Thread: Iwata Revolution Clogged with Urethane Clearcoat

Hello,

i'm new to this forum. great resource you have here. I've looked around the trouble shooting threads and couldn't find the answer i'm looking for.

I have an Iwata Revolution CR. Great airbrush. I probably made the mistake of trying to use it for HOK Urethane Clearcoating. It was working pretty good for a while. but after cleaning it and leaving it assembled, the next time, everything would still be stuck together and I would have to clean it all over again. Which was fine. I should have kept up with that routine. So this last time, i figured, if I cleaned it and left the parts un-assembled, maybe I would have less problems when I re-assembled it.

Well, when I did, it would not spray at all. No air was getting past the trigger. I took apart the valve and cleaned everything, but it's like the trigger itself won't let air go through. I purchased new air valve parts thinking the new O-rings might help. but haven't switched them yet.

when replacing the valve and the valve guide, i noticed a hole just below the o-ring in the valve guide. is that supposed to line up in a certain way? I tried parallel to the nozzle and perpendicular, but both with no luck...

any help would be appreciated. It would be a bummer to not be able to use this AB any longer.

in the meantime, i've purchased an inexpensive spray gun designed for urethan clear coating.....

thanks

What process do you use to clean your brush?
Be explicit in the steps and the materials you use to do it.
The more we know, the easier it is to come up with a solution, not just to your current problem, but maybe some longer term issues too.

normally, i just pull the needle out, clean it. I take off the needle and nozzel caps and clean those. I clean the cup. I try to make sure nothing is clogging the nozzel itself. I don't normally take apart the valve and clean that part.

Thanks Yardartnut,
that's what I was doing before and should have just stuck with it. But the problem now is that I can't seem to get air passed the trigger. when I press the trigger, no air is coming up. when I take the trigger out and used the end of the needle (blunt side) to depress the valve, air does come out. So something around the trigger (or the trigger itself) is preventing air from getting into the AB....

What process do you use to clean your brush?
Be explicit in the steps and the materials you use to do it.
The more we know, the easier it is to come up with a solution, not just to your current problem, but maybe some longer term issues too.

If you can get air through the airvalve, then cleaning the needle is not the issue, answer the questions, and we can help.
Shooting off ideas in the dark can just lead to more frustration, and possibly do some damage to you and or your airbrush.

What Yardnut said ^^^^

If you are getting air up through the trigger piston hole when you use the butt end of the needle to depress the airvalve, then your trouble may be a good bit deeper in your airbrush than just the trigger piston and it's seal, but without knowing how you clean your airbrush, we're just shooting in the dark.

aha! this makes a lot of sense. when i screw back this plate, I was worried that it was screwing all the way. I dont' have a great tool to screw this microscopic plate back in, but will try a bit harder.

Originally Posted by yardartnut

Sounds like the airvalve pin is not completly seated as far as it needs to be.....
Try this...
at the bottom of the airvalve [where the hose hooks in] is a small plate that hold that assembley in place ..it has 2 slots on each side.
Be sure that is screwed all the way up...that will cause the pin to go high enough for the trigger to push it down...it just sounds like your trigger is not reaching that pin to me I may be wrong on this but if all this fails >>>>>>>>>>>>>>>>>>>




Call Iwata tech.they are very customer friendly folks....
503-253-7308 ext.10
8am-12
1pm-4pm

I hate to sound like a pessimist, but, if you have or had junk/contamination in the air valve, then you also have to look at how the contamination got there, and where else it may have gotten to.
If you submerge your airbrush in solvent during cleaning (or any other time for that matter), you risk having junk float into areas like the air valve, the air passage within the airbrush body, the trigger well, etc.
While I'm glad you seem to be getting a handle on the contamination in the air valve, and the reassembly of it, I think you also need to be concerned with how it got there, and where else it may have gotten to.
The seals and packing around the trigger piston and the air valve assembly were never meant to be exposed to paints or solvents, and the use of solvents on them can destroy them in a hurry, and that just adds another layer of gunk to your problem, not to mention the added cost for replacement pieces, and the pain of installing them.
This is why I keep asking what your cleaning routine is. Don't just look at one small symptom, look for the cause too! Yes you still need to cure the symptoms, but if you can avoid the cause of them in the future, you will save yourself money, time, and frustration.

You can get clip ring pliers at most good sized auto parts stores for around $8, there is a tool for working the small screw in rings, but unless you plan on doing this a lot, a tiny cheapo screwdriver ground down will probably be your best bet.

Thanks guys. you are a great resource. I'm glad I came here.

so I called Kirk at Iwata and he was very helpful today. Here's what I did:

1. took apart the air valve again. Tweezers work great. thank you!
2. took out the valve and valve sleeve.
3. took a Q-tip with lacquer thinner and thoroughly cleaned the inside of the stem
4. replaced the valve, the valve sleeve, and the o-ring that goes on top with new parts.
5. Thought it was gonna work for sure, but no air coming through!! I could hear a bit of air, but that's it!

I am going to take out the valve again and try swabbing inside of the stem with more lacquer thinner. I still think the hole inside the stem is clogged with urethane....

Yardart, I appreciate your sentiment, but it kind of danced around the point I was trying to make, and that was how or why his brush stopped working in the first place. Toybot stated that the brush was not cleaned, and when the attempt was made to use the brush again, it wouldn't work. From that, I draw the connection of the airvalve not working from the cleaning, or the lack thereof. Which still brings up the question of how the contamination got into the valve to start with, it either came in from above, paint, solvent, etc. spilling in, or from below, the air source or through handling and cleaning.
Either way, the cause needs to be stopped, as well as the symptom.
Finding out how the brush gets cleaned may help diagnose All the problems.
I had a few customers and students who soaked the whole airbrush in cleaners, only to find that rather than removing the debris from the airbrush completely, they moved it, in two cases, they moved it into the air passage within the airbrush body itself. It was a nightmare to deal with.
I am the last person to argue against good thorough cleaning practices, but care needs to be taken when doing so.

