Beginner Airbrusher Needs Help

[VegasAWACER13]

Hi! I'm new here and recently returned to model aircraft building after a thirty-year hiatus. I'm also learning to use an airbrush. I'm on my second kit with an airbrush and things were going fine until I tried doing some basic detail work (mottling pattern on the side of a 1/48 WW2 fighter). I keep getting spidering/splattering on the paint. I understand this can be a problem when the paint is too thin or the air pressure isn't correct. But it seems to happen no matter what I do with the paint, including not thinning it at all, or increasing/decreasing the air pressure. The picture shows the problem. I'm using a Gaahleri 98D with a .38 needle and used 15psi with maybe 30% thinner. Tip of the brush was held maybe half a centimeter from the paper and the spots depicted are 2-3mm across. I'm also using an entry-level Gaahleri Serenair mini compressor. I've tried using minimal paint flow with a very light touch and it's not helping. I thought at first it was the result of moisture in the line but it's also occurring with a dry airbrush I've just started up. I was previously able to get runs of relatively clean mottle patterns before moisture started building up, but now I can't seem to do it at all without the spidering. I've tried taking the airbrush apart and cleaning it and have checked everything is properly tightened.

I'm at a loss for ideas at this point and at a standstill. I'm in a very humid area so I don't know if that has anything to do with. I looked at some videos on YouTube but all the basic fixes they mentioned don't seem to work. I'm guessing it's some form of user error as I'm still trying to get the airbrushing thing figured out.

I could really use some help. Thanks in advance!

 

[Jakko]

If you suspect moisture is the problem, then I have to ask: do you have a moisture trap between the compressor and the airbrush? They usually look like a glass jar hanging from a metal fixture that the air line comes out of.

 

[urumomo]

before going into more detailed trouble shooting ,
carefully examine the very tip of the needle , under bright light and magnifier , to ensure it isn't bent . It doesn't take much of a little hook on the end .

 

[urumomo]

This thing ?
https://www.gaahleri.com/products/g...pIBpWwOUJbHVqT6eNFp5GWTA7IcuwGtM915MouczR0Dty
tankled compressors are better .
those tiny , inline moisture traps are crap . too little capacity .
install a larger inline moisture trap , kinetic or , pref and , desiccant type .

 

[urumomo]

what does this mean ? : occurring with a dry airbrush I've just started up

. I keep getting spidering/splattering on the paint. I understand this can be a problem when the paint is too thin
usually the opposite . The paint is too viscous and starts building up on the needle and it's pushed out in drops when it reaches critical mass . Especially with lower air pressure .

 

[VegasAWACER13]

This thing ?
https://www.gaahleri.com/products/g...pIBpWwOUJbHVqT6eNFp5GWTA7IcuwGtM915MouczR0Dty
tankled compressors are better .
those tiny , inline moisture traps are crap . too little capacity .
install a larger inline moisture trap , kinetic or , pref and , desiccant type .

Yes, that's the one. I do plan to upgrade to a better compressor. But as I'm just starting out with airbrushing, I didn't want to get a bunch of expensive kit until I'd learned the basics and the common issues, as it seems I'm doing now. I'm just trying to determine if the problem I'm having is the result of error on my part, or if it is indeed the result of faulty equipment. The stuff I looked at indicated that the Gaahleri 98D is a quality beginner brush, and up until now, it's been performing as I need it to, with the exception of some issues with moisture build up causing it to occasionally spit water. With the basic painting and camouflage on the kit I'm doing now, everything was going well. Then I got to doing some basic mottling to finish up the paint job and ran into a brick wall with this problem. I know this mini compressor is on the cheap side, so I've been wondering if that could be the issue. But I don't want to spend a bunch of money without determining what the problem is first. I've read about people having similar issues with pricey kit.

 

[VegasAWACER13]

what does this mean ? : occurring with a dry airbrush I've just started up

. I keep getting spidering/splattering on the paint. I understand this can be a problem when the paint is too thin
usually the opposite . The paint is too viscous and starts building up on the needle and it's pushed out in drops when it reaches critical mass . Especially with lower air pressure .

