Airbrush problem/backfeed?

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Oct 9, 2013
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larger spray tip provides wider spray pattern .
But a larger tip / needle allows spraying higher viscosity coating also .
That's the short answer .
So smaller diameter is for thinner paint and smaller detail. And is it also at a lower PSI the smaller you get?
 

BLT

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The smaller the nozzle...The finer a line can you make.

I think the general consensus is around 0.3 has you cowered. And as with everything else, your experience and the way you work, will influence your preferences.
 

Marktastrophe

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I'm also guessing my packing nut needs a full replace at this point. I'll run one acrylic color through, and rinse/flush it with thinner then cleaner, and by the time my second color is in the AB paint has dried all (not sure on which side) up on the packing nut and only lets out 1/3 or less of the PSI my regulator is reading.

I have another, I just wanted to share that the mini Tamiya cotton swabs don't just fit through the packing nut... but CAN ream said packing nut.
 

urumomo

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Usually it's something dried onto the needle if it's sticking thru the packing
 

Marktastrophe

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Usually it's something dried onto the needle if it's sticking thru the packing
needle has been cleaned at the beginning of use each time. BUT if the packing needle isn't creating a proper seal, I could see how this could cause paint to dry on the needle around that area and compound from there.

I do have a back up needle I can use too, just as a test to make sure there aren't any imperfections or anything on the needle causing issue.
(I can't be expected to keep track of everything that gets dropped... or how many times it gets dropped :p )
 

urumomo

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You pull the needle completely out to clean it , yeah ?
I always do , but occasionally , if it sticks , I'll find that there is still some coating that was missed and needs scrubbing off with an alcohol soaked towel .
It only takes a tiny amount to make it stick .
 

Marktastrophe

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You pull the needle completely out to clean it , yeah ?
I do, at the end of a session, or as needed during long sessions. But I also just pulled it apart after having to crank the PSI way up... and the packing nut looks pretty clean :/

I'll go over the needle again before putting it back together. But just placing the two nuts next to each other, the old one has a visibly larger hole. I just spent my lunch break looking for my calipers to check my eyesight on this, but no luck.

Just slid them over a loose needle, the old one slides right down with almost no resistance, the new one stops at the needle taper with enough resistance to qualify as a possible fix for me.
So I think the issue is what you said urumomo, but being caused constantly by having a blown out packing nut.
The old nut should serve as a nice detail up part on a later build though, so that's something.
 

urumomo

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The packing on mine lasted a few years before I replaced it ,, but , I don't use a breaker-bar to torque everything down . LOL ;)
 

Marktastrophe

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The packing on mine lasted a few years before I replaced it ,, but , I don't use a breaker-bar to torque everything down . LOL ;)
You know... sometimes I can be a walking breaker bar, lol.
This one is about 4 years old now, and it was only earlier this year I accidently put the 87105 below straight through it.
1649269082321.png
 

Little Cutie

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I skimmed over everything you guys just posted here and I keep seeing Vallejo thinner posted time and again. You don't need all this high priced crap. Look - nail polish cleans up real well with acetone or even with xylene. However you wouldn't want to put the latter on plastic because it will mar. Acetone is a solvent based alcohol that flashes off quickly and dissolves in water. It is compatible with most paints as a solvent. But regular rubbing alcohol (isopropyl) will thin paint as well as remove it if it's acrylic. No need to worry about solvency or compatibility. It dissolves and doesn't leave a residue. Neither does acetone. When you rub plastics with it the surface dulls but does not dissolve into a mess. However acetone is expensive and toxic to your nervous system when inhaled on a consistent basis.

Try using 70% or 90% alcohol to thin your paints and practice on scrap. When in doubt - do find out! Try using different needles and paints and different concentrations on garbage models or spare styrene to get the best out of your paints. I use automotive acrylic primer - much more for less that what you pay for name brand garbage in a small bottle that is no better and costs more. Just spray it into a soup can then into a jar for storage so that you can put it an airbrush. Spray cans don't always atomize the best and stop spraying after a while - especially RUST-O-LEUM brand paint!! I too used to think that you needed all brand name junk just because the manufacturer wanted you to buy their stuff so that they could make more money. Trust experience over hype. I had to learn over a long time that there are work around resolutions to many common problems. I only use thinner when I have to spray a light coat that is not meant to be touched ever once assembled. This goes for doll houses and delicate items that you don't want to handle and need a smooth finish. Otherwise I spray it directly from a paint can (spray paint).
 

urumomo

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" Acetone is a solvent based alcohol .. " - No.

" Spray cans don't always atomize the best and stop spraying after a while - especially RUST-O-LEUM brand paint!! " - No

" I only use thinner when I have to spray a light coat that is not meant to be touched ever once assembled. " - WTF

" Trust experience over hype " - OK

Do you even know what is in Vallejo acrylic thinner ?

Decanting aerosol spray cans is far from efficient -- aside from the monetary end , you're boiling off solvents that are a portion of the mix that factor into the performance of the paint ( not talking about the propellant , I'm talking about solvents like butyl acetate etc )
 
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Marktastrophe

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I learned from renovating my first home, you get what you put in our of your tools and equipment. And this is my hobby, creating feeds my being and is a great healing tool. I'm willing to spend money to keep that process as stress free as possible.

When you get away from rattle cans you open yourself up to an huge range of much higher quality paint. SMS is a fine example of cost equating quality.
 

BLT

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I use homemade airbrush cleaner for my Tamiya acrylic paints. One could easily use a homemade thinner as well, but to me the performance of the paint is different when I use Tamyias own stuff. X20A or their lacquer thinner.

For Mr. Finishing surfacer I use their leveling thinner, cus it has a nice leveling effect. For cleaning that I use cellulose thinner, cuz it's somewhat less rough on the seals than acetone.

When using 501 abt oils I use their thinner as well, probably don't need to, but you have to try it for yourself. Using the brand stuff I feel you have the best reference to work from. Either going the DIY rout or cheaper alternatives.

My 2 cents
 

Marktastrophe

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Nov 19, 2021
Messages
297
I use homemade airbrush cleaner for my Tamiya acrylic paints. One could easily use a homemade thinner as well, but to me the performance of the paint is different when I use Tamyias own stuff. X20A or their lacquer thinner.

For Mr. Finishing surfacer I use their leveling thinner, cus it has a nice leveling effect. For cleaning that I use cellulose thinner, cuz it's somewhat less rough on the seals than acetone.

When using 501 abt oils I use their thinner as well, probably don't need to, but you have to try it for yourself. Using the brand stuff I feel you have the best reference to work from. Either going the DIY rout or cheaper alternatives.

My 2 cents
Absolutely! I need to pick up some cellulose thinner to try for cleaning. I've used Model Masters thinner, and rubbing alcohol to thin Tamiya paints, but their lacquer thinner makes their acrylics spray/lay my favorite way so far. (and while the Tamiya Lacquer thinner doesn't make it very shelf stable, it does work for spraying Mr. Hobby Lacquers)

You can mix and match chemicals, but I've found I get the most consistent and quality results (the first time, or close too) by using add-ins designed by the same company that makes the paint... or at least designed to be used with a specific paint. And NOT having to strip things to redo them, as well as NOT having to do more than thinning a paint for pigment prep, is worth it to me. But that is intrinsic value, every one has their own means and assigns their own worth to what they buy/use.

I'll spend a bit more coin to spend more time doing, and less time prepping, fixing, and making work arounds any day.


Follow up, is this the thinner you use, and if so, do you use it with Tamiya Acrylic? Or Something else?
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