Airbrush problems

Runway

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Jan 3, 2021
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I ordered the AK thinner to go with the paint. One more Q. With this AK paint. Wil it mess up a acrylic primer like Vallejo?
 

urumomo

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No .
It's all acrylic resin and the solvent quantity is low enough that it's not an issue .
 

Runway

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I want to TY for all your help this weekend. I hope i can go back and use your replies as notes in the future?
 

urumomo

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Glad I can be of some help .

As far as the AK or other lacquer acrylic paints affecting the acrylic primer ,
If you were to do a lot of brush painting of it atop the Vallejo primer you might run into some issues since the volume of paint and therefore solvent will be higher than airbrushing and you'd have the added impact of the mechanical element of the brushing .
It might begin to soften the primer enough to debond it .

I prefer using alkyd primers ( enamel ) or the lacquer acrylic primers like Tamiya's rattle-can ones or those sold as automotive primers .
They bond much much better to plastic .
The Rustoleum alkyd primers made for plastics work very well ( The ones labeled " 2X " ) --- their vehicle contains acetone and butyl acetate , the same components of Tamiya's Extra Thin plastic cement , so they bond extremely well to polystyrene .
But , you need to give them the full 5-7 days to cure prior to overtopping them .
 

Peppylepugh

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If I may add 2¢ of opinion.
Momo, has you on the right track, you can rest assured.
Are you getting buildup on the nozzle tip? That’s something that will give you a rough surface, when it’s added back into the spray stream. Something to check every couple of seconds when spraying.
I am a very big proponent of straining paint before spraying it. Adds an extra step or two, but eliminates this variable when your about to throw everything out the window. Get all the gremblys out of the paint, so you can be reasonably assured of smooth flow through the brush. Got this tip from the legendary Bill Whitley of Broome County IPMS fame and have stuck to it for decades.
Usually, you can get away with erroring to the side of ‘too thin’ but you have to turn the pressure down and move in closer.
I’ll be interested in the end result and will follow along. May be a pain in your backside, but we are also learning in the the meantime.
 

urumomo

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Dry tip will still occur with the paint strained or not .
Good advice to check the tip for build up while spraying , although I didn't consider it might be the case with such a high percentage of the mix being thinner .

I never mix the paint and thinner in the AB paint cup .
I use a tiny container -- usually the bottom portion of a small pill container , aspirin etc - and then pour the mix into the paint cup.
Ensures a uniform mixture and a chance to remove any obvious contaminants , or add more paint or thinner to get the proper viscosity prior to committing it to the AB .
 

Peppylepugh

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Top of the morning.
Yes, the curse of dry tip.
Just throwing it out there, seeing what sticks.
With my recent change over to Tamiya, I’ve been
pre-mixing in old Testor bottles from the stash. Found a vendor who sells just the caps. At this rate, his kids are secured a college education.
The variables in the thickness from color to color was throwing off some of the color recipes to where I was tossing more than I liked.
Tamiya Black is an extremely intense color. Too thick of a blend and your RLM 02 just turned to primer grey and I have enough of that already, thank you.
So, I figured if I could start with fairly consistent viscosities across the board I’d be that much further ahead and not dumping paint out.
But, yeah, one of Bill Whitley’s tenants, was not to mix in the brush, for your reasoning exactly.
Know, what you are putting in there, before you put it in there.
I know there is a joke in there, but can’t quite…
 

Runway

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Jan 3, 2021
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84
Thank you both. But after a long weekend or interrogating Momo. I figured out a lot of problems that I made being a first-time airbrusher. When using the Valero non thinning primer yes the gun was not clean thoroughly after each application. That was mistake 1#. Not matching the paint with the thinner was mistake number two. Having the gun too far away from the model and air pressure too high mistake number 3. Now some guys mix in cup and some do not. I am fighting with both ideas becaues mixing in a separate container looks like I'm wasting paint as i pore it in to cup. So the first coats of color went on great. And i thought i applied enough paint for the model. But by moving the model i noticed a small Nick which remove the paint from the model. Witch tells me i need more coats? Paint did not chip off. It's like a scrach. So back to the paint booth?
 

urumomo

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I'm not sure I understand the issue with the paint being scratched off .
Keep in mind that acrylic needs time beyond being dry to the touch to fully cure into a strong layer .
The polymer chains need to crosslink which takes time - higher temps speed this up .
Think of it like touching Velcro hook & loops together . If you touch them together loosely they stick but the joint is weak .
That is the initial dry to the touch acrylic .
Push them together with more and more pressure -- the increased time / temp -- the joint becomes very strong due to the full entanglement of the hooks and loops . The full crosslinking of the polymer chains .
In short , " green " coatings are weak and easily damaged .

Also , 3 coats of primer shouldn't be necessary .

I know what you mean about trying to avoid wasting paint when mixing in a separate container and then pouring the mix into the AB paint cup .
That's why I use the smallest mixing container I can .
I cut the very bottom off of aspirin or other pill bottles . The bottom 5 mm sometimes .

I use that tiny spoon ( it's for clay sculpting ) to ladle out paint from containers like the AK Real Colors that don't have the dropper top .
It results in less waste , and much easier to clean , over using a pipette since there is far less surface area involved :

Wk92OE7.jpg


I use them for all kinds of paint tasks .
 

urumomo

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Mar 18, 2013
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3,055
One ?
Two ?
Three ?
The fewest necessary to get the color depth you're after .
This is the problem with troubleshooting remotely like this . There are so many factors regarding paint application .
The primary concern is destroying finer details with multiple coats of paint . Or paint runs or ponding with a single heavy application .
 

Runway

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Jan 3, 2021
Messages
84
The instructions say 70% light gray. 30% gray but looks darker then the pic on the instructions. But more looks like the Studio model. But the applications of the paint look great. Wish the primer came out that well. But that is water under the bridge. No running no ponding.
 

Runway

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Look.
 

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Peppylepugh

Active Member
Joined
Mar 27, 2012
Messages
195
I'm not sure I understand the issue with the paint being scratched off .
Keep in mind that acrylic needs time beyond being dry to the touch to fully cure into a strong layer .
The polymer chains need to crosslink which takes time - higher temps speed this up .
Think of it like touching Velcro hook & loops together . If you touch them together loosely they stick but the joint is weak .
That is the initial dry to the touch acrylic .
Push them together with more and more pressure -- the increased time / temp -- the joint becomes very strong due to the full entanglement of the hooks and loops . The full crosslinking of the polymer chains .
In short , " green " coatings are weak and easily damaged .

Also , 3 coats of primer shouldn't be necessary .

I know what you mean about trying to avoid wasting paint when mixing in a separate container and then pouring the mix into the AB paint cup .
That's why I use the smallest mixing container I can .
I cut the very bottom off of aspirin or other pill bottles . The bottom 5 mm sometimes .

I use that tiny spoon ( it's for clay sculpting ) to ladle out paint from containers like the AK Real Colors that don't have the dropper top .
It results in less waste , and much easier to clean , over using a pipette since there is far less surface area involved :

Wk92OE7.jpg


I use them for all kinds of paint tasks .
Excellent idea for repurpose around the house.
Easily rinsed out and you are good to go.
Don’t have any close to hand, but I use cheap stainless steel cocktail sauce cups that I was getting at about .75 cents at WallyWorld ten years ago.
Anything, anytime, with a quick swish of Windex with Ammonia D and it’s out the door and ‘round the corner.
Yes, very good.
 

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