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I've been having a bit of trouble with my airbrush and one of the possible sources of troubles may be grain size in the paints, this got me thinking...

Have anyone done a study on the ACTUAL size of grains in different paints? I was thinking that maybe you could use a microscope to measure (yes, I am crazy)

 granander wrote:
I've been having a bit of trouble with my airbrush and one of the possible sources of troubles may be grain size in the paints, this got me thinking...

Have anyone done a study on the ACTUAL size of grains in different paints? I was thinking that maybe you could use a microscope to measure (yes, I am crazy)

I've never seen such a write up if anyone has actually done it. From my personal experience, Vallejo Air has never been a problem in my airbrush, P3 paints have never been an issue when they've been thinned down a bit, and I've also shot Badger Airbrush paints and Tamyia and never had a problem.

I have had problems with GW, Reaper, and a couple other brands- mostly non-aribrush friendly. It makes me think that airbrush paints just have a very, very fine pigment particulate compared to non-airbrush paints. You can see this when you look at a GW Gold and actually see the pigment flakes, and compare it to Vallejo Airbrush Gold and not see any flakes (with the naked eye anyways).

One thing that helped out a lot using GW paint- strain the paint before it goes into your airbrush. Here is where it gets funky. Use nylon stockings. Either pour the paint through the nylon into another paint pot, then pour that paint into the airbrush, or set up the nylon over the cap of your airbrush and pour the paint that way. Needless to say, this is an incredibly tedious, time consuming, messy operation. It does work! The size of the paint clumps you will get on your nylon will amaze you. I just tend to avoid GW and Reaper in my airbrush, and if I do use them, I use a lot of Vallejo Airbrush Thinner. From what I understand, the thinner breaks down the bonds between the pigment and medium making the paint... thinner. Flow Improver (or medium) thins the paint by adding more liquid medium into the paint and retards the drying time a little bit to help prevent dry tip or clogs. Experience and trail and error are about the best advice I can give you when it comes to "Which should I use?"

 granander wrote:
I've been having a bit of trouble with my airbrush and one of the possible sources of troubles may be grain size in the paints, this got me thinking...

Have anyone done a study on the ACTUAL size of grains in different paints? I was thinking that maybe you could use a microscope to measure (yes, I am crazy)

What paint specifically? I haven't had too many problems with any hobby related paints and I've tried a lot of different brands.

As for pigment size, any study would be difficult because you'd have to test almost every paint in a given range because even within a given range there will be variability from one colour to the next depending on what material was used for the pigment. I think pigment grains are typically in the 0.1 to 1+ microns.

AllSeeingSkink wrote:

 granander wrote:
I've been having a bit of trouble with my airbrush and one of the possible sources of troubles may be grain size in the paints, this got me thinking...

Have anyone done a study on the ACTUAL size of grains in different paints? I was thinking that maybe you could use a microscope to measure (yes, I am crazy)

What paint specifically? I haven't had too many problems with any hobby related paints and I've tried a lot of different brands.

As for pigment size, any study would be difficult because you'd have to test almost every paint in a given range because even within a given range there will be variability from one colour to the next depending on what material was used for the pigment. I think pigment grains are typically in the 0.1 to 1+ microns.

In this particular case it was Vallejo Game Color (not air) Dark Green and Bone White (yes I play Dark Angels) First I used a .15 needle and now I use a .20 needle. The thing is that Vallejo says a .30 needle is recommended so I can't really fault them... but I really want to use a finer needle to do detail work. I will be ordering the same paints from the Air range and try if there is a difference.

Nozzle size isn't the main driver of how detailed you can paint, needle geometry and air cap size drive how fine you can paint.

Generally a longer needle with more gradual taper will produce finer lines, regardless of the nozzle size. It just happens to be that super long needles are usually included with the smaller nozzles.

What sort of thinner are you using? I've found that makes a big difference in my ability to paint fine lines. When spraying water based acrylics I've found Vallejo Airbrush Thinner is good, but mixing in a touch of flow improver and also a touch of Vallejo Airbrush Cleaner helps. It may be counter intuitive but maybe a hint of drying retarder might help as well to stave off paint drying on the tip, letting you run a lower pressure and get closer to the model. I always found tip dry to be my main enemy when trying to paint fine details with an airbrush and when I went down a nozzle size and to a longer needle I found realistically I couldn't spray as fine details because with regular acrylic paint I'd get build up on the needle in a matter of seconds.

Last time I was trying to paint super fine lines I swapped to Testors enamels primarily because of the extra control they afforded, but it depends on the specific colour, for whatever reason Testors dark green was superior to any acrylic dark green I tried, but I just can't get one of the Testors RLM greys to spray without spluttering.

This is partly why I end up with 5 versions of the same colour from different brands, trying to figure out which one will spray the nicest Pigment grain size is only one of the factors so even if someone went to the monumental effort of categorising every colour of every brand of paint, it's still no guarantee you'll get the easiest one to spray from a fine nozzle.

FYI, I bent my 0,2mm needle ages ago and never bothered to get it replaced because even before I bent it, it hardly got used, more trouble than it was worth and I found I could spray just as fine details with my 0.3mm needle/nozzle.