Laquer thinner is fine on most packing and seals that were meant to be exposed to paint, but the trigger piston seal and the seals and packing of the airvalve were never meant or designed to be exposed to those elements.

I have had two airbrushes that have needed new airvalve assemblys or parts since 1973, both times, it was a case of things getting worn out by use. From the sounds of Toybot's initial message, this brush and user haven't been at it all that long. That model airbrush hasn't been around all that long, so I doubt it is a matter of age on the airvalve.

Toybot, when you have the airvalve assembled, and disconnected from the brush, but hooked up to the air, can you or do you get air coming through?

IF you keep the trigger and piston in the airbrush body, can you get air through the front of the airbrush by blowing through the opening where the airvalve was? If the answer is no, then you have a blockage problem in either the air passage, and or the nozzle cap.

Normally, air does not blow through the nozzle, when it does, it is blowing backwards, and causes bubbling in the paint reservoir (cup or bottle). Not good.

thanks guys. i really appreciate all your suggestions. I do think it's clogged in the air passage too. when I pulled out the valve completely, there was urethane up in there too...

If you have urethane paint in the air passage, you can try removing the air valve, and the rubber seal for the trigger piston, remove the nozzle, nozzle cap, handle, needle chuck, the chucking nut, the spring and adjuster, and the trigger itself. Basicly, you want to strip as much of the removeable stuff as you can.
Using a solvent proof container, prefferably metal, you can soak the airbrush in MEK, this will probably remove the enameled lettering on the side of the brush, but it will also break down the urethane paint inside the brush too. I'm talking about soaking just the airbrush body itself, not the other pieces. The MEK will destroy the rubber seals and pieces, laquer thinner would also probably damage or destroy those same pieces.

After it (the brush) has soaked for a while, try using a squirt bottle of MEK to flush the contaminants back out. Do the flushing several times. You're already making the mess, so you may as well be thorough. Test the squirt bottle with the solvent BEFORE you use it on your brush. You don't want the bottle to melt or break down on you, much less spraying that now ruined plastic into your airbrush. You can give the exterior a good scrub now too. make sure you scrub out the trough at the bottom of the paint reservoir (cup).

You can try this with laquer thinner first, it's safer, but a whole lot less potent.
The MEK is nasty stuff, you need to do this kind of thing wearing the proper protective gear, and in a well ventalated area, absolutely no flames, sparks, or other sources of ignition should be within shouting distance.

If you didn't submerge your brush before, then you have a major breach somewhere.

This kind of cleaning should only be done in the most extreme situations.
Your normal cleaning routine should not involve submerging the airbrush in anything.

If you are getting paint into the trigger well when you backflush, then it means your needle packing/seals are in need of adjustment or replacement.
If you are getting paint into the airvalve when you backflush, then you have performed an engineering miracle. It would mean that you had paint being forced back down the very same pathway that was carrying the air that would propel it, and at the same time.

When you backflush, you are pushing air, and hopefully paint/debris, back throught the nozzle, through the paint passage, and into the paint reservoir (cup or bottle). It is not flowing back down the air passage.

In my cleaning routine,I backflush all the time, be it with acrylics, enamels, laquers, or urethanes, and I have never had paint go backwards, against the wind, and into the airvalve.

Shy of using an airless spray gun, or a pressure pot, the paint is not pushed through the nozzle by air or compression, it is pushed by gravity and pulled by the mild vacuum created as the wind/air passes around the tip of the nozzle, and is forced through the tiny opening in the nozzle cap. That is why it takes more pressure to use a siphon feed brush than it does a gravity feed brush, it takes more air pressure to create a strong enough vacuum to pull the paint up from the cup or bottle below, and the thicker or heavier that paint is, the tougher it is to suck it up into the path of the air stream or path.

If the paint was pushed by the air all the time, you would have paint shooting or bubbling out of the reservoir all the time, like you do when your nozzle cap is dirty, or your nozzle is not clean or seated well.

More likely, you have gotten paint into the airvalve by submerging your brush, or you have somehow gotten paint into your air supply.

If you had paint going into the airvalve by way of the trigger well with the airbrush assembled, it would mean that you would have to have a really bad seal for the trigger piston, and be either really sloppy in your handling of the paint or airbrush, or a really bad needle packing/seal that would let the paint go past, and into the trigger well.

The severe leak of the trigger piston seal would be evident every time you push down on the trigger. You would be getting a jet of wind blowing up on your trigger finger(s).

Redneck, while the water will travel in that tiny gap, it still means that there has to be a gap to start with, and the viscosity and stickiness of the paint is much higher than the water you have, or at least I hope it is.

Redneck, ideally, the tolarance is 0. The needle bearing/packing/seal, should be doing a bit of squeegy action on the needle, scraping the paint off of the needle every time you pull the trigger back. Of course this will only hold true if your seal is in good shape, and it is tightened down properly. Too tight, and it is a fight to move the trigger/needle back and forth, too loose, and it lets paint back into the trigger well. There are tools made for adjustment and installation of these, but most people don't have them in their arsenal, they probably wouldn't get enough use out of them to justify the cost.

The two biggest killers of the seals/packing/bearing are crusty and or bent needles being pulled back through them. The hard, crusty paint acts like a rasp, or grinder, taking off material as it passes through. The bent needle scores the rubber or teflon on it's way through too.

The bent needle will also trash nozzles in a hurry, while not as quickly as it does the seals, it is another good reason for leaving the needle cap on the brush at all times.