# Airbrush causing grainy surface?



## PixelMagic (Aug 25, 2004)

Hi all. I got a new airbrush, and I just tried to use it. To my horror, as soon as I started shooting it, the paint hit the surface very grainy and dusty looking, not smooth as I would expect. Here is what I did...

1. Decanted Tamiya AS-20 Insigna White into a new bottle.

2. Let the Decanted Tamiya paint gas out for over an hour.

3. Hooked up my new Iwata Esclipse airbrush straight out of the box, I didn't adjust needles or anything. I shot the paint at 18psi. I did not thin the paint because decanted Tamiya should already be properly thinned.

The thing that I noticed most was that I had to pull the trigger on the airbrush ALL the way back to get paint to even begin to come out at all. Even at full power, the paint was barely coming out. A half-way trigger did not release paint. What am I doing wrong here?


----------



## Steve H (Feb 8, 2009)

I haven't airbrushed in years, but that step, pouring paint into a new bottle (I assume airbrush bottle, or did you pour from the new bottle into the cup?) and letting it sit for an hour to outgas.

Is that a thing? I always poured into the airbrush bottle/cup, thinned it a bit and went right to work. I never allowed time for outgassing. Isn't it the volatiles in the paint that ALLOW it to be thin enough for airbrushing?

Did you do any test shooting of water, to check if the pressure was sufficient?


----------



## barrydancer (Aug 28, 2009)

Steve H said:


> I haven't airbrushed in years, but that step, pouring paint into a new bottle (I assume airbrush bottle, or did you pour from the new bottle into the cup?) and letting it sit for an hour to outgas.
> 
> Is that a thing? I always poured into the airbrush bottle/cup, thinned it a bit and went right to work. I never allowed time for outgassing. Isn't it the volatiles in the paint that ALLOW it to be thin enough for airbrushing?
> 
> Did you do any test shooting of water, to check if the pressure was sufficient?


The rattle can propellant boils at room temperature. You let it sit until it all boils out, or outgassing, before you try to spray with it.

Here's an article from Tamiya about it.
http://www.tamiyausa.com/articles/decanting-tamiya-spray-301?category_id=8&type=article#.U8xlzrHyRGg


----------



## barrydancer (Aug 28, 2009)

PixelMagic said:


> Hi all. I got a new airbrush, and I just tried to use it. To my horror, as soon as I started shooting it, the paint hit the surface very grainy and dusty looking, not smooth as I would expect. Here is what I did...
> 
> 1. Decanted Tamiya AS-20 Insigna White into a new bottle.
> 
> ...


Could be you need to adjust the airbrush somehow? I use a Badger Patriot 105, and whenever I've had a similar problem it was because I didn't thin enough or I had a clog. 

Try some water. If it sprays that, it could be the paint. Add a couple drops of lacquer thinner and see if that helps.


----------



## PixelMagic (Aug 25, 2004)

barrydancer said:


> Could be you need to adjust the airbrush somehow? I use a Badger Patriot 105, and whenever I've had a similar problem it was because I didn't thin enough or I had a clog.
> 
> Try some water. If it sprays that, it could be the paint. Add a couple drops of lacquer thinner and see if that helps.


Ok. Another thing that concerns me is paint flow. I feel like I shouldn't have to pull the handle back all the way to get paint flow. Even at full power, the paint barely comes out in a mist and takes quite a while for build up.


----------



## Steve H (Feb 8, 2009)

barrydancer said:


> The rattle can propellant boils at room temperature. You let it sit until it all boils out, or outgassing, before you try to spray with it.
> 
> Here's an article from Tamiya about it.
> http://www.tamiyausa.com/articles/decanting-tamiya-spray-301?category_id=8&type=article#.U8xlzrHyRGg


Ah, see, I didn't understand you were taking spray paint, spraying it into a bottle, with the intent to airbrush it.

I am not a chemist but I suspect that is the root of the problem. I suspect spray paint is somewhat different from bottle paint, chemically speaking.

I note that the article referenced specifically mentions the TS line of paints. He's discussing synthetic lacquers, I *think* the AS line is an acrylic based paint.


----------



## Prologic9 (Dec 4, 2009)

I think you should spray some normal paint and see how it goes, eliminate the spray paint as an issue.


----------



## PixelMagic (Aug 25, 2004)

Prologic9 said:


> I think you should spray some normal paint and see how it goes, eliminate the spray paint as an issue.


I'll probably do that tomorrow.


----------



## b26354 (Apr 11, 2007)

I decant Tamiya spray paint all the time. My Ent C was painted with decanted insignia white and the 2 shades of blue were mixed from AS-19 Intermediate blue and Insignia white.

http://www.b26354.co.nz/Enterprise-C/

You need to put a few drops of thinner into the paint after it's finished outgassing. The AS range of Tamiya paint only seems to work with Tamiya lacquer thinner though. Auto paint thinner works with the normal TS Tamiya colours but the AS paints don't seem to like it. 

