Airbrush chewing Gum

[Steve Brodie]

Any body ever experienced, what i can only decribe as, chewingum in their airbrush. Smaller than a pea sticky gunge stuff that turns to paste when between your fingers ?

[papa 695]

Hi Steve first of all what type of airbrush have you got ? Some of the cheaper types have rubber seals and if you put neat thinners through it it can melt it and as the needle pushes through it forms the chewing gum type mess your talking about.


Second. What was you doing just before you found the chewing gum type mess ?


You can get the same type of mess if you use thinners in some types of acrylic paints

[Guest]

Sorry Ian, but I've used cheap airbrushes with cellulose thinners neat & have never melted a rubber seal.


In fact, there aren't any to melt in most generic Chinese airbrushes - the only rubber o-rings are in the crown nozzle cap & air hose fitting - neither of which come into contact with paint or thinners.


But you're right about mixing acrylic brands - Tamiya thinners & Vallejo paints will cause a semi-solid mass.

[Steve Brodie]

Sorry Ian, but I've used cheap airbrushes with cellulose thinners neat & have never melted a rubber seal.
In fact, there aren't any to melt in most generic Chinese airbrushes - the only rubber o-rings are in the crown nozzle cap & air hose fitting - neither of which come into contact with paint or thinners.


But you're right about mixing acrylic brands - Tamiya thinners & Vallejo paints will cause a semi-solid mass.

And that must be the answer - Vallejo paints and (couldn't find my Vallejo thinner in my airbrush kit anywhere) Tamiya Thinners. Only used them as I had tried to thin some paint with the Vallejo airbrush cleaner, but after that didn't work, tried the 'bad combination' - oh well lesson learned - airbrush nice and clean inside now, just need to give it a test.


Took ages to get it all out, like picking out cockles from their shells, gunge didn't want to let go at all.


Big lesson learned - thanks all. BTW Iwata NEO

[papa 695]

Sorry Ian, but I've used cheap airbrushes with cellulose thinners neat & have never melted a rubber seal.
In fact, there aren't any to melt in most generic Chinese airbrushes - the only rubber o-rings are in the crown nozzle cap & air hose fitting - neither of which come into contact with paint or thinners.


But you're right about mixing acrylic brands - Tamiya thinners & Vallejo paints will cause a semi-solid mass.

I'll give you that one Patrick it could just be an Urban Legend

[Guest]

I'll give you that one Patrick it could just be an Urban Legend

A bit like the old one our mum's told us about leaving a tooth in a glass of Coke overnight & how it would have dissolved by the morning!


That put me off fizzy drinks!

[stona]

It's not entirely an urban myth. Some airbrushes do have O rings or seals which are not resistant to some 'hot' solvents. The myth is that they dissolve them when in fact they tend to make them dry and inflexible, sometimes cracked, causing them not to do what they are supposed to.


This doesn't just mean parts like the needle packing which will always come into contact with any solvent used but any seals or rings anywhere else (like the nozzle cap) which might be exposed unless you are very careful.


Cheers


Steve

[Guest]

It's not entirely an urban myth. Some airbrushes do have O rings or seals which are not resistant to some 'hot' solvents. The myth is that they dissolve them when in fact they tend to make them dry and inflexible, sometimes cracked, causing them not to do what they are supposed to.
This doesn't just mean parts like the needle packing which will always come into contact with any solvent used but any seals or rings anywhere else (like the nozzle cap) which might be exposed unless you are very careful.


Cheers


Steve

The myth.


Is it a fact Steve that if you used cellulose to clean your airbrush that certain inferior rings


(Chinese) would , if not destroy the rings, make them all sticky and then unreliable


when they had "cured". Probably overtime.


Laurie

[Guest]

Well my ring certainly wasn't inferior! :P


Although as I've previously said, where are these o-rings that can be damaged by cellulose thinners?


The AB that I used to have was a BD 30 ,a very common Chinese one that's supplied with most compressor kits.


Where the paint or thinner goes are no seals, no needle packing.

[stona]

There must be some kind of needle packing at the back where the needle passes into the paint cup on a gravity feed brush. Not sure how that works for a siphon feed as I've never owned nor used one, though I'd be surprised if there wasn't a gasket or two in the cup/paint feed train


Laurie it's entirely possible that the 'rubber' of the seals is rendered gooey before becoming brittle. I've seen airbrushes with brittle seals, not always in the body of the brush. There are often O rings in the air valve assembly and in the nozzle/nozzle cap assembly as well.


Cheers


Steve

[Guest]

There must be some kind of needle packing at the back where the needle passes into the paint cup on a gravity feed brush

Actually that is true on an Iwata. Darn nuisance they are as well. For me they are


always getting stuck to the needle however I clean. Even back up the airbrush


cleaner into the body of the brush. Not that i use anything other than water


soluble based products.


In the H & S brushes there isn't a packing and not had problems.


Laurie

[stona]

In the H & S brushes there isn't a packing and not had problems.


Laurie

Yes there is. On the Infinity series it's part number 123450. Part 123471 is the retaining screw for what H+S call the 'needle seal'. There has to be something to prevent the medium flowing back past the needle into the back of the airbrush.


Incidentally I've had one of my Iwata brushes for over ten years, often use relatively hot solvents and have never touched the needle packing. I'm not sure what you were doing to yours


Cheers


Steve


Edit: more than fifteen years.

[Guest]

Yes there is. On the Infinity series it's part number 123450. Part 123471 is the retaining screw for what H+S call the 'needle seal'. There has to be something to prevent the medium flowing back past the needle into the back of the airbrush.
Incidentally I've had one of my Iwata brushes for over ten years, often use relatively hot solvents and have never touched the needle packing. I'm not sure what you were doing to yours


Cheers Steve Edit: more than fifteen years.

Ouch you are right Steve. You devil you looked it up as I know you have Iwata brushes.


That really is cheating


Got two H & S brushes and did not know that even though I have two sets of seals with


the needle seals in amongst them. Strange thing not had any problems with these seals


so never had to replace. That goes for all my airbrushes never changed a seal yet in 10


years h & S and Iwata.


But I do on the Iwata have needle stuck up on the packing. Assume that my needle gets


stuck as I use acrylic and you use enamel. Actually looking at the H & S it looks a more


rugged affair as opposed to the Iwata which looks very flimsy indeed.


Laurie

[Guest]

Being a nosy devil I thought I would see what happens mixing Vallejo and Tamiya X-20A thinner.


Airbrushed it and it did with out any difference to pure Vallejo. In fact it airbrushed very well.


Also says on the Tamiya bottle water soluble.


Also did a search and found quite a few have used the same above concoction with sucess.


So where your chewing gum came from Steve is perhaps another source than Vallejo


and Tamiya Thinner.


Laurie

[stona]

Hi Laurie, it's just that I knew there had to be something there for the brush to work. I looked up the part numbers for ease of reference. There are so many little bits and pieces it's easy to get them confused, particularly when typing descriptions over t'internet!


Cheers


Steve