I'll take your word for it. I was a very decent modeler a few decades back but I'm a pure rookie at airbrushing. The videos I looked at all indicated the spattering is generally the result of paint that's too thin. I've experimented with mixtures from 50% thinner to no thinner, and 15-28psi, and nothing has so far corrected the problem. As I indicated in my OP, I did previously get it to perform as needed, but now I'm having no luck at all. Which makes me wonder if there is an equipment problem.

 

[urumomo]

It's probably a decent compressor , it's just that tanked compressors are much better at controlling moisture in the line since it precipitates out in the tank .
A tankless operating in a high humidity environment will pump all that moisture to the airbrush .

Did you examine the needle ?
A deformed needle can cause the droplet formation .
If everything on the mechanical end is good then addressing the moisture issue would be next .

You have a moisture trap of some sorts ?
The small , inline traps can't handle the amount of moisture developed from high humidity intake air from a tankless compressor .

 

[urumomo]

If you run the AB while empty will it spit water ?

 

[VegasAWACER13]

If you run the AB while empty will it spit water ?

I did examine the needle and it is indeed bent slightly at the tip. Could that be the cause of the issue? I have ordered a replacement needle.

I have had issues with moisture. In the past, while spraying base colors and attempting detail work I have had it spit watery paint. Usually after the compressor has been running for a while. Yesterday I tried running air through the hose without the airbrush connected. And I just tried running air through the brush, at your suggestion. It didn't produce water in either case. But both yesterday and today it's been spidering the paint right after starting it up from sitting all night, and the effect seems different than it just spitting watery paint.

What kind of moisture trap would you recommend? The one I tried doesn't seem to be doing anything.

 

[urumomo]

You might be able to straighten the bent tip .
I have done that in the past , and even filed a hook-like bend off with a small file .
It depends .
and yes , that bend will wreck the airflow and prevent proper atomization .

How long did you run the brush empty ?
It will take time .

On a side note , keep an eye on the needle gland .
That's the bushing at the other end of the needle that keeps the air from blowing out the back .
If you get paint bleeding back you need to slightly tighten that bushing . Usually after you have some miles on the AB .
But only slightly tighten it a step at a time -- you should feel the slight drag on the needle when correct .
Just turn the nut less than a quarter turn at a time and check the fit , it can easily be overtightened and that will destroy that Teflon bushing .
This Thing : https://www.gaahleri.com/products/airbrush-check-valve-39-98d


What kind of moisture trap would you recommend? The one I tried doesn't seem to be doing anything.

I'm not convinced yet that it's a moisture problem .
Needs to be verified .
You need to verify there are no mechanical issues -- like the right tip and needle combo with no signs of damage ,then we need to see how much water the thing will spray out after running for a while , with no paint in the cup .

What filter did you use ?
and where on the planet are you so I know what vendors to reference .

 

[urumomo]

What is the average temp and relative humidity in the space you're airbrushing in ?

 

[VegasAWACER13]

You might be able to straighten the bent tip .
I have done that in the past , and even filed a hook-like bend off with a small file .
It depends .
and yes , that bend will wreck the airflow and prevent proper atomization .

How long did you run the brush empty ?
It will take time .

On a side note , keep an eye on the needle gland .
That's the bushing at the other end of the needle that keeps the air from blowing out the back .
If you get paint bleeding back you need to slightly tighten that bushing . Usually after you have some miles on the AB .
But only slightly tighten it a step at a time -- you should feel the slight drag on the needle when correct .
Just turn the nut less than a quarter turn at a time and check the fit , it can easily be overtightened and that will destroy that Teflon bushing .
This Thing : https://www.gaahleri.com/products/airbrush-check-valve-39-98d


What kind of moisture trap would you recommend? The one I tried doesn't seem to be doing anything.

