Thread: Paint won't spray at low pressure

Hi all! I've just discovered this forum, and it looks like it will be very helpful. I use an Iwata Eclipse CS for spraying acrylic hobby paints (Polly Scale, Tamiya, Model Master, etc). My compressors are a 25-year-old Badger 180, and a new Campbell Hausfeld compressor with a 3-gallon air tank. (The silence is wonderful!)

For large areas I spray at about 20psi, down to about 12psi for detail work. However, now I when I spray below about 22psi, I get air, but no paint. This even happens when using plain distilled water to troubleshoot. At 22+ psi, I get a normal stream of liquid. At 20-22psi, I get intermittent liquid flow. It gives an burst of full flow, then tapers off to nothing within less than a second. Below 20psi, no liquid comes out. There's no bubbling back into the cup, and the airflow seems normal. The symptoms are identical with either compressor.

I've stripped the airbrush down to individual parts and cleaned it (several times) without helping the problem.

Any ideas or thoughts would be greatly appreciated!

Thanks,

Peter

Just a long shot here but are you using the same regulator and gauge setup (for both compressors)? The small gauges that come with most regulators are cheap pieces of crap and can really go bad on you. What you think is 20 psi may actually be less due to the inaccuracy of the gauge. We throw them out regularly at work due to them being way off.

Another thought, is at the lower pressure, any air leaks will take away what you think the pressure is at the airbrush...

Those are my best two shots at your problem, I'm sure others will give better advice soon.

Oh yeah, welcome to the Forum.

Cliff

That was going to be my next suggestion, blockage..... hope you can figure it out....

Cliff

With any airbrush or spraygun, there needs to be a balance between the airpressure the nozzle/needle size on your brush, and the paint viscosity.
Paint needs to be thin enough/low enough viscosity to be able to be pulled into the path of the air that is coming through the nozzle cap. If the brush you are using is a siphon feed brush, then it will require even more air pressure to pull the paint up from below.

If the paint is too thick, then it won't spray, especially at the lower pressures. If you can't get straight water to go through your brush, then your problem is more likely an issue of something clogging the path of the paint flow.

When you say you "get a burst of flow", do you mean a burst of flow of the liquid/paint? Does the air flow still stay consistent through the airbrush when you do this?

If the airflow stays consistent, then you have something in the paint path. It could be something in the cup/bottle, the nozzle, or the trough that runs below the paint cup/reservoir on your Eclipse CS.

Do you reduce, mix, and strain your paint before it goes into your brush?

How thin/thick do you reduce your paint to?

If there are clumps in your paint, then they may be big enough or thick enough to block the normal flow of paint through your brush when you use the lower pressures.

Originally Posted by redneck

will you consider pumping a innertube up to a different numbers of PSI and check the pressure with a known to be good tire gauge
use both compressors to compare the psi reading

Good idea, but I have neither a known good tire gauge, nor an innertube. My thought is that since both gauges agree, it's extremely unlikely that both are wrong by the same amount.

Peter

Fontgeek,

Thanks for all the ideas. I've been spraying the same paints, with the same techniques and thinning ratios, for years, and the problem has cropped up within the last couple of months. For me that's only 2-3 spraying sessions, since I spray relatively infrequently.

The air hose is the only common element, and I've blown the hose out from airbrush end to compressor end to dislodge anything that might be caught in it.

>When you say you "get a burst of flow", do you mean a burst of flow of the liquid/paint? Does the air flow still stay consistent through the airbrush when you do this?

Yes, I get a burst of liquid flow. The airflow stays constant throughout the spray using the new compressor. On the old Badger compressor, the pressure bleeds off during the spray, which is why I purchased the new compressor. I figure the Badger is near the end of its life, having bought it in the early 1980s. (And I'm less tolerant of its noise now too!)

>If the airflow stays consistent, then you have something in the paint path. It could be something in the cup/bottle, the nozzle, or the trough that runs below the paint cup/reservoir on your Eclipse CS.

I've stripped the airbrush to components, and cleaned everything in lacquer thinner. It looks and feels as clean as it always is.

> Do you reduce, mix, and strain your paint before it goes into your brush?

Yes to thinning and mixing, no to straining. I've never had to strain the hobby paints I use. When I notice and thickening or other paint problems in the bottle, I toss it and get a new bottle.

> How thin/thick do you reduce your paint to?

It depends on the brand and color, but generally 30-50% thinner. I use distilled water for a thinner, since I have found through experience that it works as well as the manufacturers' thinners.

> If there are clumps in your paint, then they may be big enough or thick enough to block the normal flow of paint through your brush when you use the lower pressures.

If I notice any clumps or debris in the paint, or when it separates and gets difficult to mix properly, I replace the bottle. It takes me forever to use a whole bottle, so the commonly used colors generally get replaced at least annually.

Peter

Try straining your paint through a tea strainer and or a section of pantyhose.
Paints can settle, separate, and even curdle in temperature extremes (hot summers, cold winters, etc.) and all it takes is a little bit of thicker stuff to slow up your brushes performance. While the packages may look the same from purchase to purchase, the paints them selves will vary from batch to batch, and from color to color, Createx and AutoAir have suffered from this issue for many years. As far as the reducing goes, don't worry so much about set ratios, worry or work at getting the paint to the proper viscosity. That's typically about the thickness/viscosity of milk for most paints.

