Iwata HP CR flow issue

R

RockyV

Guest
Hey everyone, I wanted to run an issue I'm having by you. I'm using an Iwata HP CR .5mm airbrush with water based acrylic paint at about 22psi. However, I'm not getting good paintflow. When I press the trigger, air comes out fine. However, when I pull back for paint, I don't get anything unless I pull all the way back, and then I get a big and messy blast. Also, as I bring the trigger back forward, it seems like it will shoot out a puff of paint. I've broken the airbrush totally down and thouroughly cleaned it, and I'm pretty sure I can't see any debris clogging it. I've also pulled the needle nozzle off and cleaned that. Still the problem persists. I don't think it's a paint consistency issue as I've been spraying for a while and have not had a problem. Just started last night. I'll call Iwata tomorrow, but I figured I'd ask here in case someone has seen this before and knows how to fix it.

Thanks!
 
It's quite common Rocky and definitely a cleaning issue, although you think it's clean there is something stuck in the nozzle, if there isn't it could be debris in the space between the nozzle and cap, try soaking the nozzle and cap in some cellulose thinners or acetone for about 15 minutes and then blow through with normal cleaner.

Hope this helps, if you don't already do it I recommend straining your paint.
 
You are not saying what paints you are using or if and by how much you are reducing. 22psi is pretty low and paint needs to be thin. The blob that comes out when you return the needle is because the paint sits in the nozzle but because there is not enough air, it does not spray out. When returning the needle you are pushing the paint through the nozzle and there it meets the air and a blob sprays.
 
If it's normal hobby paint that you've diluted to spray though the brush then I'd suggest the psi isn't high enough and the paint not diluted enough...or as stated above, wrong paint for purpose

What are you painting on? Brickwork/canvas/clothing?
 
Thanks for the replies! It's Vallejo water based acrylic for scale models. I'm not sure it's a thinning problem. I am using reducer, and it's been spraying fine for a while at the amount I've been reducing. It's possible I am not using correct psi for the paint however, I'll try raising it and maybe reducing a bit more as well. Thanks for all the help folks!
 
Hey folks, just an update. I've kicked the PSI up to 45 and that seems to help a lot. I think this formula just needs more power.
 
There are a few here who use vallejo so they can probably comment better. 0.5mm seems a huge size for modelling, what are you painting? How about popping along to the intro section and say hi... where are you from, what you paint, experience, etc... heres the link.

http://www.airbrushforum.org/introductions/

Cheers Mark
 
0.5 is basically just for priming and base coating. :) I have a 0.2 I use for other stuff. I'll pop over to the intro forum and say hi though! Thanks!
 
Hey Rocky :) The symptoms you describe are classic dirty nozzle issues. Nozzles are a bar steward to clean. You can clean them, they can seem spotless, but they are tricksy, and paint hides in there. The needle is then not seating properly which affects the spray pattern, and doesn't allow paint to come out right away, but causes it to back up, until it is finally able to get out - giving a big blow out all at once. If you unscrew your needle chuck and very gently move your needle in and out you can sometimes feel if it seems spongy, or sticky, that is one sign of a dirty nozzle. You can also sometimes see if your needle isn't sticking out as far as it should, or if you spray a dot, it could spray unevenly, or spider in one area. You could also be getting bubbling in the paint cup as air is getting forced back (this also happens if air is leaking from threads on the head to, so make sure your seals are good) The blow outs, or blobs at the end of strokes you already know about :) If it was spraying well before but isn't now, and nothing has been damaged, then it really does point to a nozzle issue.

45psi is ok for priming and basecoating, though reduced it shouldn't need to be that high (I haven't used that particular brand of paint before mind you), especially through a .5 nozzle. To use your.2 nozzle for detail, you are going to want to be somewhere between 10-25 psi depending on how fine you need to work, to get the control and minimise overspray. So I would play around and experiment until you get your air/paint/reduction just right, as if it isn't spraying through your .5, there's no way the .2 will work. So make sure the nozzle really is clean, and also examine it with a magnifying glass or similar for cracks or other damage, then really spend some time getting it dialed in. This will also help reduce the possibility of future blockages, as when it all flows well it is way less likely to block in the future. :)
 
Thanks for the reply! Do you have any tips on cleaning the nozzle? I removed it while I was giving it a good clean, carefully cleaned the inside and looked through it and I could not see any sort of debris in there, I also cleaned the brush itself with a dental brush. Without the nozzle on, if I pour some cleaner into the cup it runs out of the airbrush freely. I will reinspect it for damage when I get home tonight, but I did not see anything obvious when I checked last time :)
 
There are some great youtubes on cleaning and maintenance. This is a good one for starters.

You don't need to strip the brush down often.

 
Thanks for the reply! Do you have any tips on cleaning the nozzle? I removed it while I was giving it a good clean, carefully cleaned the inside and looked through it and I could not see any sort of debris in there, I also cleaned the brush itself with a dental brush. Without the nozzle on, if I pour some cleaner into the cup it runs out of the airbrush freely. I will reinspect it for damage when I get home tonight, but I did not see anything obvious when I checked last time :)

The reason I don't like any of the guns that does not easy access to the back of the nozzle is you can easily loose the nozzle en you can just as easily break off the threads when attaching again.
 
Yea, it does seem like a bit of a pain. Out of curiosity, what do you use?
 
Yea, it does seem like a bit of a pain. Out of curiosity, what do you use?

Eclipses and Micron and Harder & Steenbecks. With the Micron you can remove the whole head and get in that way and the rest has drop in nozzles.
 
That does sound a bit easier. If I get back into the market for another brush I'll have a look at those.
 
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