Testors Aztek Review

1/2011

And now for something completely different.

No airbrush is more controversial than the Testors Aztek. It seems that people either love it or hate it. Some of the ones who don't like it claim that it just doesn't feel right, or they can't get good results. But most say they like it fine until it breaks, and it breaks often. One commenter wrote that he needed two because one was always sent back for repair. In the past, Testors offered a lifetime warranty, but I understand this has now been shortened to 3 years. The warranty is void if you open the body.

So, I was really curious how one airbrush could generate such diverse opinions. I noticed one on E-bay with a starting bid of $24.99 and no bidders. So I bid $25, and by golly I got it. It's a model 3000S. Or at least I believe it's a 3000S, as there is no model number on the airbrush or the case, and I didn't get any paperwork. But, it appears to be the same as the one in this helpful web page. Apparently it is no longer sold. I couldn't find it on Testors website. Most modelers seem to use the A430 or A470. But, they all appear to be pretty much the same internally, and use the same nozzles and cups. The A430 lacks the trigger adjuster that can make it act like a single action.

It came in a nice plastic case with 4 nozzles. A 6 foot plastic hose was coiled up in the bottom.

There were also 2 little plastic plugs and a tiny funnel. I didn't get a paint cup, but I knew that when I bid on it. The case makes a nice holder for the brush.

The 3000S is a double action side feed airbrush. Whatever you might think of it, you have to admit that it is innovative. It's not like any other airbrush that I know of. Most internal mix airbrushes have a needle that runs from front to back; not the Aztek. It combines needle and nozzle in one piece. Most internal mix airbrushes are metal. The Aztek is mostly plastic. But it's a tough plastic. Apparently it is not affected by most solvents, including lacquer thinner and acetone.

The first thing I did was to clean it up. There were chunks of rubbery dried paint in the paint path of the body that came out with some lacquer thinner and a little probing. And, I cleaned the nozzles according to instructions I found in this thread on the ARC forums. If you own an Aztek, I strongly recommend you read it.

First Impressions

It has a very light and dainty feel. It only weighs 30 grams. Like all my airbrushes, the trigger down pressure is more than I like. But, the trigger has good traction, and the textured plastic body is comfortable although slightly slippery.

What's inside?

I bought this airbrush with the intention of taking it apart, so I wasn't worried about the warranty. The A430 and A470 models have to be pried apart, but the 3000S is held together with two screws. They are special star shaped security types with a center post, but I found that one of my jeweler's screwdrivers would jam in and do nicely. The inside of the body was perfectly clean.

The pictures are just slightly larger than actual size on my monitor.

The arrows below show parts that are metal in this model, but plastic in the A470. The plastic parts have been known to break if the trigger is forced.

Here is an exploded view to give an idea how the Aztek works.

There is a spring in the nozzle that pushes the needle back, and a larger spring in the head of the airbrush that forces the needle all the way forward. The larger spring connects to the pin pivot, which I have shown out of position so that you can see the spring. The white line shows where the pin pivot connects to the needle control pin. The needle control pin slides through a hole in the head to push against the needle and control its position. The pin and the hole it goes through are a close fit and act as a seal to keep paint out of the inside of the body. Pulling back on the trigger retracts the needle control pin and the spring inside the nozzle pushes the needle back to increase paint flow.

The trigger is suspended between the clips as shown, which leaves it loose so that it can be pressed down against the air valve. There is a groove in the bottom of the trigger that the lever from the valve slides in. The air valve is really strange. In conventional airbrushes the air valve is a poppet type, and is pretty much open or closed. When this valve is free as shown, the spring forces a plunger down against flexible tubing inside the valve and pinches it off. Pressing down on the lever causes the entire black portion to tilt up against the spring and lift the plunger, allowing air to pass. As a result, control is very linear, and air flow can be controlled from a whisper to full blast. To me, it feels very mushy.

The trigger adjuster moves the bottom of the trigger fore an aft. When turned clockwise as seen from the rear, it causes the trigger to pull back on the needle as it is pressed, thus acting like a single action airbrush. Turning counterclockwise, you reach a point where pressing on the trigger doesn't move the needle. This gives normal double action. If you keep turning the adjuster counter clockwise, you still get double action, but there is a gap when you pull back where nothing happens.

