painting question.. Help!!

youngwm

Active Member
When painting on a plastic model is it normal to have a like tiny dust bumps or little dusting.. I am painting a model and have primed grey and painting with Tamiya white acrylic paint and seem to get this dusting while airbrushing.. Can this be wiped off?

I am in between coats anyone with knowledge on this please respond!!

Thanks,

MY
 

JPolacchi

Sr Member
Do you mean like a pebbly finish? It might be the paint is slightly drying as it is being airbrushed to the surface or it may be the *filler* in the paint or already on/in the primer.Do you have a water trap on your line?You might also be getting water droplets trapped in your paint as you are airbrshing.Are you thinning and straining your paint?You also need to really mix the paint well (lots of aggitation,mixing/stiring),it needs to be thined correctly and paint should always be strained to keep out clumps and imputrities.You also want to be sure your painting surface is prepped properly. You said you primed the surface and whether you used an enamel or lacqurer primer I don't think that would be a problem for an acrylic to adhearer/bond to, but you should sand your model surface with some mid grade grit (if/when possible).I think at least with 600 wet/dry paper and CLEAN the surface well.This sometimes means a light washing with soap/water and/or a solvent to remove oils,sanding dust/grit and impurities from the model's primed surface and thoroughly allow the surface to dry before painting.Propper paint prep at every stage will ensure a nice, smooth painting surface and finish almost always. I'm just taking a stab at this, perhaps other, more experienced painters&airbrushers will add to this discussion?
 

youngwm

Active Member
Thanks!! I will try and lower the pressure. The area is clean and the paint I did not thin as it seemed to be a milk like consistancey out of the jar and had no clumps. I will remove the paint I have some model stuff to do this and try again tomorrow night.
I always clean the model and it's been sanded I have a home made paint box that I put new paper in for the walls. It's a new compressor Passche d220r compressor with built in filter. I will try and lower the pressure and maybe add a little thinner but the paint Tamiya paint I am currently using seems to be really thin. Now that it is brought to my attention come to think of it.. yea the paint must be drying a little cause I seem to get a micro flake here and there that I notice when the paint starts to hit the model.
At the end I spray straight thinner through and dip the nozzel in thinner and spray against my finger.. I hope that keeps my airbrush clean and in business.

Thanks yet again!

MY
 

JPolacchi

Sr Member
What kind of airbrush do you have? Its always good to dismantle the airbrush and thoroughly soak and clean the parts when finished airbrushing. What you are doing is OK for changing from one color to the other if continously using the airbrush. I would still thin the tamiya even if it does appear to look alright strait from the bottle. 25% I think is the recomended ratio,but I am not sure? With an acrylic extender you might even be able to thin more than 25%. Plus, if thinned you will have an easier time reducing the psi and running your brush on a lower psi.Maybe down to 15 psi or even 12psi?Depends on the paint. I don't know what you are running your compressor at presently, 40 psi is really high.I would'nt go that high unless I was shooting a primer or the entire model was to be covered with the same color ( lots of overspray and you want to apply it on as wet as you can without causing drips&runs I think?). Different paints require different adjustments and acrylics are tough to run on low psi, especially if you are working really close to your work surface because acrylics tend to have high pigment concentration in them. The old lacquers you could really thin down, but the problem with solvent paints is making them *too hot* and that can cause a multitude of problems if over thinned.Urethane paints are an entirely different animal.I was learning from someone a long time ago who worked exclusively with urethanes and you can really thin those down to water consistency without loss of color concentration.He was airbrushing at 7-8 psi and a high psi to him was 10psi I kid you not.However,he was doing very detailed work and the lower you can turn your psi,the closer you can get to your work surface and there's no overspray to speak of to contaminate your other work surfaces.Just FYI.
 

youngwm

Active Member
I have a model master g23 airbrush. After reading the last post I did take a few of the parts apart and have them soaking in thinnner. I also adjusted the compressor down to 17psi (will try) so I am all ready when I get home from work tomorrow. I also noticed that some water came out of the hose when I adjusted the pressure covering the hose with my finger. I have another small filter that I attached to the hose right before the filter that is mounted on by Passache (small metal filter) this was recommended before with my previous set up. I took back a harber Freight model as it was overheating.
I don't have actuall model paint thinner any other household item's I can use? Windex? Paint thinner? This acrylic is not water based but I have some model master paints that are.

Thanks again for the advise, between taking the harbor freight one back the water in the hose problem then it overheated. Now not getting the right finish and always waiting for something to be shipped.. I just want to paint!!!