I'm not convinced yet that it's a moisture problem .
Needs to be verified .
You need to verify there are no mechanical issues -- like the right tip and needle combo with no signs of damage ,then we need to see how much water the thing will spray out after running for a while , with no paint in the cup .

What filter did you use ?
and where on the planet are you so I know what vendors to reference .

I will run it again with no paint and see what happens. I didn't run it for long last time, so I'll give it a bit. I'll also see if I can correct the tip of the needle.

What other mechanical issues should I be looking for?

This is the water filter I tried: Master Airbrush In-Line Mini Filter

Not at all opposed to trying something much higher grade. I'm in the Washington DC area of northern Virginia.

I'll have to run down my temperature/humidity sensor. This past week, outside temperatures have been around 90F with 60-78% humidity. The place I'm in is not well sealed so it gets fairly humid inside as well.

Thanks for all the assistance!

 

[urumomo]

That filter attached directly to the brush looks horribly uncomfortable .
Is that how you have it attached ? or is it attached at the compressor end ?

When you used it did you see any water accumulate in the housing ?

 

[urumomo]

I'm suggesting filter assemblies like this below ; they also make them with desiccant bowls in series with the conventional inertial separators :
https://www.amazon.com/NANPU-DFR-02...&sprefix=air+filter+regu,aps,184&sr=8-13&th=1

 

[VegasAWACER13]

That filter attached directly to the brush looks horribly uncomfortable .
Is that how you have it attached ? or is it attached at the compressor end ?

When you used it did you see any water accumulate in the housing ?

Yes, the filter I got attaches to the airbrush not the compressor. I thought it would be uncomfortable as well but I actually barely noticed it. But it doesn't seem to be doing much. One time I noticed a little bit of moisture in it but not much.

Would the filter you suggested work with the compressor I'm using? Looks like a heavy duty set up. Happy to try it if it will attach to my compressor though.

The space I'm using to airbrush is showing 70F and 68% humidity.

 

[urumomo]

Yes , that filter assembly can be run inline near the airbrush , you'll need some additional hose and fittings .

Did you straighten the tip of the needle ?
if not , when do you expect the replacement ?
This could be a compound problem with condensate in the air supply exacerbated by the damaged needle -- or moisture only -- or we are going to need to get into exactly what you're spraying mix-wise and air pressure .

 

[urumomo]

See how it sprays isopropyl alcohol only ,, 50 , 70 % .

 

[urumomo]

When you start out with a cold compressor is this splattering an immediate issue or does it take a minute or 2 or 3 to develop ?

 

[VegasAWACER13]

Yes , that filter assembly can be run inline near the airbrush , you'll need some additional hose and fittings .

Did you straighten the tip of the needle ?
if not , when do you expect the replacement ?
This could be a compound problem with condensate in the air supply exacerbated by the damaged needle -- or moisture only -- or we are going to need to get into exactly what you're spraying mix-wise and air pressure .

So previously, I was able to do detail work for a while using a cold compressor and it would work fine at first (my inexperience at detail work with an airbrush and paint/thinner mixtures not withstanding). Then after 10-15 minutes I'd start to get spattering and I assumed this was the result of condensation. Then two days ago I started getting the spattering right off the bat and got really confused about the whole thing.

I just used the airbrush and tried running air through it with no paint. It's pretty humid here today and it did indeed start spitting water every couple of minutes. This was without the little filter I got attached. So condensation is indeed building up in the line.

I also took my jeweler's file and attempted to fix the needle tip. I'm sure it's not a perfect job but I was able to take the bend off the tip. After running air through the brush, I painted a number of small dots and didn't get any spidering. Seems like the bent tip was causing an issue.

Sounds like you're right on a compound problem?

As far as what I'm spraying, I use a mix of Tamiya, Vallejo, and Ammo Mig acrylics. I thin it with Tamiya X-20A. Given the issues I've had with moisture and the high humidity here, I've been using maybe 30-40% thinner at most, and often way less than that.