There is a website that was very helpful in getting this thing back together. You can see it here. It is in French, but Google does a pretty good job of translating.

Here is what the nozzle consists of. The inner part clicks when it's fully inserted. Supposedly, they can be cleaned by flushing. The outer blue part doesn't really get that dirty, as the paint flows through the inner lighter piece. The needle and spring can collect paint. I've seen recommendations that they be dismantled after each use, but I also saw a comment from a guy who has used an Aztek for ten years and he just drops them in lacquer thinner. The little hole in the nozzle that the needle goes through looks very fragile. I would never probe this with anything during cleaning. A toothpick could easily distort it. I didn't get a wrench for the nozzles, but finger tight should be enough to seal plastic against plastic.

Trying it out I thought I would have to buy a cup to see how the Aztek would spray. But, I decided to give the little funnel shaped thing a try. As you can see at the right, I put a plug in the right side and the little funnel in the left. It turns out that a couple of drops can be put in it and get sucked inside the brush and go quite a ways. I don't know if this is what the little funnel is really for, but it works.

At first, I tried plain water. I soon found that the tan fine nozzle blew bubbles in the cup, and the blue heavy nozzle wouldn't shut off. But, luckily, the gray general purpose nozzle worked fine. I think they may have had some rough treatment. I also tried the pink splatter nozzle,and it worked although I don't know what I'd ever use it for. I was trying to figure out the problems with the fine and heavy nozzles, and I got to looking closely at the needles. Here they are on the right. I darkened them with a Sharpie to make them show up better. The top one is the fine, then the medium, and bottom the heavy. I was surprised to find that they all look alike. The differences must be in the plastic parts. I got the heavy nozzle working by re-installing the needle. The fine nozzle had some roughness at the base and wouldn't seal to the body.

The plastic hose is a good fit for this light airbrush. A heavier hose would be clumsy. However, you can get an adapter that will allow the use of standard 1/8" hoses such as Iwata or Master.

I sprayed some ink on paper towels with the medium and heavy nozzles. It sprayed very nice and fine lines were no problem. Since these are used nozzles with an unknown history, that's not bad.

Having the hose attached to the back of the brush was handy and the body was comfortable to hold. But, I really don't like the spongy feel and pressure of the trigger. On my other brushes I have modified trigger pressure. But, I can't on this one.

I think the trigger adjuster is a bit of a gimmick. But, once you get it set right and leave it alone, it's OK.

I cleaned up by flushing with water and a little Windex. When I removed the nozzle and took it apart, it was clean. Then I pulled the little plug and funnel off and there was a little ink on them. So I cleaned them and flushed out the holes. I think this is probably a good idea after each use.

Conclusion

As far as quality of spray, I'd say it does a perfectly fine job. This can be clearly seen in the videos that Brett Green has done. I don't like the feel of the trigger, but that's a personal thing. I notice that Brett uses his thumb on his. I added a couple of leather pads to the body that make it easier to grip.

A lot of the failures seem to be due to paint getting inside the body. In fact, some recommend taking it apart regularly to clean it, even though this voids the warranty. If paint gets inside, it must be leaking past the needle control pin. Why this happens to some people and not others, I can only guess. But here's a possibility. There should normally be very little pressure in the paint chamber. In fact, capillary action in the close tolerance around the pin should keep paint from seeping through. But, the paint cup connects to the brush through a narrow tube. If the user were to hold something over the nozzle and back flush, the pressure inside the head might be enough to blow paint inside the body. I would never back flush with this airbrush.

If paint does get inside the needle control pin seal, I wouldn't force the trigger. The linkage may break. It's not a good idea to force the trigger on any airbrush, but especially this one because of the plastic parts. Instead, I'd let a little lacquer thinner soak in the front of the body to free things up. This seal seems to me to be the weak point in this airbrush. You can't just pull the pin and wipe it off like you can the needle of a conventional brush.

Another problem I've read about is air blowing from the body. Here's what might cause that. Notice in the exploded view above, the little air tube that goes to the head. This tubing is very soft and is just a push fit into the head and the air valve. It wouldn't take very much pressure to cause it to pop out. If something blocked the air path, like paint build up in the head or even a finger over the nozzle, this might happen. Needless to say, you should avoid this.

