Airbrush bubbling back in the trigger well

[Stevekir]

After cleaning the airbrush and assembling it again, I blow some airbrush cleaner (or water) through to check the flow. The cleaner (or water) bubbles up in the well containing the trigger (NOT in the colour cup which seems to be the usual beginner problem).

By cleaning I do this:

Clean the cup with a good quality paper towel, add some cleaner (or water) to the cup and brush the bottom of the cup, pour out the mixture and repeat perhaps another twice until clean;

Add Vallejo "Airbrush Cleaner" (or water) to the cup and blow compressor air through, repeating until it blows clean;

Remove the nozzle and the two caps and withdraw the needle from the front and thoroughly clean it;

Put the nozzle and the two caps in cleaner, agitate and leave to soak for about 10 minutes or more while continuing to clean the airbrush as follows;

Insert the little bottle brush into the passage between the front and the bottom of the cup and add cleaner to the cup;

Agitate the brush in and out, pushing it in a little so that its tip disappears beyond the bottom of the cup (by about 5 mm). Repeat cleaner and brush until the brush shows clean;

Use the little bottle brush on the nozzle and the two caps to thoroughly clean them;

Re-insert the needle from the front and reassemble the airbrush and confirm a good flow with cleaner (or water);

At this stage cleaner (or water) immediately bubbles up in the well containing the trigger. I have to remove the trigger and dry the well.

This bubbling up in the trigger well has now happened four times in a row, and once about several cleanings ago, since I got the AB four weeks ago (a good quality one with PTFE seals or whatever they are called, the good ones).

I have noticed that when inserting the needle from the front there is a small resistance when it starts to enter the end (nearest the front) of the well containing the trigger. Presumably there is a seal there. Therefore, when cleaning as above, to prevent the cleaner (or water) running back into the trigger well (the needle is no longer there to block the seal) I keep the front of the airbrush pointing downwards at all times when cleaning. But the cleaner (or water) still bubbles up in the trigger well. There is definitely no sign of water in the hose or the compressor air supply (and in any case the problem occurs only immediately after cleaning).

Could you please tell me why this is happening and how to prevent it?

Thanks.

 

[Danny]

Hi Steve...being a newbie to air brushes Im not in the position to offer any solutions to your bubbles in the trigger well, but I was informed by the salesman who demonstrated and sold me the airbrush, that the needle must always be replaced from the back and not the front. This Ive been doing and have had no problems at all... I assume one of us is wrong, so we wait with anticipation on an expert coming to keep us straight..

Danny

 

[ojays]

After cleaning the airbrush and assembling it again, I blow some airbrush cleaner (or water) through to check the flow. The cleaner (or water) bubbles up in the well containing the trigger (NOT in the colour cup which seems to be the usual beginner problem).By cleaning I do this:

Clean the cup with a good quality paper towel, add some cleaner (or water) to the cup and brush the bottom of the cup, pour out the mixture and repeat perhaps another twice until clean;

Add Vallejo "Airbrush Cleaner" (or water) to the cup and blow compressor air through, repeating until it blows clean;

Remove the nozzle and the two caps and withdraw the needle from the front and thoroughly clean it;

Put the nozzle and the two caps in cleaner, agitate and leave to soak for about 10 minutes or more while continuing to clean the airbrush as follows;

Insert the little bottle brush into the passage between the front and the bottom of the cup and add cleaner to the cup;

Agitate the brush in and out, pushing it in a little so that its tip disappears beyond the bottom of the cup (by about 5 mm). Repeat cleaner and brush until the brush shows clean;

Use the little bottle brush on the nozzle and the two caps to thoroughly clean them;

Re-insert the needle from the front and reassemble the airbrush and confirm a good flow with cleaner (or water);

At this stage cleaner (or water) immediately bubbles up in the well containing the trigger. I have to remove the trigger and dry the well.

This bubbling up in the trigger well has now happened four times in a row, and once about several cleanings ago, since I got the AB four weeks ago (a good quality one with PTFE seals or whatever they are called, the good ones).

I have noticed that when inserting the needle from the front there is a small resistance when it starts to enter the end (nearest the front) of the well containing the trigger. Presumably there is a seal there. Therefore, when cleaning as above, to prevent the cleaner (or water) running back into the trigger well (the needle is no longer there to block the seal) I keep the front of the airbrush pointing downwards at all times when cleaning. But the cleaner (or water) still bubbles up in the trigger well. There is definitely no sign of water in the hose or the compressor air supply (and in any case the problem occurs only immediately after cleaning).

Could you please tell me why this is happening and how to prevent it?

Thanks.

Can you post some pics of your AB..

I agree with danny, some require you to insert the needle from the back! Inserting the needle incorrectly can damage/stretch the seals allowing incorrect (leaks) flow of air internally .

Gregg

 

[Gomer Pyle]

Hi Steve! The seal within the AB housing, that sits between the air-supply and the paint-cup, could very well be either damaged/worn or covered in dried paint with cracks in it. I usually clean the housing and that particular seal using windex and one of those little twisted toothbrushes that look like bottle cleaners. I use these as the wire that tie the brush, seems softer and less damaging than what I found elsewhere. Mind you I haven't tried the purpose-made AB cleaners they might do even better. You could give it a try or go all the way and visually inspect the seal, which means more dis-assembly.

/Daniel

 

[m1ks]

Most importantly, does this continue after cleaning it/drying it, (the liquid in the trigger well), I.e. does it then get more liquid in there?

If so it's leaking back past your seal.

If not, it's getting in there when you're cleaning it, don't worry it won't hurt.

