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Author Topic: help airbrush  (Read 1248 times)

spike

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help airbrush
« on: August 18, 2018, 03:43:48 PM »

when I put paint in my gravity fed airbrush  it just blow it out of the pot and not out of the needle help please
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Mark T

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Re: help airbrush
« Reply #1 on: August 18, 2018, 04:15:44 PM »

Hi Spike it sounds like your air brush is blocked and needs a good strip down and clean.  It probably has a build up of old paint on the needle or the needle housing so the paint is just blowing back
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nemesis

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Re: help airbrush
« Reply #2 on: August 21, 2018, 06:22:52 PM »

If you have been spraying acrylic that could be the cause and you will not be the first to be caught out, nemesis
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Andyn

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Re: help airbrush
« Reply #3 on: August 22, 2018, 02:36:42 AM »

If you have been spraying acrylic that could be the cause and you will not be the first to be caught out, nemesis


What?????????????????????????????????




The fact you've got air coming through your cup means your nozzle is definitely not blocked.

If you've got air coming through your paint cup, it's because you've got an air leak into the cup. Check your nozzle is seated correctly if it's self centering, if it's a screw in check your o-ring is in place and that the nozzle is in properly. Check your nozzle cap is on properly and again if fitted with an o-ring (I've never seen a brush that hasn't got a seal on the nozzle cap) check that's in place.


On another note, what you have described is what is used with cleaner to backflush. Backflushing is a critical tool for cleaning your airbrush, which works by putting cleaner into your cup, loosening the nozzle cap and blowing air though, this bubbles your cleaner through the nozzle tip and back through the cup.
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Brian60

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Re: help airbrush
« Reply #4 on: August 22, 2018, 12:31:37 PM »




On another note, what you have described is what is used with cleaner to backflush. Backflushing is a critical tool for cleaning your airbrush, which works by putting cleaner into your cup, loosening the nozzle cap and blowing air though, this bubbles your cleaner through the nozzle tip and back through the cup.
Its not necessary to loosen the nozzle to induce 'blowback' The easiest way is to as stated put cleaner in the cup. Place a finger tightly over the end of the nozzle and then operate for a few seconds - this is enough to blow air back into the cup. What I do is operate normally, ie spray the cleaner for a couple of seconds, then the finger over nozzle for a few seconds, then as normal for a few seconds. I do this 5 or 6 times and is usually sufficient. This is done immediately after use.
However it seems as though yours has dried paint internally, the only remedy is a strip down and thorough clean of individual parts. I have recently bought an ultrasonic jewelry cleaner to do this for me. They are fairly cheap on ebay around 20 or so, place parts in basket turn on and leave! Cleaner should be whatever is compatible with your paint. For acrylics a airbrush cleaner such as Vallejo's own make or as many on youtube suggest - car windscreen washer fluid. For enamels turpentine substitute or white spirit. However if its really clogged and caked dry internally you will need a stronger solvent similar to acetone, but if you go this route make sure the seals are not rubber but teflon.

TailUK

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Re: help airbrush
« Reply #5 on: August 22, 2018, 06:12:02 PM »

Not a great idea to put the nozzle of anything that passes compressed air against your skin. Use a rag and don't let your finger get in line with the nozzle.  Blowing air into your skin can be fatal.

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unbuiltnautilus

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Re: help airbrush
« Reply #6 on: August 22, 2018, 07:05:28 PM »

Not a great idea to put the nozzle of anything that passes compressed air against your skin. Use a rag and don't let your finger get in line with the nozzle.  Blowing air into your skin can be fatal.


What he says. I got roundly bol***ked once for doing this, never again. Good advice :-))
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Andyn

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Re: help airbrush
« Reply #7 on: August 23, 2018, 02:21:22 AM »

Sticking something over the end of your brush is entirely not advisable as A: what he said B: you'll more than likely end up bending a needle and C: this would only work if you're using a crown cap, dish cap or anything else past your nozzle cap.


The safest and easiest way is to loosen your nozzle cap to backflush, especially seeing as it should never be anything other than finger tight anyway. The only risk here is in a self centering brush with the possibility of it moving, but neither of my self centering Iwata brushes have ever done this.
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unbuiltnautilus

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Re: help airbrush
« Reply #8 on: August 23, 2018, 10:27:31 AM »

I always withdraw the needle using the top lever before doing the above A, and B, not knackered anything yet by using simple precautions.
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Re: help airbrush
« Reply #9 on: August 23, 2018, 11:15:51 AM »

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Brian60

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Re: help airbrush
« Reply #10 on: August 23, 2018, 11:55:07 AM »

100 years ago people used to walk in front of cars waving a red flag because going faster than 5mph could kill you! The air pressure at the tip of an airbrush is 1 to 1.5 bar - 15 to 25psi. The pressure on your face is greater than that if you are out cycling or running!

