Airbrush - Siphon type, spills when changing pots

[RBTKraisee]

Hi all, a bit of a dumb issue, but I definitely need some advice from more experienced hands!

 

I've picked up an Iwata Revolution HP-BCR siphon airbrush and started to experiment with it yesterday evening.   But when I go to change the pot underneath it, a small gush - half-a-dozen big droplets - of fluid spills out onto the floor.

 

I was using some Model Master enamel, thinned about 50/50 with lacquer thinner.   The spill happened twice in a row, yet thankfully nothing has been damaged (dining room table, chairs, trousers, shoes etc), but if this continues it's only a matter of time before I splatter something valuable and my better-half skins me for it.   So I erred on the side of caution and stopped until I could consult with more knowledgeable experts.

 

Has anyone here ever experienced any similar issues?   And if so, what did you do in terms of a reliable solution?

 

Thanks in advance, for any advice!

 

Ross.

[JeffP]

Where from?

If it's from the pipe that goes into the pot, unscrew the pot, withdraw the pipe until it's clear of the LIQUID underneath, but NOT clear of the pot, and gently tap it on the pipe to encourage any fluid trapped to drain into the pot.

I'd also have a paper towel ready so that the pipe can then drip onto it if necessary when transferring to a new pot.

[Mick Bonwick]

All airbrushes, top feed, side feed and bottom feed, will have fluid in the body between the paint receptacle and the nozzle when you stop spraying. With top feed and side feed that fluid stays where it is until you spray it out, but with bottom feed it does what fluids do - take the path of least resistance to do what gravity tells it to do.

 

The best way of dealing with this is to continue spraying (onto a paper towel or similar), while removing the bottle, until all of the fluid in the body has been expelled. You may have a seal that is not airtight at the front of the airbrush that is contributing to your problem, so I suggsest that you ensure that all components are tightened fully, but not overtightened.

[cctransuk]

3 hours ago, RBTKraisee said:

Hi all, a bit of a dumb issue, but I definitely need some advice from more experienced hands!

 

I've picked up an Iwata Revolution HP-BCR siphon airbrush and started to experiment with it yesterday evening.   But when I go to change the pot underneath it, a small gush - half-a-dozen big droplets - of fluid spills out onto the floor.

 

I was using some Model Master enamel, thinned about 50/50 with lacquer thinner.   The spill happened twice in a row, yet thankfully nothing has been damaged (dining room table, chairs, trousers, shoes etc), but if this continues it's only a matter of time before I splatter something valuable and my better-half skins me for it.   So I erred on the side of caution and stopped until I could consult with more knowledgeable experts.

 

Has anyone here ever experienced any similar issues?   And if so, what did you do in terms of a reliable solution?

 

Thanks in advance, for any advice!

 

Ross.

 

You use an airbrush in the dining room?!?

 

John Isherwood.

[RBTKraisee]

Hi John,

Our place is pretty small so I don't really have much choice.   Florida humidity makes doing it outside impossible, and we don't have a shed/garage.   The one bedroom is carpeted, so the dining room with it's tiled floor get used when everyone else is out for the afternoon and I can air the place for an hour after I finish.   I also use an R95 full mask and a fold-away spray booth, with extractor.   The arrangement has allowed me to use rattle cans before, but this spillage issue with the airbrush is a new phenomenon for me.   Even my first practice run yesterday showed me that the airbrush instantly produced better coats than the rattle's ever do, so I really want to be able to use it - without damaging anything else.

 

Ross.

[RBTKraisee]

JeffP; It didn't look like it was from the pipe on the top of the bottle, it looked like it was residual fluid that had been pulled into the airbrush, but hadn't yet made its way out the nozzle.   And paper towels - check.   On my first practice, I certainly noticed how messy this can get    Makes almost as much mess as my resin 3D printer does!

 

MickB; That makes sense.   I'll give the spray-while-removing technique a go (with more paper towels) and see if it fixes this.   I also took the whole unit apart last night to see if there were any issues - and to get more familiar with all the bits, and I watched a few vids on how to clean & maintain the unit properly.   Everything seemed firmly hand-tightened, and I couldn't detect anything out of alignment, so I'm guessing the seals were probably okay.   But I'll keep an eye out for loose bits as a potential issue down the road - thanks for the heads-up on that.

 

This advice is very much appreciated.   I'll let you know how my next run goes!

 

Ross.