The tamiya thinner comes in a square plastic container with a yellow cap.


----------



## PixelMagic (Aug 25, 2004)

b26354 said:


> You need to put a few drops of thinner into the paint after it's finished outgassing. The AS range of Tamiya paint only seems to work with Tamiya lacquer thinner though. Auto paint thinner works with the normal TS Tamiya colours but the AS paints don't seem to like it.
> 
> The tamiya thinner comes in a square plastic container with a yellow cap.


I have the Tamiya Lacquer thinner with the yellow cap. Do you have a suggestion for thinning ratio, or how many is a "few drops"? Thank you.


----------



## starseeker (Feb 1, 2006)

Try blowing straight thinner or (much cheaper) lacquer thinner through the airbrush. If it blows through fine, then the problem is with the paint. Decanting any paint and blowing it through an airbrush is nothing that would cause a problem. However some airbrushes don't work well with modelling paints at all. They're designed for artists and artists paints, which are much finer, almost liquid. If you suspect that's a problem, try a Vallejo airbrush (not regular Vallejo) paint. They're pre-thinned and work perfectly out of the bottle. If that works, keep thinning the Tamiya until it until it blows nicely. If it doesn't blow through fine with good light coverage, the problem is with the air. For my airbrushes and paints, 18psi is a little low, not pencil but chalk line width low. I normally find that 22-28psi is nominal, depending on the paint. Too much pressure will cause the paint to dry as it leaves the airbrush, leaving a grainy surface. Also how have you adjusted the intensity itself on the airbrush? Is the needle set for a fine line or a wide spray? For a very fine line, you use a very low pressure (10-12psi) and get the tip about 1/2" away from the object. Also, did you clean the airbrush after your first attempts? If not the paint may have dried inside your airbrush and you may need to clean it (lacquer thinner) before you try anything. Use the lacquer thinner only in a very well ventilated space, same as you would for any model paint. Treat them all as toxic and you'll always be safe. Also check the hose to make sure you're getting a good airflow. Block the airbrush end with your thumb and check the rest of the hose and regulator/filter and the compressor to make sure there are no leaks anywhere. At maximum psi as much air should be coming out as going in. I do find my Iwata to the the finickiest of my four airbrushes. It has a definite learning curve. But my first guess is that the line width is set at the narrowest. The tip is too far away from the object for that fine a spray, and it's drying in the air, creating the grains.


----------



## PixelMagic (Aug 25, 2004)

starseeker said:


> But my first guess is that the line width is set at the narrowest. The tip is too far away from the object for that fine a spray, and it's drying in the air, creating the grains.


Interesting. How do I adjust line width? I don't know a whole lot about air brushes, I'm just learning. I had a Paache airbrush I used straight out of the box without adjusting anything, and it worked great. Perhaps this Iwata needs the fine line adjusted as you say.


----------



## starseeker (Feb 1, 2006)

First thing to try:
From the Iwata site: "For the Eclipse, working pressures generally vary between 20 and 60 psi, depending on what type of work is being done and what textures are desired. In general 35 psi or above is desired to take full advantage of the unique, versatile spray characteristics of the Eclipse. The viscosity of the paint and your desired spray characteristics will also effect your ideal pressure. As a general rule, larger amounts of paint, or thicker paints, will be sprayed with higher pressures." While you're doing this, check for air leaks anywhere in the system, too. Even a kinked hose will stop things up quite nicely. 

Second thing to try, if the first doesn't work: 
Spray width isn't the best way to describe it, I guess. The width is controlled by the trigger. But if the needle doesn't move far enough back, then it won't allow a wide spray. There's a locking nut on the needle, arrowed below. First make sure the locking nut is tight and that the needle moves back and forth with the trigger. If it doesn't, tighten. If it does, loosen off the locking nut and just draw the needle back slightly, then forward again, just to make sure something isn't stuck in the tip. Don't force the needle forward again or you could damage the tip. Just slide it forward gently to re-seat it, and tighten the locking nut again. 

And if all that that doesn't work, and even if it does, try a Vallejo airbrush paint (it's the right consistency for all airbrush paints, so you'll also see what that's like). 

And if nothing works, take it in to your local modeller's/artist's airbrush store and get them to give it a look. Airbrushes are great when they work, but the tiniest things can mess up their performance. The two big rules are Always keep them scrupulously clean and Never force anything, especially around the tip, especially the needle. Every airbrush works completely differently from every other airbrush. People always want to know what the best airbrush for modelling is. It's simply the one you can make work the way you want it to, regardless of style or brand.


