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Can't get rid of pebbly orange peel surface airbrushing Tamiya acrylics


ianc911
04-15-2013, 04:50 PM
Hi folks,

I'm having terrible troubles just lately trying to get even a semi-smooth coat with my airbrush. I've got an Iwata Revolution CR and I spray Tamiya acrylics and Testor's acrylic clear exclusively (X-22 sucks...).

In the past I've had no issues with this set up as long as the paint was thinned sufficiently, but I've tried to spray a gloss white and purple\blue mix recently and could not get a smooth finish for the life of me.

I'm spraying at 20 PSI, but I've tried from 15-25 PSI as well; it seemed to get worse the higher the pressure. I'm thinning the paint about 50\50 with Tamiya X-20 thinner such that it seems right to me, although I've tried varying the ratio such that the paint is so thin that it kind of fish-eyes when sprayed, to clearly too thick.

I'm holding the airbrush perhaps 4" away from the surface. Below is what a light coat looked like on one of my test strips recently. I tried everything mentioned above to improve the finish, but wasn't too successful. By really flooding the surface with paint, it seems to be wet enough to level a little better than this, but the result is still not acceptable and will require sanding.

http://cdn1.share.slickpic.com/u/IanCampbell/FisherMartini917L31970LeMans/org/IMG_0805/web.jpg

About the only thing I can think of is that it's been rather dry here lately, with the barometer reading about 35-50% humidity. Should that cause a problem like this?

I've also had problems with cracks in my Testors acrylic gloss lately as well.

Any ideas on what might be causing this? It's really killing me... Thanks,

ianc

MidMazar
04-15-2013, 11:01 PM
I don't think its a humidity issue. That is actually a decent range to spray in.
Usually high humidity will cause problems. I think its your ratio that is the issue.
Also try spraying a little farther like 5-6 inches. Not a airbrush pro, but im sure
More vets will shine in on your issue.

PS Orange peel usually is caused with either a bad ratio mix or spraying too far away.
Since you stated that you sprayed at 4 inches then thats also why im leaning on a bad
Ratio. Try thinning the paint (clear) down a bit more.

Are all the paints acrylics?

thijs37
04-16-2013, 02:52 AM
Your might want to thin your paint a bit more and spray a bit closer to the surface...Take a look at some youtube films about spray painting a real car....Spray painting a Modelkit is similar only scaled down! if you watch a painter you can see the line he is spraying, then he overlaps etc etc you can see the paint smooth out, it settles on the surface....this settle-ling is not happening looking at your picture...so either: paint too thick (paint wont settle), pressure too low(your not getting a fine mist but droplets), not close enough to surface(paint will dry before getting to the surface).....my best guess is thinning your paint a bit more! Sorry for this long explanation Hope it will help!!

thijs37
04-16-2013, 03:04 AM
By the way....I dont like the Tamiya Acrylic paints (fine for a brush...not for spraying....Not for me anyway!) You cant just use water to thin the paint for airbrushing, You need the Thinner of Tamiya

mattbacon
04-16-2013, 05:15 AM
Is it warm as well as low humidity? Your paint looks like it might be drying, or at least gelling, before it hits the surface. In my experience, Tamiya Acrylics gel quickly enough while brush painting to "clot" if you paint a second layer where you've painted previously. I think they are pretty unforgiving paints, if I'm honest...

bestest,
M.

sjelic
04-16-2013, 07:35 AM
Is your AB clean, it looks to me that it is not mixing air and paint good enough and paint is not atomized in the right way. Clean the airbrush fully and try again, I am almost 100% sure this is your problem. Good test for this is to put some water in AB, put full pressure and you should get cloud of water coming out of AB (not straight flow), if you get something like miniwash (for washing cars) then AB is not clean.

ianc911
04-16-2013, 11:06 AM
Thanks for the advice guys.

I made the rookie mistake when first starting out of not thinning the paint enough, but I've had good results for the past year and a half or so and I think I know how much to thin it out now. It's just that what has worked in the past is not working now, so something's changed. Believe me, I've thinned the paint out so much that it fish-eyes when a light coat is sprayed on.

I'm only spraying Tamiya acrylics, and using only X-20A thinner with it.