[RBTKraisee]

Hi John,

Our place is pretty small so I don't really have much choice.   Florida humidity makes doing it outside impossible, and we don't have a shed/garage.   The one bedroom is carpeted, so the dining room with it's tiled floor get used when everyone else is out for the afternoon and I can air the place for an hour after I finish.   I also use an R95 full mask and a fold-away spray booth, with extractor.   The arrangement has allowed me to use rattle cans before, but this spillage issue with the airbrush is a new phenomenon for me.   Even my first practice run yesterday showed me that the airbrush instantly produced better coats than the rattle's ever do, so I really want to be able to use it - without damaging anything else.

 

Ross.

[RBTKraisee]

Drat. After another good painting session, I tried detaching the bottle while still spraying and got much the same result - maybe one or two fewer droplets.   Image attached.

 

I guess I'll just have to expect it, always do it over something non-valuable, and keep plenty of paper towels handy

 

If anyone can think of anything better, please do chime in!

 

Ross.

[K14]

Have you tried a quick backflush before removing the bottle? That **ought** to blow the excess paint back into the bottle.

[RBTKraisee]

Backflush?   Not familiar with airbrush lingo yet, I'm guessing you mean covering the nozzle so it can only blow back into the bottle?   I've seen some folk doing that for mixing paint in gravity fed airbrush cups.   It sounds like a good idea to try.   I'll let you all know what happens tomorrow :)

Thanks,

Ross.

[RobjUK]

That airbrush looks very similar to one I have; press the button/lever for air control & pull for paint flow?

 

If so, try pulling the level full back without pressing for airflow, so air can get back into the paint channel through the nozzle and allow the pickup tube to drain back?

 

 

[RBTKraisee]

So...   I thought this was a great way to prevent my spill issue, but after giving it a try, I will NOT be recommending trying a backflush with a siphon airbrush.

 

All I can say is, thank heavens that we had a cold front come through my area last night, and I was able to go outside for today's painting session.

 

I did an initial paint run trying to paint some wire/latex trees that I'd made. Everything worked great, and when I tried the backflush it seemed to work well - no spill. Woo hoo!

 

What I didn't pay attention to at the time, is that almost all the green paint had been used and the bottle had hardly anything left in it. I then went back to my blue test parts, cleaning the brush in between, and aiming to get a few bits of coverage that I missed last time. The painting went fine. Disconnecting the blue paint bottle afterwards, errr, not so much...

 

Y'see, unless you know what you're doing (I sure don't, total newbie here) and are extremely gentle with the backflush, you might end up partially pressurizing the paint bottle.   Turns out that the small vent in the lid can get partly clogged with dried paint during the session, so the resulting hole just isn't always enough to dissipate the backflush pressure quickly. You can see where this is going, right?

 

So, unless you wait for a few minutes, you still have plenty of pressure in the bottle when you disconnect it. The resulting jet of paint streamed 6ft across the yard! 

 

I didn't stop to take a picture before cleaning up my better half's plant pots and tiles, but after that cleanup I took a picture of the overspray catch box I was using and you can probably see from the state of it, just how much paint went flying. Note the brick on the top. The paint got two feet above it!

 

I can laugh about this because it didn't do any permanent damage to anything, but I probably won't be giving that particular solution another try any time soon and painting indoors is likely to get nixed going forward!

 

Ross (still with blue fingers).

Edited April 11, 2020 by RBTKraisee

[Mick Bonwick]

Ah! Could this be the reason the paint doesn't fall back into the bottle in normal use? Does the same thing happen if you use plain water?

[Torper]

This airbrush receives generally excellent reviews.  You say that you "picked up" the airbrush which would suggest that you got it second-hand, maybe cheaply.  I wonder if it came to you with an existing fault which the seller did not bother disclosing to you?

 

DT

[RBTKraisee]

6 hours ago, Mick Bonwick said:

Ah! Could this be the reason the paint doesn't fall back into the bottle in normal use? Does the same thing happen if you use plain water?

Hi Mick,

Neither water nor Medea Airbrush Cleaner seem to do the same thing as the paint, no.   The only difference is that the cleaner is in the Iwata bottle that came with the airbrush, where the water and all the paint is in 3rd party bottles   The two bottle types seem pretty similar in design.   Visually, the feedlines look to be the same internal diameter, the vent holes look to be about the same too - they are just from a different manufacturer.   They got 4.5 stars/59 reviews.

 

Hi Robj,

That's a good idea, and seems fairly low-risk   I'll give it a try later today and report back.

 

Hi Torper,

Bought this airbrush brand new from Hyatt's in Buffalo, NY through Amazon.   Since this spill issue started, I have taken it completely apart (followed instructions in an Iwata deep cleaning vid) and everything seems to fit perfectly and be in good order - at least to my untrained eye.