----------



## Skymods (Feb 5, 2001)

I completely agree with starseeker. It appears the needle is not being pulled back. Check the locking nut he refers to in the photo. It may be loose.

If it is tight, maybe the needle itself is stuck. Remove the back handle, loosen the nut a see if you can remove the needle.

Dave


----------



## seaQuest (Jan 12, 2003)

Basically, what is happening is your paint is coming out too "hot" and drying at or near the tip before the compressed air sends the paint on its' way to the model surface. That results in a pebbly finish.


----------



## PixelMagic (Aug 25, 2004)

seaQuest said:


> Basically, what is happening is your paint is coming out too "hot" and drying at or near the tip before the compressed air sends the paint on its' way to the model surface. That results in a pebbly finish.


I am going to attempt to use Mr. Color paint retarder to see if this helps.



starseeker said:


> First thing to try:
> From the Iwata site: "For the Eclipse, working pressures generally vary between 20 and 60 psi, depending on what type of work is being done and what textures are desired. In general 35 psi or above is desired to take full advantage of the unique, versatile spray characteristics of the Eclipse. The viscosity of the paint and your desired spray characteristics will also effect your ideal pressure. As a general rule, larger amounts of paint, or thicker paints, will be sprayed with higher pressures." While you're doing this, check for air leaks anywhere in the system, too. Even a kinked hose will stop things up quite nicely.
> 
> Second thing to try, if the first doesn't work:
> Spray width isn't the best way to describe it, I guess. The width is controlled by the trigger. But if the needle doesn't move far enough back, then it won't allow a wide spray. There's a locking nut on the needle, arrowed below. First make sure the locking nut is tight and that the needle moves back and forth with the trigger. If it doesn't, tighten. If it does, loosen off the locking nut and just draw the needle back slightly, then forward again, just to make sure something isn't stuck in the tip. Don't force the needle forward again or you could damage the tip. Just slide it forward gently to re-seat it, and tighten the locking nut again.



I have already taken the airbrush apart and the needle seems to be good. I am suspecious of the psi however, as I am shooting at 18 psi. However, I've seen people say they shoot paint at 15-20 psi with no problems. They might be using other airbrushes though, and maybe the Eclipse requires 35.


----------



## Skymods (Feb 5, 2001)

I use an Eclipse and usually shoot at 15-20 psi with no problems.

Have you tried to spray just plain water?

Dave


----------



## RossW (Jan 12, 2000)

What are you using for your air source? A compressor?


----------



## PixelMagic (Aug 25, 2004)

RossW said:


> What are you using for your air source? A compressor?


Yes. A Iwata Ninja Compressor, which maxes out at 18 psi.


----------



## RossW (Jan 12, 2000)

Do you have a moisture trap in your PSI gauge, or if not an inline one?


----------



## PixelMagic (Aug 25, 2004)

RossW said:


> Do you have a moisture trap in your PSI gauge, or if not an inline one?


Ross, I use this...

http://www.amain.com/product_info.p...roduct-Feeds&gclid=CMH7v9qq2b8CFUYV7AodyVQArg


----------



## Skymods (Feb 5, 2001)

You never let us know if shooting plain water works. 

If the water works ok, then the problem is the paint.

If it doesn't, then the the tip of the airbrush could be clogged.

Dave


----------



## PixelMagic (Aug 25, 2004)

Skymods said:


> You never let us know if shooting plain water works.
> 
> If the water works ok, then the problem is the paint.
> 
> ...



Sorry, I did shoot water through. It was fine and worked well. I still had to pull pretty far back on the trigger before the water started coming out.


----------



## Steve H (Feb 8, 2009)

PixelMagic said:


> Sorry, I did shoot water through. It was fine and worked well. I still had to pull pretty far back on the trigger before the water started coming out.


That sounds like the needle adjustment isn't quite right still. It's like the cable on a bicycle's brakes, there's too much 'slack' to work properly.

Also, as much as I am loath to suggest spending money, it might be worthwhile to invest in a compressor that can pump out higher psi. This seems like a case of, to switch to computers for the metaphor, having RAM that technically meets the minimum standards of your OS, but the practical reality is you need much more for things to operate smoothly.

I would rather have the excess pressure ability and not use it, see. Just a thought.


----------



## PixelMagic (Aug 25, 2004)

Steve H said:


> Also, as much as I am loath to suggest spending money, it might be worthwhile to invest in a compressor that can pump out higher psi. This seems like a case of, to switch to computers for the metaphor, having RAM that technically meets the minimum standards of your OS, but the practical reality is you need much more for things to operate smoothly.
> 
> I would rather have the excess pressure ability and not use it, see. Just a thought.


I'm starting to think this too. My old compressor is about 25 years old, and it has more PSI. I'm going to get it cleaned and see how it sprays with that. If it does better, I'll probably upgrade my Iwata Ninja to something else.


