Acrylics and Airbrushes

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Acrylics and Airbrushes

Postby martin » Mon Nov 09, 2009 2:33 pm

I tried using acrylics with my airbrush today with disastrous results.

To begin with I thinned the acrylic way too much, then it seemed not enough as the paint spat all over my model.

Thinking my airbrush was dirty or damaged i took it to pieces and cleaned it, put it back together and tried again - same result. Tired a different mix and not much better... should it be this hard? Enamels seem so much easier!
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Postby gfadvance » Mon Nov 09, 2009 3:32 pm

Martin, what brand of acrylics are you using?
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Postby andrew milner » Mon Nov 09, 2009 3:59 pm

and what are you using to thin them?
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Postby martin » Mon Nov 09, 2009 4:33 pm

Hi gang,

I'm using Humbrol acrylics.

To thin I've tried a water/airbrush cleaner solution

And water/windscreen solution

I got good results with the latter for a while then a blockage. Really odd because the acrylics themselves have a really good consistency
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Postby underworld » Mon Nov 09, 2009 4:41 pm

Martin

Possibly there are specifications for thinning
from the manufacturer of your airbrush. I have
an HVLP gun and there is a maximum amount
to thin of 10%.....probably much different than
a standard airbrush though.


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Postby michael » Mon Nov 09, 2009 5:35 pm

Hi Martin; What sort of compressor are you using, and is there a drier on the air, sometimes during the action of compressing air a build up of moisture occures in the tank, which if not removed can migrate down the line and create exactly the sort of condition you describe. I can't help on the paint though.
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Postby gfadvance » Mon Nov 09, 2009 6:45 pm

Martin,

I have not airbrushed with Humbrol acrylics, but have used the new rev ell ones which I believe are very similar. I noticed with these that plain distilled water seemed to be the best ...... they did not seem to like the addition of windscreen washer fluid.

I also had to play around with the air pressure and ended up using them at between 12 and 15lbs pressure ... sorry can't remember the "bar" conversion.

Sorry probably not a lot of help :cry:
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Postby jacko » Mon Nov 09, 2009 8:10 pm

hi 1 bar = 14.2 psi 8) or 1 bar = lots of silly people :lol:
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Postby gfadvance » Mon Nov 09, 2009 8:43 pm

Martin,

is my memory playing tricks ... was you that doing a circular pizza layout with a superb carved plaster wall ? if was did you ever finish it?
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Postby martin » Mon Nov 09, 2009 9:16 pm

gfadvance wrote:Martin,

is my memory playing tricks ... was you that doing a circular pizza layout with a superb carved plaster wall ? if was did you ever finish it?


Yes that's me

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I've also been horribly busy with work and stuff..

However this weekend I started to lay my own track with help from my good old Dad, hopefully by next weekend i'll have some more photos to share!
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Postby martin » Mon Nov 09, 2009 9:20 pm

Micheal : Compressor : just a Tabletop Revell (limited to 20 mins of air time)

I'm going to try this on a more advanced compressor and airbrush, last time I used enamals (two months ago) all was fine.

GFADVANCE : I do have some Revell ones, i'll give them a go, might also give plain distilled water a go.

I did some more on a test piece and its dried in a really strange way, slightly matted with a slight minute "crystalised" texture to it.

thanks for all the help, support, suggestions!
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Postby gfadvance » Mon Nov 09, 2009 10:11 pm

martin wrote:I did some more on a test piece and its dried in a really strange way, slightly matted with a slight minute "crystalised" texture to it.


That sounds like you are either spraying too far away from surface... paint is dry before it hits surface, or moving air brush too quickly again paint is drying before it can flow together .

Or, and this could link to your clogging problem you haven't thinned paint enough - again would lead to a dry crystallised surface texture.

I always aim to thin paint to at least skimmed milk like viscosity - if its too thin as long as you don't spray too thickly it won't run at worst you may have to give a few coats to build up the colour but at least it shouldn't clog the air brush.

Appreciate these answers give a number of options but using an airbrush is always about practice and more practice and then if you change to different paints even more practice ( I always keep a couple of scrap kits to try out on every time before spraying the model I am working on)
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Postby martin » Mon Nov 09, 2009 10:23 pm

Hi Gordon,

I think its a combination of trying a new medium and some kind of fault. Last time I tried it it started to cut out as if clogged...

I'm going to get my enamels out and give them a go, as I know its something I can satisfactorily use. It will also help to see if there is something wrong with the brush or compressor

Thanks!
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Postby Anonymous » Mon Nov 09, 2009 10:50 pm

Acrylics are very sensitive to pressure. I often use only 8 or 10 pounds when I shoot Tamiya brand paints. I tend to use them straight from the bottle with minimal thinning. I also use their branded thinner and not any other solutions.

Hope this helps.

Chris
Last edited by Anonymous on Tue Nov 10, 2009 4:21 am, edited 1 time in total.