If the air is coming through the brush all right, then the problem is not your hose, the airvalve, or the air passage within your brush. All that leaves is the path the paint takes and the paint itself. If it's not the paint, then it's the path it takes through your brush from the reservoir/cup through the trough at the bottom of the cup, along the needle, and through the nozzle and the needle cap.

There just isn't that much to the airbrush, you have already stated that it isn't the air, and that you have thoroughly cleaned your brush, so all that's left is the paint.

While laquer thinner is great for urethanes, enamels, and laquers, it isn't necessarily the best cleaner for all paints or paint types. and all it takes is a little flake or blob of stuff to muck up the works.

Fontgeek,

Good suggestions about the paint. The acrylic model paints have the same lack of consistency, so I eyeball the paint/water ratio till it looks right. I do have clogging problems if I don't thin it enough, especially because the acrylics dry so fast.

What would you suggest for cleaning acrylics? The hobby community swears by lacquer thinner, but I'm always open to suggestions. I'm sure you do more airbrushing in a week than I do in a year!

Since the problem persists even with plain water, I'm thinking I've missed something in cleaning. Or is it possible the nozzle or needle is damaged?

Peter

Originally Posted by Sabreghost

petero, sounds like exactly the same trouble i'm having with my cs.. i'm going to send it back to the dealer and see if he can work out what the problem is, willl let u know what i find out

Thanks Sabreghost. Hopefully the dealer can shed some light on the problem.

Peter

Use a jewelers loupe or a strong magnifying glass, and do a careful inspection of the nozzle both inside and out, and of the taper and tip of the needle. If everything is clean and in good shape, then use the loupe to inspect the paint passage that sits behind the nozzle (when it is properly installed in your brush).

If your paint has been reduced and strained, then you probably missed something in the cleaning. The steps you take in cleaning, and the order you do them in can make a huge difference to how your brush performs. The spraying out of solvent should be the LAST step in your cleaning while the brush is still assembled.

As far as cleaning goes, I tend to use plain water whenever possible. It's easier when the paint is fresh, and it's also easier on me, the brush and the envrionment, however, I know that there are times when we can't clean our brushes right away, or we are working in conditions that make the paint dry faster or clog up the works. My first choice is to use what the manufacturer reccomends for their paint, as often as not, that is usually a simple detergent rebottled with their brand name on the label. For general cleaners, I use Brush FLush or EZ Airbrush cleaner for my water based paints and colors. But you need to be careful with what you use. Some solvents can have adverse reactions to certain types of paints or colors. For instance; using rubbing alcohol on some water based paints makes the paint go gummy and turn into little balls within the airbrush. What a nightmare!

Originally Posted by Sabreghost

just a quick observation today, i was using my hp-c+ and it started doing exactly the same thing. i found that the nozzle cap was loose. that makes me think that m,aybe the hpcs is sucking air , most likely place would be the packing head o-ring. so i'm gonna get one of those and see if it makes i difference..if this was suggested in any of the above posts, my apologies

Thanks for the tip. I'll check the packing ring to make sure.

Peter

Thanks for the additional tips, Fontgeek. I generally use Windex to clean the airbrush. The ammonia in it works well for cleaning the modeling acrylics I use.

I'll find a loupe and do the inspection you suggested, and see what I find.

Peter

Don't use Windex or other ammonia based cleaners in your airbrush.

While some manufacturers used to reccomend it for the initial cleaning on their brushes, most have stopped even that bit of advice. It was originally reccomended by the manufacturers because it was a quick solution to ridding your new brush of the packing grease remnants that might contaminate your paint, but most if not all have stopped the recomendations at this point.

Ammonia is an oxidizer, it breaks down both the chrome and the brass of your airbrush, it also makes rubber gaskets and seals brittle.
Windex themselves used to reccomend their product for use on chrome back in the 1970's ("Your car ain't cool if the chrome don't shine!") but after a year and a half they pulled those ads and reccomendations after the major car manufacturers started getting complaints about the chrome breaking down from the use of their product.

I would also avoid the use of other household cleaners for cleaning or reducing your paint. Many people have found that something in cleaners like Fantastic break down and remove the chrome from the reservoir/cup after a short while. You also don't know what the solvents and detergents will do to the longevity and durability of the paints you are spraying. On top of all that, you are putting chemicals into the air that may be hazardous or fatal to you, your pets or plants. While some cleaners may be safe to use with a sponge, that doesn't mean they are safe to inhale.

Saberghost, if you weren't getting bubbling back in the cup/reservoir when you tried to spray, then that wasn't your problem.

The paint is not pushed out of your brush, it is pulled out through the nozzle opening and atomized as it exits the nozzle cap. If you are seeing lots of paint inside the nozzle cap, then you definitely have an issue. Try carefully snugging down the nozzle, and if that doesn't work, try the O-ring, and or the use of bees wax on the threads of the nozzle (if the nozzle is threaded).