----------



## PixelMagic (Aug 25, 2004)

Ok, folks, I figured out what the problem was. It was simply the decanted paint. I have decanted Tamiya glossy reds and glossy blues before with no problem and sprayed through airbrush. Apparently shooting flats are a different story. Insignia White dried as it left the airbrush and before it hit the model surface.

So what I did instead was buy Tamiya Sky Grey and Flat White acrylics in the 10ml bottles, and mix them 50/50. I then thinned that with Tamiya Lacquer Thinner (which gives the paint the durability and hardness of the spray lacquers over normal acrylic thinner) 2 parts paint, 1 part thinner. It sprayed on beautifully smooth. No grainy or dusty surface as the decanted paint did.


----------



## Skymods (Feb 5, 2001)

That's great news. I'm glad you got it figured out. I had a strong feeling it was the paint.

Dave


----------



## PixelMagic (Aug 25, 2004)

Skymods said:


> That's great news. I'm glad you got it figured out. I had a strong feeling it was the paint.
> 
> Dave


Yeah, glad that was all it was. It still confuses me why the gloss reds and blues decanted and sprayed perfectly smooth. The flat paint simply did not work at all.


----------



## Skymods (Feb 5, 2001)

Another thought,

Which Eclipse do you have? There are two needle/nozzle diameters. If yours has has the smaller/finer one, that could be another factor in how thin the paint needs to be.

Dave


----------



## PixelMagic (Aug 25, 2004)

Skymods said:


> Another thought,
> 
> Which Eclipse do you have? There are two needle/nozzle diameters. If yours has has the smaller/finer one, that could be another factor in how thin the paint needs to be.
> 
> Dave


I have this one. .35mm needle.

http://www.amazon.com/Iwata-Medea-Eclipse-Action-Airbrush-Gravity/dp/B000BQKFAI


----------



## Skymods (Feb 5, 2001)

PixelMagic said:


> I have this one. .35mm needle.
> 
> http://www.amazon.com/Iwata-Medea-Eclipse-Action-Airbrush-Gravity/dp/B000BQKFAI


Nice brush. It comes with the smaller of the two needle sizes. The other size is .5mm which is in the BCS brush

Dave


----------



## PixelMagic (Aug 25, 2004)

Skymods said:


> Nice brush. It comes with the smaller of the two needle sizes. The other size is .5mm which is in the BCS brush
> 
> Dave


So is a larger needle for covering larger areas? I eventually need to paint the surface of my 1/350th TOS, and this airbrush doesn't paint a large enough area for that methinks.


----------



## Skymods (Feb 5, 2001)

PixelMagic said:


> So is a larger needle for covering larger areas? I eventually need to paint the surface of my 1/350th TOS, and this airbrush doesn't paint a large enough area for that methinks.


That is correct, the larger .5mm needle/tip combo will put out more paint over a wider area. It's not a huge difference, but it is significant. 

I did a quick unscientific test to illustrate the difference between the tips. I sprayed Tamiya flat black XF1 mixed 50/50 with Tamiya thinner onto a piece of cardboard. The airbrush was approx. 6" away and the needle was pulled all the way back.





















I did 6 passes with the .35mm and 3 passes with the .5mm

But the good news is you don't need to buy a different airbrush if you want .5mm. All the Eclipse parts are interchangeable. You just need 3 parts, the .5mm needle, .5mm nozzle, and .5mm nozzle cap. And your good to go.









Dave


----------



## veedubb67 (Jul 11, 2003)

If you have any questions or want to order parts, contact Tom Grossman at Tag Team Hobbies.

http://www.tagteamhobbies.com/hobbyshop/airparts.html


Rob
Iwata Padawan


----------



## PixelMagic (Aug 25, 2004)

Skymods said:


> That is correct, the larger .5mm needle/tip combo will put out more paint over a wider area. It's not a huge difference, but it is significant.
> 
> I did a quick unscientific test to illustrate the difference between the tips. I sprayed Tamiya flat black XF1 mixed 50/50 with Tamiya thinner onto a piece of cardboard. The airbrush was approx. 6" away and the needle was pulled all the way back.
> 
> ...



Good to know. Thank you.


----------



## SteveR (Aug 7, 2005)

PixelMagic said:


> So what I did instead was buy Tamiya Sky Grey and Flat White acrylics in the 10ml bottles, and mix them 50/50. I then thinned that with Tamiya Lacquer Thinner (which gives the paint the durability and hardness of the spray lacquers over normal acrylic thinner) 2 parts paint, 1 part thinner. It sprayed on beautifully smooth. No grainy or dusty surface as the decanted paint did.


Thanks to all you guys for sharing the process with us -- it's good info. :thumbsup:


----------

