Airbrush Problems - Iwatas Not Spraying

Tools, Techniques, and Reference Materials Painting and airbrushing
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I have no idea what is going on with me lately. I own and regularly use 3 Iwata airbrushes - HP-CS, HP-CR, and HP-BH. The -CS was my go-to tool, but it quit spraying about a year ago. When the other two did likewise at virtually the same time, I sent the -CS and -BH in for service by Iwata.

When I got them back, they initially worked okay, although I felt like there was still an issue with each. They weren’t as smooth as they had been. And today, both quit spraying again. Now let me define what I mean by ‘quit spraying’ - they spray air just fine, just not paint or even solvent that I tried spraying as well.

Having just sent these in for service, which is not free - I believe I spent just short of $200 to get these two serviced, and I have yet to send in the -CR - I don’t believe I should have any issues with them now. I’ll get on a phone call with Iwata tomorrow and determine what options I have. I sent the -BH back at the end of February, the -CS a couple of weeks later, so we’re not talking about a lot of heavy usage to get back to this issue.

I am not beholden to any particular paint brand or type. I use acrylics, enamels, and lacquers on any given project. AK Interactive, Tamiya, Model Master, Mission Models, Vallejo, Gunze, Humbrol. I use thinners intended for each type of paint.

I pour in a little Tamiya airbrush cleaner between colors and at the end of every paint session to clean the paint cup thoroughly with a stiff brush, then spray that stuff to clear out anything on the needle or paint tip. When I’m done with a paint session, after the Tamiya airbrush cleaner, I disassemble the brush down to the gasket inside the brush and use a micro-brush soaked in lacquer thinner to scrub the inside. The paint nozzles are a bit more difficult - sometimes I will soak those in a bowl of lacquer thinner, other times I’ll use a fine paint brush soaked in lacquer thinner to ensure I can get the tip of the paint brush through the tiny opening in the nozzle, then use a dental brush soaked in lacquer thinner to clean the inside of the nozzle. I don’t always disassemble the air piston, but when I do, I clean that much like I do the main airbrush body and components. I always wipe the needle down with lacquer thinner.

When I’m done with that and know I will not be painting again for any given time, I will put a few drops of Badger needle juice on the needle to lube the insides.

So with this description of what I’m doing, does anyone see anything that I’m doing badly?

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Question: You say you use Tamiya airbrush thinner between colors. Does this include enamels and lacquers? Not all paints are created equal. I’ve found that IPA and Lacquer Thinner react with some paints causing them to turn into ‘cottage cheese’.

It sounds like your nozzle(s) are clogged/restricted with dried paint.

Kurt at Iwata does an amazing job cleaning/refurbishing airbrushes and knows what he’s doing.

I’ve owned several Iwatas for 20+ years and my HP-CS is my workhorse. Any issues I’ve encountered can usually be attributed to something I’ve done and can be normally fixed (relatively) easily.

Rob
Iwata Padawan

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Oh, I am virtually certain it’s something I’m doing. With regard to Tamiya, I have been using their lacquers more frequently these days, but I do still use acrylics when that’s what I have of a particular color.

I soaked both brushes nozzles and needles last night in lacquer thinner. This morning the HP-CS sprayed medium but there was bubbling in the paint cup. I believe that does point to dried paint somewhere in the body. The HP-BH did not spray medium after all that soaking last night.

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So are you saying that these airbrushes didn’t work right after you got them serviced? Like they didn’t work at all, even after service?

Are you thining your paints for airbrush use? Nearly all paints need to be thinned. The only exception are paints that specifically say they are pre-thinned for airbrush use.

And if you are thinning your paints, are you using the right stuff. Some paints do not agree with certain thinners. And certain combos can cause paints to clump up which would clog the airbrush.

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Check your front o-ring. It may not be in place properly or have a split or nick and is letting air in.

iwata-eclipse-cs-airbrush-replacement-parts-diagram-1400x6001
iwata-eclipse-cs-airbrush-replacement-parts-diagram-1400x60011400×600 64 KB

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Both worked for a time. I sent the -BH in back in February, the -CS in early March. I wasn’t real happy with either once I got them back from Iwata. The performance wasn’t as smooth. Bubbles in the cup. That kind of thing.

As for thinning, yes, I do thin and I do so with branded thinners for the paint I am using. Now, it just occurred to me that I have not been thinning the Tamiya lacquers, so that could very well be my problem. I have been using Tamiya lacquers frequently on projects since those became available here in the States. Yes, I should be thinning those with lacquer thinner (not sure Tamiya has a thinner for that line of paints, but will check).

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Thanks, I’ll check the o-ring. I thought that was replaced with the recent service work I had done on it, but maybe not.

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I have had cup bubbles from that before.
From above though your issue is likely not thing the lacquers. Tamiya does have a lacquer thinner. I use it for thinning all my Tamiya paints regardless of type.

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Interesting that you would have problems right after getting them serviced.

To thin Tamiya lacquers, I use Mr Leveling Thinner. It works great and slows down the drying time on the paint just a bit. But if you would like to stick to lacquer thinner, any thinner should work, including the cheap stuff at the hardware store.

In that exploded view @Tcoat shared, see the two o-rings? If your front one is bad the rear one is the same size and can be used as a spare.

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After soaking last night, after soaking today, and finally after spraying Mr Leveling Thinner, I was able to get both airbrushes to function as expected. I thought the -CS still had a bit of bubbling going on, so it’s back to a soak, but the -BH sprayed perfectly well.

I did inspect the O-ring but could not discern any visible damage to it, so should be okay there.

I still have a third brush that I need to send back for repairs, but I think I’ll start by breaking it down and soaking it as well. And as a result of being stuck in the water, I’m eyeing adding a couple of new Iwatas to my inventory. Still have to consider that, money doesn’t grow on trees, but it’d be nice to have a back-up if nothing else.

Thanks to everyone for their helpful suggestions!

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I thin Tamiya LP lacquers 50/50 with Mr Leveling Thinner, the results are phenomenal. Si in other words one part paint to an equal amount of thinner. But Tamiya LT will work too of course, you just get better leveling out with the Mr. I’d venture to say that even hardware store LT would work compared with not thinning at all. To shoot straight LP lacquer you’de need about 40lb of air and a .7 or larger tip in your airbrush. IE not gonna work.

I’ve seen where some guys thin either Tamiya acrylic or the LP lacquers more than 50/50. So more thinner than paint, especially with flat colors. There generally isn’t an issue with product coming out of an airbrush from too much thinning, as airbrushes spray straight thinner great. It’s the thick stuff they can’t grunt out.

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