 

Ross.

Edited April 12, 2020 by RBTKraisee

[Mick Bonwick]

OK. Next idea - is your paint too thick, thus not passing freely through every aperture? If water works OK then it's probably not an airbrush fault. When the 'crazy paint spray' happens (all over everything) is the ventilation hole in the bottle lid completely clear, i.e. not restricted in any way by dried paint?

 

Try all the tests using the same bottle (the Iwata one). Start with plain water, then move to airbrush cleaner and finally to plain thinners. If all those work OK, then start with a mixture of five drops of thinners to one drop of paint, then five drops of thinners to two drops of paint and so on . . . . . .  .

 

[RBTKraisee]

21 hours ago, RobjUK said:

That airbrush looks very similar to one I have; press the button/lever for air control & pull for paint flow?

 

If so, try pulling the level full back without pressing for airflow, so air can get back into the paint channel through the nozzle and allow the pickup tube to drain back?

 

 

Robj,

I just tried this technique a couple of times and it appears to work!

 

Thank you!

 

Ross.

Edited April 12, 2020 by RBTKraisee

[RBTKraisee]

52 minutes ago, Mick Bonwick said:

OK. Next idea - is your paint too thick, thus not passing freely through every aperture? If water works OK then it's probably not an airbrush fault. When the 'crazy paint spray' happens (all over everything) is the ventilation hole in the bottle lid completely clear, i.e. not restricted in any way by dried paint?

 

Try all the tests using the same bottle (the Iwata one). Start with plain water, then move to airbrush cleaner and finally to plain thinners. If all those work OK, then start with a mixture of five drops of thinners to one drop of paint, then five drops of thinners to two drops of paint and so on . . . . . .  .

 

Mick,

While Robj's suggestion might be the operational fix I need to continue working without problems, I still want to try to figure out what was the underlying cause for the disconnection spills, so I can avoid the issue in the future.

 

I don't *think* the paint is too thick.   It was mixed 50/50 with lacquer thinner and appears to have the milky consistency that I've seen in multiple youtube vids.   The original paint out of the pot seemed to flow perfectly normally too, so I don't think the source was in poor shape either.

 

Certainly for the spectactular 'gusher' event, the vent hole had definitely become restricted by some dried paint and that was clearly a contributing factor to retaining pressure for a short while after backflushing.   The vent hole wasn't completely closed, but was perhaps 1/4 the normal diameter - and that was enough to allow the pot to pressurise.   I've now taken to using a small nail, the right size for the hole, to keep it closed when in storage, but removed just before use - it helps to prevent the hole getting clogged-up.

 

I'll try to do a full battery of these "thinning tests" this afternoon (on both bottles - if I have enough of the blue paint) and I'll let you know the results.

 

Ross.

Edited April 12, 2020 by RBTKraisee

[RobjUK]

I'd say it is inherent with the airbrush design?

 

When you use it, paint is pulled up out the container to the nozzle. The pick-up pipe then stays full of paint when you release the trigger.

 

Take the container off and you open the bottom of the full pickup pipe - allowing air back in and the paint out.

 

Letting air in via the trigger first, allows the pickup to drain back before the bottom end is opened up.

[cctransuk]

8 minutes ago, RobjUK said:

I'd say it is inherent with the airbrush design?

 

When you use it, paint is pulled up out the container to the nozzle. The pick-up pipe then stays full of paint when you release the trigger.

 

Take the container off and you open the bottom of the full pickup pipe - allowing air back in and the paint out.

 

Letting air in via the trigger first, allows the pickup to drain back before the bottom end is opened up.

 

I too think that this is getting out of proportion - a problem / solution is being sought that doesn't exist.

 

Detach the airbrush from the jar slowly and carefully - any paint remaining in the airbrush should drain back into the jar when air is admitted. If the two are separated too quickly,the jar is not there to receive the paint - cue spilled paint. As has been pointed out, the 'drain back' can be hastened by letting air in via the trigger.

 

All forms of painting can be messy - hence the usual practice of avoiding doing it in the domestic environment. If climactic conditions are unsuitable for outdoor painting, wait until they are, and do something else. Patience is an essential ingredient of railway modelling.

 

John Isherwood.

[RBTKraisee]

Quite unexpectedly work has totally slammed me, so I've only done one set of tests on this so far and don't have any conclusive results yet. I'm hoping to get a chance to get back to this and get a final conclusion over the weekend, if the weather allows and work doesn't need me to give up my weekend too. Whatever happens, I'll get there in the end.

 

Ross.

