Hi
I've just finished my first airbrushing session using acrylics since I got back into the hobby, and the results where mixed. Up till now I have only used acrylic primers, and they have been working great both with a 0.3mm and a 0.5mm needle at approx. 1 bar.
This time I used a 0.3 mm needle at approx. 1 bar (15 psi), and I used the paint unthinned, resulting in a rather coarse/grainy finish, accompanied by continuously clogging of the needle. Thinning the paint (1/5-1/3 part thinner) didn't help much. Only when increasing the pressure to approx. 2 bar, I was able to obtain some nice lines, but I feel I have less control at this high pressure.
Do I need to dilute the paint further? I was under the impression that the AK acrylics could be sprayed right from the bottle.

Any input will be greatly appreciated.

Erik

Primers are usuaully thicker than other paints and are not usually the recommended choice if you want to get nice thin lines. The thickness is why you are getting such poor performance with a small needle. As far as I know AK acrylics can be thinned with water (best to use distilled water if you can get it) so I would say thin them and see what happens.

Thanks Karl I'll try that. I didn't try to get fine lines with the primer, just meant that I'd used it without the issues experienced with the acrylic paints.

Erik

You may want to add a couple of drops of glass cleaner to your mix. This will help improve the flow.

I mis-read the bit about the lines, my apologies! Hope either Matts advice or mine(or both!) works out for you. Let us know.

Are you using Vallejo ModelAir bud?

Hi Andy, it's ak interactive.

oops. Sorry getting my topics mixed up!

Hi again
I did some further testing using the 0.3 mm needle. The AK acrylics dissolves well in window cleaner and water. However, to reach the desired consistency, it had to be diluted at least 1:1, which seemed to ruin the adherence ability of the paint, with pooling/running as a result. So what worked for me was to use acrylic thinner/paint in a ratio of 1:1 or even more diluted with a drop of retarder, and keeping the pressure relatively high 1.5-2.0 bar. Going down to 1 bar, even at this dilution ratio, produced splatters.

Over at AK interactives forums it was mentioned that their acrylics can be thinned with Tamiya's lacquer thinner, I don't have that, but tried cellulose thinner neat and a 1:1 mixture of cellulose thinner/isopropyl alcohol, and either didn't work that well. I'm gonna try with Tamiya's thinner once I get hold on some.

Erik

Keep in mind that as water-based acrylics are reduced, it's necessary to add back in the acrylic binders to get good adhesion.

So, with the thinner (water, glass cleaner, Tamiya X-20A, etc), you should add back some acrylic matt or gloss medium.

Note that this isn't necessary with cellulose based acrylics like Tamiya's (those have their own quirks), but for true water-based paints like Vallejo, you can dilute the binders too much and the pigment will not adhere.

Vallejo's proprietary, milky-white looking thinners have the necessary additional acrylic binders, but you can also buy artist acrylic matt or gloss mediums and mix those into your reduced paints. You will find these at the same places that you find the acrylic flow enhancers / flow aides and drying retarders.

HTH

Thanks Mike
Makes sense, seems to be the standard when looking at airbrush artists videos.
/Erik

Thank you for the info. I was having the same pooling problem last night. I was trying to keep the model air paint thin to help have the black primer show through a bit. However, everything pooled and didn't cover very well.

Do you happen to know if that Vallejo airbrush thinner, the clear stuff made to thin the model color paint, has the binder in it?

Jeff

Excellent post. This is exactly the reason why I no longer airbrush Vallejo acrylics. I don't have time or patience to make them work. Tamiya acrylics always work.

Jeff, sorry for the slow reply to your question. I hadn't been following this thread so closely.

No, I don't believe that the Vallejo 71.361 (60 ml bottle) "Airbrush Thinner" has any acrylic binders in it. When I use it, I do add back a couple of drops of Vallejo's 70.524 (17 ml bottle) "Thinner Medium" (same as Vallejo 061 "Thinner" in the 32 ml bottle).

I think the airbrush thinner 71.361 is mostly water with surfactants (flow enhancers) and retarders. I use it mostly to thin Model Color paints to airbrush them like Model Air paints, but when I do, I add back about 5% by volume the 70.524 Thinner Medium to improve adhesion. I do confess that I don't actually airbrush any of the Vallejo paints very often preferring Tamiya paints for the airbrush. Sometimes, though, I do want an airbrush match for something that I'm hand brushing with Vallejo and the above method has worked well.

(I don't like the drying time - slow - and lack of overall durability with the Vallejo paints when airbrushed. On the other hand, I love the way they hand brush. Tamiya acrylic paints are actually solvent-based and not water-based so their drying time is much faster, and I believe they have much greater durability and handling properties once dried.)

Anyways, I pretty much do the same when I thin Model Color paints for hand brushing, only then I use a mixture of water and artist acrylic flow enhancers and drying retarders as then thinner while adding back about the same 5% of the Thinner Medium.

In the future, I plan on testing (and perhaps then using) regular artist acrylic matt medium as a substitute for the 70.524 Thinner Medium when hand brushing. But for now, the above is what I do to airbrush and hand brush Vallejo, and I'm pleased with the results that I'm getting.

(BTW: The artist acrylic matt mediums are also excellent adhesives for ground cover materials like static grass and ground foam on diorama and vignette bases. They will also act as a good light duty adhesive in the final assembly stages of model construction when you want to avoid glue marks, etc. The matt mediums dry dead-flat and leave no physical glue blobs, so for things like pioneer tools and stowage items, it's an excellent choice as a glue.)

HTH and happy modeling!