Much is said about how easy this brush is to clean. Yes, it's pretty easy. Just flush with thinner, remove the nozzle and soak in more thinner, maybe take the nozzle apart and brush the needle, pull the plug on one side and the cup on the other and flush out the head. But, I don't see where that is any less work than what you really need to do to a conventional airbrush. I think many people make a bigger job of it than it has to be.

It is very easy to change nozzles. It takes a little longer to change parts on a conventional airbrush. But, I hardly ever need to do this. The 155 gives a pretty wide range of coverage without changing anything. I suspect the Aztek medium nozzle will also serve most purposes.

The deal killer for me is the fact that you can't buy internal parts. I can understand why Testors doesn't want you in there. It's a bit tricky to get back together. But, after the 3 year warranty is up, it becomes a disposable airbrush. I'd feel much better if I could purchase a replacement for the head when that needle seal wears out or gets damaged. Badger tells you not to change their needle bearing, and to let them do it for free. But, you can buy the needle bearing and try it yourself if you really want to. I like having that choice.

In spite of my reservations, there is something about this airbrush that still attracts me. It is very light and comfortable in the hand, and works just fine. And, it seems that with proper care, and maybe some luck, it can last a long time. If you don't mind the feel of the trigger, it's really a nice brush.

If there are any happy Aztek users who want to add some helpful hints, I'd love to hear from you.

Postscript

Note: I do not recommend you try this as it will certainly void the warranty, and the part is not replaceable.

I still wasn't happy with the pressure needed on the trigger to control air, so I decided to have another look at the air valve.

The photo below shows what I did.

As you can see, I unwound some of the spring with a jeweler's screwdriver. I hooked the valve to my compressor and set the pressure to 25psi. Then I continued unwinding until the spring was just barely able to block air flow. This is the point shown above. Then I clipped the spring just above the post and tucked the remainder back in place. The trigger is still not as easy to press as my other brushes, but it is better. This might affect the long term reliability of the valve, but I'm willing to take that risk.

Feedback

I got some good comments from George Collazo. He is a long time Aztek user. He bought an A470 back in 2000 and had no problems with it until 2009. At that time he sent it to Testors for warranty repair and quickly got one back that looked like brand new. It has worked fine ever since. Last summer, he purchased the version with the metal shell and likes it better because of the heftier feel, and he says the balance is better. But, he misses the rubber grips on the sides of the 470.

George says he has never had any problem with paint getting inside. He thinks this may be because he is always careful to keep the airbrush in a nose down attitude when he sets it down and there is paint in it. He also said that the spatter nozzle works well to simulate mud on his models. George also owns a Paasche Talon, which he says is a fine airbrush. But, he still mostly uses the Aztek. He says it is more comfortable to hold.

Thank you George for the feedback.

I got an e-mail from Harold Mohr. Here is what he wrote:

Hi Don, thought I would pass along some info on the A470, I had an older one that worked great for painting my wood carvings. Feb. of this year it quit working. When you pulled back on the trigger nothing would happen, being as it was twelve years old I pulled it apart and found the groove where the trigger mechanism fit was worn to the point it would not hold the prongs any more. I contacted Aztek and was told to send it to them for replacement. I was totally honest about taking it apart but the rep told be they were having problems with the trigger mechanism on the older models. Within a week of sending the old one in I got the new one, and it has a lifetime warranty.

So, even if you have opened up your Aztek, you may be able to get a replacement. Thanks, Harold.

I heard from Mario Liegghio. He said he bought an A470 when they first came out and used it for many years. And, he liked being able to control air flow with the trigger. Also, he said the plastic nozzles are almost immune to paint build up. He did take it apart periodically to (in his words) overhaul it. Eventually, the flexible tubing inside the air valve fatigued and stayed closed, and he replaced it with a piece of heat shrink tubing. Last year he got a great deal on a used Badger 150, and the Aztek is now pretty much retired.

Thanks, Mario.

More Postscript

I just watched a video about adjusting the Aztek for use. The guy is confused about how the roller works. It doesn't force the needle forward, it just restrains it. But, it got me thinking. The plastic nozzle is really fragile. Setting the roller the way he does could protect it and make it last longer. So, if you own an Aztek, you might want to watch the video.

Here is a link to a forum post about Azteks by Robert Kennedy. He makes some interesting points.

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