[RBTKraisee]

So, the push at work finally wound down and I managed to get a few hours this afternoon out on the patio, in the wonderful Florida spring weather, playing with my airbrush!

 

The test process involved five different thinning percentages, starting at ~30%, increasing at about ~10% per try and ending at ~70% thinner.   And I tried each of the them three times in a row, always doing it the same way - spray something and immediately try to disconnect the bottle within about 5 seconds of the last spray job.

 

I did a couple of extra tests here and there, where I tried waiting two minutes before removing the bottle, to try to give the paint time to run back into the bottle of its own accord.

 

And I ran an extra test on each cycle, using Tim's suggestion above, of opening the valve without airflow, holding it for just a few seconds to allow the paint to run backwards into the bottle, and then disconnecting the bottle immediately after.

 

I did each test cycle a total of six times, with six different colours; three Vallejo acrylics (one was a primer) and three Model Master enamels (no primers).

 

While not every test was 100% consistent, I did managed to get enough information for me to answer the fundamental question to my own satisfaction.

 

The results are quite simple, and in hindsight, fairly obvious:

 

1) Regardless of acrylic/enamel, the thinner the paint is, the more likely it is to spill back down the feedline as soon as the bottle is removed.

 

2) It doesn't seem to matter how long you wait before disconnecting the bottles, the paint does not want to flow back into the bottle without active encouragement.

 

3) Tim's approach of opening the paint valve without air pressure, works in nearly every case - Thank you Tim!    I only had one single instance where that technique didn't work, and that was with a medium thinned (~50%) acrylic black primer that dropped a single droplet out about 10 seconds after disconnecting the bottle, as I was getting my cleaning gear ready between paint change-overs.   Thankfully it hit the tiles in the yard and was easy to clean up.

 

So thanks to everyone for your suggestions and insights!   I'm a very happy airbrusher, once again!

 

Ross.

[cctransuk]

10 minutes ago, RBTKraisee said:

So, the push at work finally wound down and I managed to get a few hours this afternoon out on the patio, in the wonderful Florida spring weather, playing with my airbrush!

 

The test process involved five different thinning percentages, starting at ~30%, increasing at about ~10% per try and ending at ~70% thinner.   And I tried each of the them three times in a row, always doing it the same way - spray something and immediately try to disconnect the bottle within about 5 seconds of the last spray job.

 

I did a couple of extra tests here and there, where I tried waiting two minutes before removing the bottle, to try to give the paint time to run back into the bottle of its own accord.

 

And I ran an extra test on each cycle, using Tim's suggestion above, of opening the valve without airflow, holding it for just a few seconds to allow the paint to run backwards into the bottle, and then disconnecting the bottle immediately after.

 

I did each test cycle a total of six times, with six different colours; three Vallejo acrylics (one was a primer) and three Model Master enamels (no primers).

 

While not every test was 100% consistent, I did managed to get enough information for me to answer the fundamental question to my own satisfaction.

 

The results are quite simple, and in hindsight, fairly obvious:

 

1) Regardless of acrylic/enamel, the thinner the paint is, the more likely it is to spill back down the feedline as soon as the bottle is removed.

 

2) It doesn't seem to matter how long you wait before disconnecting the bottles, the paint does not want to flow back into the bottle without active encouragement.

 

3) Tim's approach of opening the paint valve without air pressure, works in nearly every case - Thank you Tim!    I only had one single instance where that technique didn't work, and that was with a medium thinned (~50%) acrylic black primer that dropped a single droplet out about 10 seconds after disconnecting the bottle, as I was getting my cleaning gear ready between paint change-overs.   Thankfully it hit the tiles in the yard and was easy to clean up.

 

So thanks to everyone for your suggestions and insights!   I'm a very happy airbrusher, once again!

 

Ross.

 

Having noted your location, I can only say 'It's not rocket science' !!

 

Sorry,

John Isherwood.

[Mick Bonwick]

I am pleased for you that the answer has been found. All the experts on RMweb failed you completely, except for Tim. Good result and thanks for persevering and sharing your experiences. You are now an expert!

Edited April 22, 2020 by Mick Bonwick

[RBTKraisee]

7 hours ago, Mick Bonwick said:

I am pleased for you that the answer has been found. All the experts on RMweb failed you completely, except for Tim. Good result and thanks for persevering and sharing your experiences. You are now an expert!

 

While I really appreciate the compliment, I've got a loooong way to go before I'd feel worthy of that word.   Gimme a few years, let me finish my Gresley Triplets and my King's Cross station models successfully, and then I'll be on the right path :)

 

Ross.