airbrush/compressor help

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ziggysdesk
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airbrush/compressor help

Post by ziggysdesk »

Hi guys,

I've been having this problem the past month, mostly when I try to do wet coats. For the first few minutes of airbrushing, everything will be fine, but then afterwards I'll get a splatter, bigger drops of paint? water? will hit the model. It usually dissolves or evaporates a bit and can be covered up somewhat with successive wet coats and sanding afterwards.
I noticed recently it happens more often when my compressor is re-filling the tank.

I checked my moisture trap and it was full, so I thought that might be the problem. I emptied the trap, cleaned/dried it and also drained the tank. There was some rusty water that came out, so I left valve on the bottom open for 2 days to dry out, also ran the compressor to blow more moisture out if there was any. After this I thoroughly cleaned my airbrush and then went to spray some more clear coat today and I had the same problem.

I have one of those cheap master airbrush compressors from amazon, it has a moisture trap, and I also have a GSI creos dust/drain catch at the end of the hose.

I've been using the same paints/thinner and ratios for over a year with no problems so I'm not sure if it's that.

Any help is appreciated, I can't quite figure it out!

Thanks
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CaptainMark
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Re: airbrush/compressor help

Post by CaptainMark »

The full moisture trap was likely contributing to some small degree, but obviously isn't the main culprit.

Have the seasons, weather, or humidity changed any reasonable amount in your area over the last month?

And have you tried draining and airing out the compressor tank again, it would be interesting to know if it's got the same problem inside, and might confirm the issue if it's got moisture in it.

Also, have you tried airbrushing with a different brand of paint than you normally do?

And, is there anything else that might have changed in your airbrushing setup or environment, even if it seems insignificant, in the last month?
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Re: airbrush/compressor help

Post by CaptainMark »

Actually you could be getting tip dry for some reason and the Compressor filling the tank might be somehow putting pulses of pressure through your airbrush which is dislodging the dried paint in the needle tip in little blobs, causing the problem.

What kind of paint are you using? Tip dry is most common I acrylics but can happen in any type of paint really given the right conditions.
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Re: airbrush/compressor help

Post by Moskie »

A lightly bent needle tip could be the problem here. If the needle is bent of has a burr on the end a little drop of paint will form on the tip. If the airflow increases this is blown off as a droplet, the way CaptainMark described before.

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Re: airbrush/compressor help

Post by willster127 »

I run into this every now and then and find it's mostly self inflicted. My theory is that if I don't release the paint flow prior to shutting off the air paint can flow through the needle in to the nozzle. If I then reintroduce the air that paint shoots out as a blob and onto the model, I have to very cautiously stop the paint flow after the pass is complete, then shut off the air, then reintroduce the air, start the paint flow and start the pass over the model.

Once I figured that out and started focusing more on the technique my issues went away.

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Re: airbrush/compressor help

Post by ziggysdesk »

CaptainMark wrote:The full moisture trap was likely contributing to some small degree, but obviously isn't the main culprit.

Have the seasons, weather, or humidity changed any reasonable amount in your area over the last month?

And have you tried draining and airing out the compressor tank again, it would be interesting to know if it's got the same problem inside, and might confirm the issue if it's got moisture in it.

Also, have you tried airbrushing with a different brand of paint than you normally do?

And, is there anything else that might have changed in your airbrushing setup or environment, even if it seems insignificant, in the last month?
CaptainMark wrote:Actually you could be getting tip dry for some reason and the Compressor filling the tank might be somehow putting pulses of pressure through your airbrush which is dislodging the dried paint in the needle tip in little blobs, causing the problem.

What kind of paint are you using? Tip dry is most common I acrylics but can happen in any type of paint really given the right conditions.
Weather has been pretty consistent lately, 70-80 low humidity. I did try to drain the tank again last night but nothing came out this time. I started using Gaia paint when this first began to happen, but I noticed the same problem a few days ago with Mr. Hobby Clear Coat as well so I ruled out the difference in paint as a factor. Mainly use lacquers, and I'll spray some thinner between refills of paint, would that be enough to get rid of the dried paint on the needle tip or would I have to wipe it down?
Moskie wrote:A lightly bent needle tip could be the problem here. If the needle is bent of has a burr on the end a little drop of paint will form on the tip. If the airflow increases this is blown off as a droplet, the way CaptainMark described before.
I had considered this.. my airbrush does have a really fragile needle/nozzle. Right after I got it I damaged the nozzle somehow during cleaning, and it was spraying out a little paint with just a trigger press for air only. Have since replaced the nozzle, so I always try to be super careful while cleaning now. I think I will switch to my old airbrush and try the same paint combo and see if it's specific to the new airbrush.
willster127 wrote:I run into this every now and then and find it's mostly self inflicted. My theory is that if I don't release the paint flow prior to shutting off the air paint can flow through the needle in to the nozzle. If I then reintroduce the air that paint shoots out as a blob and onto the model, I have to very cautiously stop the paint flow after the pass is complete, then shut off the air, then reintroduce the air, start the paint flow and start the pass over the model.
Once I figured that out and started focusing more on the technique my issues went away.
This is interesting, I have never really considered how I stop the paint flow and if it's before or after the air. I'll have to keep an eye on that next time too!

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Re: airbrush/compressor help

Post by ziggysdesk »

Hey guys thanks for narrowing it down for me. I forgot I had a spare needle so I switched needles and used the same clear/thinner combo with 0 problems. I filled the cup twice and emptied it in one trigger press and there was no splatter at all.

I took a pic of the 2 needles. top one is the one that was giving me problems, bottom one is the spare. I can't really spot anything different about the 2, but maybe someone with a better eye can tell me if there's a noticable difference?

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Re: airbrush/compressor help

Post by phicks »

Could it be the mixing of your paint? I don't think stirring is enough , I use one of those battery powered mixers
and it works great.
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Re: airbrush/compressor help

Post by CaptainMark »

Fantastic that you found the solution to your problem! Even microscopic abrasions on a needle tip can impact the quality of the spray pattern as you've found out. There are ways you can polish your needle tip or perhaps use needle lubricant to even out the micro-abrasions. But given needles aren't super expensive I'd be more inclined to just bin the old one and put another spare in your stash.

As to your question about tip dry cleaning...
ziggysdesk wrote: Mainly use lacquers, and I'll spray some thinner between refills of paint, would that be enough to get rid of the dried paint on the needle tip or would I have to wipe it down?
In my experience spraying thinners between colour changes is not sufficient to clean the airbrush as it leaves quite a reasonable amount of paint on the needle where it's housed inside the airbrush body (see pic below) and it's highly unlikely to remove accrued paint on the needle tip. I would always recommend removing the needle and wiping it down fully between colour changes, from the picture below you can see that a flush/rinse won't always get all the paint and you'll also be able to more easily clean the tip.

I've written a bunch of tip dry and needle cleaning articles recently which, if you're interested in reading, you can see here. (nothing for sale, it's just a blog of mine I write on for the enjoyment of it.)

I thought I had a picture of moderately bad tip dry so you can see how a flush or rinse probably wouldn't do the trick, but the picture alludes me right now, if and when I find it I'll post it just for curiosity sake.

The image below shows Tamiya acrylic paint remaining on the airbrush needle after a full clean of the airbrush cup and flush of the airbrush with general purpose thinners until (apparently) clear thinners was sprayed.
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ziggysdesk
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Re: airbrush/compressor help

Post by ziggysdesk »

CaptainMark, thanks for the help! I'll also try polishing the needle and see if that makes a difference. Love the blog, some good stuff in there! thanks for sharing.
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