Paint only pushing the trigger



Hello Everybody!

Recently i got myself a second hand Iwata HP-B (classic i think).
My very first duel action airbrush (i started with a Hansa 108, which works great but it doesn't teach me the basics of most airbrushes).

But im encountering some strange problems that i cant seem to fix.

When i remove the needle cap (that protects the nozzle) and i push the trigger only air comes out as expected. When i put the cap back on a small stream of paint is coming out. when i unscrew the cap a bit the paint stops but bubbles start to arise in the cup.

What i tried so far:
  • Lots and lots of googeling / youtubing on these issues
  • Striped the airbrush and put the stuff in airbrush cleaner (Medea). soaked a hour and cleaned all parts with 98% alcohol for good measure. After this i lubed the airbrush with some acid free silicon grease
  • Ive added special tape on several threads in the hope to stop any air leaks
  • Cleaned the nozzle several times now
  • Tightened the screw inside the airbrush which holds the needle (just before the cup)
  • Checked the nozzle for damage with a magnifying glass (when the cap is not on, there is no problem so i suppose the nozzle is alrigt)
  • tighten everything that can be rotated
This is all i could find online and im out of options to get my new very shine toy to work nicely.
I really hope i havnt bought a broken airbrush :(

Is there anything else i could try?

Thank you very much for your help and answers!
Thank your for the reply!

The nozzle is screwed on quite well so im not sure if this is the issue.
Im not quite sure of what i should take a photo of, would you like to see the nozzle ?

#Edit -1
Added photo of the nozzle

Ps: as stated in the starting post, ive cleaned the airbrush several times. i think its quite clean but i could be wrong tough :)
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It may be the wrong nozzle in it. I know the changed the thread size on the newer nozzles and if it an older brush they may have put in the newer one.

Paint on
Yes i have come across this difference on part sites i found.
Any idea how i can check if this is the case?
That pic is of the tip and needle. It is a 3 part system. You need the cap on to allow the air to flow past the tip and pull the paint out along the needle (when the needle is brought back allowing paint out). When the cap is on, you should have a space around the tip to allow the air to flow. Each 3 parts should match ....I have a Talon that has 3 different needle setups and the components are matched...each size has needle, tip and cap. If you mix these up, it will not work very well...
Hope this makes sense....
Hey Vasquo. Sorry you're having issues. Can I just clarify something I may be misunderstanding. When you say you remove the needle cap that protects the nozzle, taking the needle cap off just exposes the needle, removing the next part as in the photo, is what exposes the nozzle. That part also funnels the air over the needle, so if its that part you are taking of, it wont draw up paint. Sorry if I'm getting the wrong end of the stick :)

With a second hand brush its possible parts could be wrong as mentioned or the nozzle could be flared or needle and nozzle have some wear. Also although you have soaked and cleaned, nozzles in particular can be stubborn, and not knowing what the previous owner sprayed through, it may be that your cleaner has gummed up any residue, rather than clean it out. You may be able to tell by undoing your needle chuck and gentle moving your needle I and out, if it feels spongy or sticky then it is blocked/ dirty.

As you are in the Netherlands, if you still have issues, you could contact lion-art, a very helpful supplier who is a good egg and may be able to offer further suggestions or advice on parts if needed.