I didn't mention anything about taking off the cap, that should be  obvious as the needle tip would be exposed and stick in your finger. If the concern is such, then press a piece of rag over the end and press into place with finger instead.

Andyn

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Re: help airbrush
« Reply #11 on: August 23, 2018, 12:14:58 PM »

I didn't mention anything about taking off the cap, that should be  obvious as the needle tip would be exposed and stick in your finger. If the concern is such, then press a piece of rag over the end and press into place with finger instead.


A lot of people run their brushes without the second cap, and a lot of the high end brushes use open caps...
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TailUK

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Re: help airbrush
« Reply #12 on: August 23, 2018, 12:32:11 PM »

The Locomotive Act required a man walking in front of a vehicle not to protect the occupants against excessive speed but to protect other road users against being hit by a quarter of a ton of wood and cast iron at excessive speeds.
 The problem with compressed air is  that it doesn't just come at 1-1.5 bar.  The highest pressure I've ever seen operating was 60,000 psi but I've actually used spray equipment up to 60 psi (4 bar)
It's like one of those goofy thriller movies when the assassin kills someone with a syringe full of air.  Now the amount of air in a syringe can kill you if it gets in a major blood vessel.  Injected into muscle it would just be painful, akin to the bends.  The danger lies in the volume of air.  Even at 1.5 bar a air brush can pass a cubic foot of air pretty quickly and should it enter the skin through a cut or lesion would be extremely  painful. At greater pressures it can go through skin easily as in a Bio Innoculater (spray syringe). So there's a good chance that holding your finger over a spray nozzle may not hurt you but why risk it when it's as easy to do it another way.
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Brian60

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Re: help airbrush
« Reply #13 on: August 23, 2018, 12:55:05 PM »


A lot of people run their brushes without the second cap, and a lot of the high end brushes use open caps...
Yes I do both. With the cap off you can spray a much finer line, almost like handwriting a letter if the brush quality is good enough. I also have a n Iwata brush that has a split/open end cap, the reason for this is so that needles can be  quickly and easily cleaned off without the need to remove the cap. But that is getting into the more technical side than just removing dried paint from within the body which is what the article was originally alluding to.

Brian60

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Re: help airbrush
« Reply #14 on: August 23, 2018, 01:00:44 PM »

The Locomotive Act required a man walking in front of a vehicle not to protect the occupants against excessive speed but to protect other road users against being hit by a quarter of a ton of wood and cast iron at excessive speeds.
 The problem with compressed air is  that it doesn't just come at 1-1.5 bar.  The highest pressure I've ever seen operating was 60,000 psi but I've actually used spray equipment up to 60 psi (4 bar)
It's like one of those goofy thriller movies when the assassin kills someone with a syringe full of air.  Now the amount of air in a syringe can kill you if it gets in a major blood vessel.  Injected into muscle it would just be painful, akin to the bends.  The danger lies in the volume of air.  Even at 1.5 bar a air brush can pass a cubic foot of air pretty quickly and should it enter the skin through a cut or lesion would be extremely  painful. At greater pressures it can go through skin easily as in a Bio Innoculater (spray syringe). So there's a good chance that holding your finger over a spray nozzle may not hurt you but why risk it when it's as easy to do it another way.
The point I was making was the fact we can be too safety conscious. Rather like in the glue section whenever there is a mention of using MEK as a bonding agent- its sold as a plastic glue in model shops no problem, but you mention buying it in litre bottles on ebay because its way cheaper and everyone starts on about the safety aspects of it, which seem to be completely ignored when you buy a 70ml bottle from the model shop.

TailUK

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Re: help airbrush
« Reply #15 on: August 23, 2018, 01:37:22 PM »

I don't think we can be too careful about safety but I agree it needs to be tempered with a little common sense (ever notice that despite being "common" sense there's precious little of it about)  The law is full of weird loopholes which are the bane of my working life.  Working as a Technical Instructor means I have to keep aware of the regulations no matter how daft some of them seem to be. For example, we don't allow our students to use our circular saws (the insurance company would have kittens) but a student could buy one at Homebase and with no experience at all, use it at home. 
       As for solvents don't get me started.  When I first got into this business MEK and Dichloromethane weren't as easily available, so to glue acrylic we used Chloroform.  You could buy it the chemist as long as you signed the poisons book.
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