If it is leaking a good clean of the needle and maybe nipping up the packing screw will cure it. Will post a link to my how to strip video when on the pc later.

 

[Stevekir]

It does not continue after drying the trigger well. I was guessing that it was getting there in some way during cleaning, the needle not being there to block the seal at the trigger well. Many thanks (it is a brand new AB).

On another question: having sprayed Vallejo gloss varnish followed by thorough cleaning and then using Model Air paint, the AB blocked within a few seconds of brushing with the paint, so I cleaned it thoroughly as described in my post. The same happened again when I sprayed with paint. I cleaned yet again, this time leaving the three nozzle parts in the Iwata/Medea Brush Cleaner for several hours. I am unable to do any more airbrushing for a couple of weeks (the spare bedroom has been invaded by family) but if the blockage persists should I consider an ultrasonic cleaner? If so:

== Amazon are selling a simple one, the JPL Ultra2000 at £24.99 which is big enough for an airbrush. Would that be the sort of thing to go for?

http://www.amazon.co.uk/JPL-2000-Compact-Ultrasonic-Cleaner/dp/B002WBKLBS/ref=sr_1_5?ie=UTF8&qid=1362581488&sr=8-5

== Is it safe to put the main body of the AB in an U/S cleaner, (as well as the nozzle and its bits, and the needle and trigger)? (My AB has (is it Teflon?) seals, not the cheaper rubber ones.

Thanks.

 

[geegad]

what make airbrush is it

 

[Stevekir]

what make airbrush is it

Its Harder & Steenbeck Infinity CR+, 0.4 mm nozzle/needle.

 

[cutandfold]

I have an Infinity in my collection...no different really than any other airbrush.

Needles are removed and replaced from the rear, where your locking nut is.

The taper of the needle will also allow it to enter and pass thru the packing (within the body) easier.

If paint and/or air is being forced back through the airbrush (you see bubbling in the paint cup and/or

at the trigger location)...then the airbrush is blocked.

The tip is clogged with paint or debris...or...the air passages in the tip cap/housings are plugged.

I always teach "clean it, clean it...and then clean it again. If you think your airbrush is clean...its not."

The seals and packing in the airbrush can only stand up to limited pressure. If something is clogged

then paint and/or air will easily "back up' into the airbrush. It is very rare for those packings to get

damaged, but if you have been pushing that needle in from the front, you may have damaged the seal.

I would start by assuming its just a clogged airbrush. Its a more common issue.

Assume the airbrush needs to be rechecked and more thoroughly cleaned.

Check those tiny air passages in the tip cap and air housing. Use fine wire or a tip cleaner to make

sure the passages are clear. (A tip cleaner is the same thing as used to clean welding torch tips)

 

[Ian M]

Just sounds like run back to me. As you say it only happens when you clean it and you have had the needle out. It happens with mine as well some times.

Being aware of this I always point the stripped down airbrush down blast it through a couple of seconds and leave it 'nose down' while I sort out the tip and nozzle.

Also as an extra precaution, if I am switching from, say a water base to an oil or cellulose base I give it a quick flush with a few drops of the appropriate thinner. Just in case there is a bit of something hiding in a corner some place.

Ian M

 

[cutandfold]

Do you clean your needle in any way?

other than removing obvious paint from anywhere on the needle, you should not do anything else to it.

...except polish it.

I used to use cloths, steel wool and even fine sandpapers to clean my needles.

This was a big mistake because you are creating scratches in the needle which

can gather paint and residue.

And this affects the quality of the seal between the needle and

packing inside the airbrush.

Needles should be polished as smooth as possible to allow for a smooth glide

and the best seal. Needle "lube" is also a good idea.

Use only ultrafine sandpapers and polishing compounds.

 

[tecdes]

I wonder Steve if you are leaving the nozzle cleaning to last. If so then the paint in the nozzle has time to solidify.

After withdrawing the needle backwards a fraction I remove the nozzle & shield & then dunk it in an eggcup full of Vallejo Airbrush Cleaner & let it soak there until I have cleaned the reminder of the brush.

Before refitting I sluice in water then sight down the needle against a lit up piece of white paper. This will tell you if the nozzle has a nice clean orifice.

If you have any stubborn bits left in there use a reamer obtainable from airbrush suppliers. But as my supplier said use it gently as it is very easy to damage or break the nozzle at the pointed end. I used it a number of times until I got into the above routine.

Good idea to obtain a set of seals which are very little in cost for quick turn about.

Laurie

 

[Stevekir]

Thanks folks. I seem to have mastered airbrushing colour. I can get a good even result with only a very few blockages which, if they occur, I get rid of by increasing the air pressure to 45 PSI and repeatedly pulling the trigger back, then forward. But blockages are rare now. I first clean the paint cup and the area under it, then the nozzle and nozzle cap by soaking in Vallejo Airbrush Cleaner for about 5 minutes, while using the Harder & Steenbeck bottle brushes on the passage between the nozzle area and the trigger, then clean the nozzle with a inter-dental brush and the nozzle cap with a pointed cotton bud available from model shops. I inspect both with a mag. lens against a light. The needle is wiped twice with a paper towel and Airbrush Cleaner. Under a mag. glass the needle always appears clean and shiny.

I then put the whole airbrush and its parts into my new ultrasonic cleaner, the JPL Ultra2000 mentioned earlier (although I seldom remove the trigger and the bits that go from there and the needle chuck, and I have never disassembled the air supply area.) If I do a colour change and continue to spray immediately, I don't clean (apart from the cup), just shoot some AB cleaner or thinner.

H & S tell me that it is safe to use an ultrasonic cleaner every time, if you want.