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Postby eje655 » Mon Nov 09, 2009 11:30 pm

I don't know if they have ModelFlex brand over there, but those typically don't need to be thinned. But I think overall, it's probably a little more tricky to get water-based to work well. They're a little easier to clean up, but it makes some other things more difficult. I've found that they do start drying in mid air more easily than solvent based, which is what gives that matte look. Less pressure and maybe trying to clean the tip more often might help. As you know, the paint is harder to get off once it does dry with water-based, so you have to be more careful.
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Postby martin » Mon Nov 09, 2009 11:42 pm

twofoot wrote:Acrylics are very sensitive to pressure. I often use only 8 or pounds when I shoot Tamiya brand paints. I tend to use them straight from the bottle with minimal thinning. I also use their branded thinner and not any other solutions.

Hope this helps.

Chris


Thanks,

I'll look to see if there is a humbrol thinner

eje655 wrote:I don't know if they have ModelFlex brand over there, but those typically don't need to be thinned. But I think overall, it's probably a little more tricky to get water-based to work well. They're a little easier to clean up, but it makes some other things more difficult. I've found that they do start drying in mid air more easily than solvent based, which is what gives that matte look. Less pressure and maybe trying to clean the tip more often might help. As you know, the paint is harder to get off once it does dry with water-based, so you have to be more careful.


Not heard of ModelFlex but i'll do a quick google! I think i'm realising it *is* much harder with water based paints, fortunately I've not bought too many of them!

Many thanks
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Postby martin » Mon Nov 09, 2009 11:44 pm

well i've finished soaking the brush parts after my last attempt three or so hours ago... I always clean then soak.. but I was really suprised to see the amount of tiny flecks of paint the cleaning had missed... the acrylic is obviously forming clumps in the brush.

Had a go with enamels just to test the brush and all seems to be working well.

Back to enamels then (fortunately I have plenty of them!)
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Postby Adrian » Mon Nov 09, 2009 11:45 pm

G'day all

The local expert uses Tamiya acrylics and thins with methylated spirits.

While having not yet tried spraying anthing myself, having seen his work I can say that is comes out really well.

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Postby michael » Tue Nov 10, 2009 1:33 am

When I was building architectural models commercially I used to use some household paints often acrylic and always thened them with lacquer thinner, yes I did say lacquer thinner. I have also thinned Humbrol enamels with lacquer thinner. I know that normally one cannot pray lacquers over enamels but when using as a mix it worked well and dried faster as well.
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Postby Willow Creek Traction » Tue Nov 10, 2009 3:39 am

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Postby Granitechops » Tue Nov 10, 2009 9:17 am

michael wrote:When I was building architectural models commercially I used to use some household paints often acrylic and always thened them with lacquer thinner, yes I did say lacquer thinner. I have also thinned Humbrol enamels with lacquer thinner. I know that normally one cannot pray lacquers over enamels but when using as a mix it worked well and dried faster as well.


that just reminded me
I once had a problem brushing acrylic onto cheap figures, it tended to easily scratch off

so as an experiment
I mixed some acrylic with some varnish,
it painted on very smoothly & was very scratch resistant
to be honest I expected it to 'curdle' or otherwise react

the figures have survived 3 -4 years rough & tumble in the garden very well

I realise that doesnt help with Martins situation

but often experimenting does yield unexpected results
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Postby scott b » Tue Nov 10, 2009 12:38 pm

I recently have brought out my airbrush again to once again try and make it do my bidding but as with every time but the firs,t terrible results. This time I went and bought createx airbrush paint and still no matter how I set up everything, it will paint fine so I think great now I will get the model and as soon as I try to paint the model splats and blobs. The first time I used it amazing results I thought this is the best thing since sliced bread, took it down cleaned it thoroughly even the second time wonderful finish but every time since terrible to the point ebay is looking good. So I understand the frustration of the airbrush.
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Postby Steve Bennett » Tue Nov 10, 2009 1:18 pm

As a big fan of Humbrol Acrylics, I guess I had better chip in :lol:
They do take a bit of getting used to, but do give the hardest finish of any acrylic I know of, so they are my preferred choice for loco's and stock.

From reading this thread, I suspect that there are a number of contributing factors to your problems Martin.
First off, they are completely different to Humbrols enamels and need to be treated differently. Mainly the way the paint atomises in the airbrush, the particles are a lot more dense and require more thinning and higher air pressure.

As a guide only this is what I use:-
Thinning 50/50 with screenwash
60 PSI minimum air pressure
Apply thin coats. Too much paint flow will collect on the airbrush nozzle and cause splatters, I suspect this is your main problem.

Every paint has it's own characteristics and takes time to learn how to get the best results from it. Keep experimenting :wink:
Last edited by Steve Bennett on Tue Nov 10, 2009 2:44 pm, edited 1 time in total.
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Postby gfadvance » Tue Nov 10, 2009 2:43 pm

Steve Bennett wrote:60 PSI minimum air pressure


flipping heck Steve never even sprayed full size cars at that pressure :!: well not completely true but you know what I mean. :lol:

Going to get myself some of this paint and try your recommendations

But at that pressure better make sure I tie the model down :wink:
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Postby michael » Tue Nov 10, 2009 2:52 pm

I would have to agree with Steve, I used to use 55 psi most of the time, when I wanted to create a flecked finish (a base of solid colour with a couple of diferent contrasting colours to simulate granite or similar textures colours) I would lower the pressure to 20 psi, and open up the paint lower the volume of air. Rarely have I used anything lower than 20psi.
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