MY
 

JPolacchi

Sr Member
Sounds like you do need another water trap on your line.If it is an acrylic laquer (and not a water based acrylic) or an acrylic enamel, you can only use the solvents that are designed to reduce them.You cannot use any water based reducers or thinners.It won't do anything but cause a huge mess and an even bigger headache. There are a number of things you can use to reduce water based acrylics. However, almost always you should use the thinners that were made specifically for them.It typically isn't wise to mix and match.You also pretty much want to stick with "ONE KIND OF PAINT" . Its one thing to start with an enamel or laquer primer on your model, but after that you need to decide on using either a water based acrylic like Tamiya,Testors,Model Master,or artist grade acrylic;or an enamel like testors,Model Master, Humbrol etc or some other paint. If you bounce between different paints and brands, due to chemical incompatibility you are possibly setting yourself up for a monstrous disaster.However, basically you are safe as long as you stick with one kind of paint, so if you are using enamels, you can apply between dried/cured coats (but I advise not to custom mix between brands for the above reason mentioned).You can typically thin water based acrylics with distilled water (reccomended) as all the impurities are out of the water.Some folks will do a 50/50 mix of H2o&99% rubbing alcohol and thin their paints a good 25%-30%. There is a fudge factor with most acryics, and you can use the an airbrush medium like Liquitex's with most acrylics I imagine.Advice I have been given was to mix airbrush medium with distilled water 50/50 and then you can greatly reduce your acrylic paint.More than 25% I was told...possibly up to 50%.The airbrush medium has *acrylic* in it, so instead of just thinning with water and over diluting the paint, you are not messing with its chemical or structural properites as much.Sounds complicated, but not really.Windex has been used and many times some folks will add a drop of liquid dish soap to a thinned and mixed bottle paint.The soap reduces the surface tension of the water in the paint.As they say, there is always more than one way to skin a cat but there are some things you do have to keep in mind concerning airbrushing.
 

robn1

Master Member
...I did not thin as it seemed to be a milk like consistancey out of the jar...
I know the general rule is the milk like consistency. But I've always liked the smooth even finish from spray lacquers. I had to decant some lacquer from the cans so I could mix colors, and I was shocked by how thin it was. The black lacquer looked like ink it was so thin. Since then I thin my paints a lot more than I used too and I've gotten much better results from it.
 

JPolacchi

Sr Member
I do not abide the *milk like consistency* of most paints when it comes to thining/reducing.I(as you stated) think it is still to "heavy" and you are forced to run your comprssor/airbrush set up at too high a psi.As mentioned, I think there is still quite a bit of fudge factor when reducing paints and unfortunately the manufacturers don't really tell you the products limits,they mostly all just say 25% as a rule of thumb.You have to experiment which really in the hobby world can be a bit of a pain.Who has time to d@!?*^$! around with expensive hobby paints when all you want to do is start painting and detailing your model.That was always my gripe.
 

youngwm

Active Member
I had a killer head cold last night and all that I accomplished was cleaning my airbrush good with Klean paint thinner. I hope that after work tonight I can strip the paint clean with soap/water. Use rubbing alcohol to make certain all stripping material is off. Let dry good and paint.
Thanks again great advise! One question about paint and thinning I read the posts and think I understand when it comes to using one type of paint that makes sense. The hobby shops that I go to seem to carry Model Master as the main paint. When choosing color sometimes it's in the model master white label and other times the black label. Now my understanding is that the white labled MM paint is water based and the other is not. So when thinnning I can use distilled water if using white label black label I thought rubbing alcohol or a thinner correct?
I did put a small little $10.00 trap on the line before the filter.

Thanks again..

Mike
 

youngwm

Active Member
Sorry when reseaching looks like the black label is for enamel paints and white label is for acrylic.
 

JPolacchi

Sr Member
You can only thin/reduce urethane,enamel and lacquer based paints with *SOLVENTS* made for those paints ONLY.

Acrylics can be thinned with: the designated thinner made for that paint i.e: Tamiya,Testors,Model Master,Pactra,Liquitex,Golden etc,etc,distilled water w/ a very small drop of diswashing soap, rubbing alcohol (but dries fast,sometimes too fast&you will get a pebbly surface finish), a 50/50 ratio of distilled water&alcohol & maybe w/ a small drop of diswahing soap?, windex and/or windshield washing fluid-I think used sparingly-25%?, liquid acrylic/airbrushing medium like from Golden or Liquitex acrylics and/or a 50/50 ratio of airbrush medium&distilled water.

There are some great articles that have been written a dozen times over in Fine Scale Modeler.Maybe go to their web page and see about asking in the tips/techniques and help sections? They usually will get back to you in about a week.
 
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