H&S problem. Again!

[Gern]

Hi folks.

I tried to do some spraying with my H&S Ultra (2024 version) and got no air coming through the nozzle at around 20psi. I went all the way back to the compressor and checked everything in turn - hose connections, air valve into the A/B, the trigger with and without the needle and the needle movement. I get plenty of air everywhere along the system until I put the actual nozzle in place and the air stops. I have a 0.4 needle and a 0.4 nozzle (both checked with the band markings) and everything has been thoroughly cleaned and checked for any obstructions. I've also changed the seal on the nozzle for a new one and it still doesn't work.

OK I thought, I'll just use my Infinity. I've got exactly the same problem with that one using both a 0.4 and 0.2 needle/nozzle setup.

Both brushes worked fine until November when I first started to notice some problems. The only thing I have changed recently is I have stopped spraying Vallejo and I now use Tamiya acrylics thinned with MLT exclusively, and I use MLT to clean my A/B after spraying. I have an ultrasonic cleaner with a couple of squirts of liquid hand soap and that's worked fine for the last couple of years, although my A/B is stripped and cleaned in there probably only once a week.

I was using Tamiya acrylics thinned with X20A with no problems until the end of last summer, so the only thing that has changed is my use of MLT.

Any suggestions?

[BarryW]

Hi folks.

I tried to do some spraying with my H&S Ultra (2024 version) and got no air coming through the nozzle at around 20psi. I went all the way back to the compressor and checked everything in turn - hose connections, air valve into the A/B, the trigger with and without the needle and the needle movement. I get plenty of air everywhere along the system until I put the actual nozzle in place and the air stops. I have a 0.4 needle and a 0.4 nozzle (both checked with the band markings) and everything has been thoroughly cleaned and checked for any obstructions. I've also changed the seal on the nozzle for a new one and it still doesn't work.

OK I thought, I'll just use my Infinity. I've got exactly the same problem with that one using both a 0.4 and 0.2 needle/nozzle setup.

Both brushes worked fine until November when I first started to notice some problems. The only thing I have changed recently is I have stopped spraying Vallejo and I now use Tamiya acrylics thinned with MLT exclusively, and I use MLT to clean my A/B after spraying. I have an ultrasonic cleaner with a couple of squirts of liquid hand soap and that's worked fine for the last couple of years, although my A/B is stripped and cleaned in there probably only once a week.

I was using Tamiya acrylics thinned with X20A with no problems until the end of last summer, so the only thing that has changed is my use of MLT.

Any suggestions?

Yes, clean it again. And again if necessary.

You might want to try back flushing with Mr Tool Cleaner which is very powerful stuff. The seals in H&S airbrushes can stand it. Have you also really got into the threads with a cotton bud? Use MTL there too. As for the nozzle, there are dental products made from paper that really get into small spaces such as a nozzle and won’t damage it. You can find the via Google, they come in many sizes.

[Tim Marlow]

Couple of things to look at

When the trigger is fully off can you see the needle protruding from the nozzle? If you can then the nozzle isn’t blocked. Worth checking this.

Might sound dumb, but the Chuck nut is done up isn’t it? ie, when the trigger is moved backwards the needle does move with it?

Lastly, if the nozzle was blocked, when you start the airflow and move the trigger backwards there should be air appearing in the paint cup (like you get when putting your finger over the end of the brush). Does this happen?

[Tim Marlow]

Also, these are not airbrush models I own, so, are they solid stainless or chrome plated brass bodies? Ultrasonic cleaning is pretty abrasive. Just wondering is the Ultrasonic cleaning has disrupted any plating and blocked the air pathway somehow?

[Gern]

OK guys. Thanks for all the suggestions. I wanted to try Tim's suggestion of testing the backflush, so I swapped the ordinary nozzle cap for a pinchtip cap. Yaaayyy! My Ultra is back in working order! I have a couple of the 'normal' needle caps so I can only assume I fitted the wrong cap.

Got to try swapping the caps on my Infinity and see if I can sort that one - but there's no rush now I got a working A/B.

PS Barry - I did give everything a thorough clean and used one of those tiny reamers on the nozzle. It didn't work because I obviously had the wrong cap. I will see if I can get hold of some of that Mr Tool Cleaner for future use.