from the airbrush - being further back means you get wider coverage, and the paint hitting the model has a lower pressure so will stick better. A wider coverage of course is not a problem when priming, as you want it all over anyway! If you move so far back you get 'dusting' i.e. the paint starts to dry out too much mid-air and goes on speckly, move in closer! Trigger control will also help, i.e. don't blast it all in one area but do thin coats with the trigger not fully back, moving across the model as you would with a spraycan. I prime at about 8" to 10" distance or so, estimating, and the primer goes on in much thinner coats than a spraycan (which is one of the pluses, preserves more detail!)
If your citadel paint is coming out OK at 25 PSI, then it's possibly still a bit thick for anything other than all-over base coats - my usual pressure for anything other than all-over work is more like 10-15PSI. That means I can keep the brush closer, covering a smaller area, but without spidering. To get the paint to flow out nicely from the brush at lower pressure, it usually needs to be less viscous, i.e. more diluted with thinner.
Getting the balance between pressure, paint viscosity and distance so you get paint that lays down nicely only in the area you want is one skill that you learn with airbrushing and does take a lot of practise, particularly since the paint properties varies between colours from a single maker! I still have to do test sprays on scrap paper with any given colour to make sure I've got the mix right for what I'm trying to achieve, and may tweak the PSI or dilute the paint a bit further to get there.
- LetsYouDown and HazardousWaster like this
Posted 11 February 2019 - 11:37 AM
That's some brilliant tips to take back to the table. I'll certainly try thinning the citadel paints down more. I had made my own little thinner of flow improver / water / thinners to mix 50:50 with paint so I'll try changing that up to lower the PSI and get in closer.
I'm almost losing detail at the moment where it just seems to pool in the creases, I had been using a drop or two of flow improver as well, so I'll try leaving that out and keep further away.
Glad you have also said it comes out in thinner costs, I had been getting frustrated at points where it didn't seem to be leaving a coat, then pulling right back on the trigger leaving the model then covered in runny primer!
Thanks again! I'll get back to more practising!
Posted 19 February 2019 - 02:38 PM
Once you get used to spraying things through your airbrush without spidering, I've found that about 97% of problems will come from either your paint being too thick or your airbrush not being clean enough. My tips as follows:
I've found it helpful to pull the needle out when I'm done for a session of painting, as any paint you missed cleaning out will stick to it and clog the areas between the needle and the nozzle.
Every once in a while my brushes will just start giving me lots of trouble, the only thing that works when it starts to happen is to completely disassemble the brush and soak it in your chosen cleaning solution for a few hours or overnight.
Practice taking apart and reassembling your airbrush until you can do it without thinking about it too much
I'm really bad about this but try to keep your area clean, and consider doing your airbrushing on a hard floor; as when you inevitably drop a tiny nozzle while taking your airbrush apart it is a lot easier to find if it falls on a clean non-carpeted surface.
As a general rule you can spray just about any paint through an airbrush as long as you can thin it enough; I've been successfully spraying hobby store acrylic paint through mine recently. I have a mixture of water, flow aide, and matte medium that I thin it with.
Get a compressor with a tank attached so your compressor isn't constantly running. This will preserve some of your sanity and will help the compressor last longer.
If you want to stick with airbrushing (especially if you want to do more than just miniatures with one) invest in a good compressor. To be frank, compressors marketed for airbrushing tend to be really overpriced for what you get. This compressor I am currently using is one I ordered off of Amazon by California Air Tools, the CAT -1P1060S. It weighs about 30 pounds and it says it only generates 56 db of noise when it's running (I measured closer to 60 using my phone app). It was about $100 when I bought it and after a year of consistent use I had to replace the regulator on it. I use it for miniatures, art, and tattoos at local events. It has a 1 gallon tank on it so it doesn't run constantly while you use it. It's light, portable, quiet, and much more powerful than most equivalently priced airbrush specific compressors.
Old bent needles work great to clean dry paint out of airbrushes.
The best way I've found to clean an airbrush quickly takes a bit of preparation to do. If you can paint near a water source it would be helpful. But I've found that having a bucket of water within arms reach where you can just submerge the brush and spray can be very efficient. Dump your extra paint out of the brush, wipe it down with a paper towel, submerge the entire thing and just run water through it for a minute or so.
The Codex Astartes no doubt has guidance that covers that kind of situation - long, detailed advice that would essentially boil down to "shoot the choppy ones, chop the shooty ones".
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