The temp is not that warm actually; 65-75 F.

I spray water through the brush to clean it afterwards and am getting a good cloudy spray, ie. it appears well atomized and not a jet or stream. I'll try cleaning the nozzle out thoroughly I guess since I haven't really done that (just sprayed water through it), but everything else is pretty clean; I clean the brush after each use.

Thanks again,

ianc

stevenoble
04-16-2013, 11:39 AM
My advice may be a bit harsh, but I would ditch them and move over to either Zero paints, Mr Color (lacquer) or Tamiya TS, decanted and airbrushed. You just cannot beat those three for any body parts painting in my opinion. I've tried with Tamiya acrylics, many times and came to the conclusion that they are junk. No amount of tinkering with air pressure, thinner, thinning ratio, distance, etc, ever produced a nice finish for me. I still use the matt and semi-gloss finishes though as they do spray relatively well.
You mentioned that your clear has cracked lately as well..?? If you're clearing over the top of the Tamiya acrylics I would assume that the cracks are appearing in the clear because the Tamiya acrylics take an age to dry. When you've cleared them they were not dry properly and the paint has then continued to dry under the clear and that shrinkage has caused the clear to crack.

Exotics_Builder
04-16-2013, 12:24 PM
By the way....I dont like the Tamiya Acrylic paints (fine for a brush...not for spraying....Not for me anyway!) You cant just use water to thin the paint for airbrushing, You need the Thinner of Tamiya

You can also use rubbing alcohol. Preferrably the 90% solution to thin Tamiya acryllics.

ianc911
04-16-2013, 02:55 PM
Hi Steve,

I think I may be inclined to agree with you on the Tamiya gloss paints. They are quite difficult to thin properly and take a helluva long time to dry. They can also be quite difficult if colors are mixed I've found, getting gloppy and drying too quickly in some cases. The above pic is a mix unfortunately, but I had to mix to get the Hippy 917's 'Burple' color...

I initially suspected the gloss cracking was due to inadequate drying, but I still got it after leaving a body to dry for a week. I also suspected some kind of surface contamination, but perhaps a week is just not long enough?

The trouble is that I absolutely don't want to spray anything but acrylic paints due to the toxicity factor; it's just too much of a pain. I've tried the Testors acryl paints one time and they seemed fairly junky as well. Haven't tried anything else though. I think my LHS carries Gunze; maybe they're worth a shot? Another solution might be just to paint bodies with the Tamiya flat colors, then gloss or semi-gloss over the top of them when they've dried...

ianc

stevenoble
04-16-2013, 04:38 PM
The trouble is that I absolutely don't want to spray anything but acrylic paints due to the toxicity factor; it's just too much of a pain. I think my LHS carries Gunze; maybe they're worth a shot?

ianc

You're pretty limited if you only want to use pure acrylics. I'm lucky in that I have a proper extractor fan that removes all the fumes from my workspace, so I have no toxicity issues. The Gunze paints are really good, but the ones I'm talking about are the lacquers (Mr Color) which are a bit smelly like Tamiya TS in a jar is how I'd best describe them.

Diccy
04-16-2013, 05:51 PM
I have been spraying acrylic's for years now, and i can tell you that you really need to thim pretty heavely.
I thin them usually around 30 to 50%, so on 10ml paint i add about 3 to 5 ml Isopropanol alcohol (aka rubbing alcohol) and with clearcoating somethimes i go up to 100% but with a bit more distance and quicker speed.
I know it sounds like very much thinning, but the alcohol evaporates very quick, and even quicker when atomised by airbrush, so by increasing the thinning you can lay down a wet-coat that even dries in minutes.
But like with most of things, a lot of practice and some experimentation:naughty:

Some_Kid
04-16-2013, 11:27 PM
Tamiya acrylics are really good but you need to use their thinner, but you can also use alcohol. Primarily though I like Tamiya acrylic metallics. Gold, metallic grey, x-11 and flat aluminum for engines and metal parts, those are really good paints. For interiors I actually like to use testors acrylics, in the large bottles. You can easily use alcohol with those and they dry smooth and semi glossy which is nice for interiors. Testors semi gloss black acrylic is very good as a brush paint too.

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