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AFV Painting & Weathering
Answers to questions about the right paint scheme or tips for the right effect.
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Airbrush Paint dried to powdery coating
StanNC
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North Carolina, United States
Joined: November 27, 2012
KitMaker: 26 posts
Armorama: 21 posts
Posted: Monday, August 13, 2018 - 07:17 AM UTC
Any one with ideas as to a cause or cure for airbrushed paint that will rub off with mild handling. Never experienced this type of problem before.
I am trying to paint a Tamiya M-10 with Model Master enamel Olive Drab ANA 613 # 2050. I am using an Azetec airbrush with red nozzle. Paint was diluted with lacquer thinner to the consistency of 2% milk. Model parts were pre-washed with 409 cleaner before and after assembly rinsed with tap water and air dried for several days. Air pressure was 20 PSI. Temperature was 80 deg F; relative humidity was approximately 50%. No primer was applied, paint was sprayed in several thin coats. Sprayed at a distance of 2 - 3 inches from surface.
The result was wet looking after spraying, but upon drying the next day it was a dusty coating that came off with gently handling.
Any help and advice would be greatly appreciated.
Second question, any suggestions as to how I can remove this paint coat or what I can do to repaint? The parts involved were the gun and bogies so sanding each is sort of out of the question.
Thanks for any and all help.
petbat
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Queensland, Australia
Joined: August 06, 2005
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Posted: Monday, August 13, 2018 - 08:20 AM UTC
Likely cause was paint drying before it reached the model or paint pigments were not thoroughly mixed. I presume you did not add any matting base?


There are several ways to strip paint, such as a Caustic Soda bath, oven cleaner (not a natural one), automotive Brake cleaner, etc.


I have used the first 2. An old icecream tub is ideal to store the model while giving the product time to work. Do not leave it too long and have an old bristle brush like a toothbrush handy to help remove the softened paint in the crevices. Just remember to wash the model throughly later and let dry.
GulfWarrior
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ARMORAMA
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Posted: Monday, August 13, 2018 - 08:34 AM UTC
I agree with what my esteemed colleague from down under says. I actually had this happen to me using Testor’s MM Acryl on the M1117 Guardian I’m currently working on. Fortunately it was on the underside. A little Windex on a toothbrush and I was running and gunning again in no time.
nsjohn
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Scotland, United Kingdom
Joined: July 26, 2018
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Posted: Monday, August 13, 2018 - 10:16 AM UTC
Be very careful with oven cleaner. One of my friends ended up in hospital through not using gloves. Revell do a paint remover which I used to strip a Ferdinand when the spray varnish reacted with the Tamiya Acrylics and gave a corrugated effect. I also understand that certain types of Dettol will effectively strip paint, but haven't tried that (yet)
Vicious
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Queensland, Australia
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Posted: Monday, August 13, 2018 - 10:44 AM UTC
It could also be the fact that the Laquer thinner dries too quickly and does not allow the paint time to self-leveling.
StanNC
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North Carolina, United States
Joined: November 27, 2012
KitMaker: 26 posts
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Posted: Tuesday, August 14, 2018 - 08:19 AM UTC
Thanks to all for your thoughts and suggestions.
I have been thinking as others have suggested that the paint was drying prior to hitting the surface. First time this has happened to me.
As follow-up questions:
What concentration of caustic soda would you suggest for stripping? I believe oven cleaner is caustic in a gel substance (possibly cellulose type formulation).
Has anyone had this powdery coating experience and tried a good toothbrush scrub with say 409 cleaner, thoroughly wash, dry and then tried to re-coat without stripping?
Appreciate all further thoughts on this matter.
petbat
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Queensland, Australia
Joined: August 06, 2005
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Posted: Tuesday, August 14, 2018 - 12:09 PM UTC
Sorry to hear about your friend Norman, As with any products that will strip paint, you must wear gloves and protection for your eyes to keep the stuff off your skin. The product labels are fairly specific on that.

Stan. Here in OZ, oven cleaner can be acquired in an aerosol and is more of a foam and you spray it over the model - using gloves to turn it around, etc, so the spray coats it all.

Caustic soda can be acquired as granuals or chunks, depending on the brand. I suggest you read the label for uses and how to dilute it, as each is different. You do not need a lot. It is a chemical that reacts with water and will get warm to hot.... don't be shocked. Make a 'mild' solution and leave it overnight.

You can also get aerosol paint stripper from hardware stores meant to strip back household paint, (from cast metal furniture, etc) but may work with model enamels.

I have not heard of Windex or Dettol working on enamel paints - maybe the guys did not pick up on the paint you used. So many people use acrylics these days, it is easy to assume.

..... and yes, I have had it happen, which is how I deduced your problem. Consider spraying lighter coats with as low pressure you can, and spray closer to the model. The old Aztec is not a forgiving airbrush either... that from experience too.
nsjohn
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Posted: Tuesday, August 14, 2018 - 01:07 PM UTC
And he was using it to clean an Oven. Dettol does seem to work on both enamel and acrylic paint according to a number of You Tube videos.
petbat
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Queensland, Australia
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Posted: Tuesday, August 14, 2018 - 03:05 PM UTC

Quoted Text

And he was using it to clean an Oven.


Ouch. Some people are more susceptible to chemical burns than others, but a burn is still a burn.

I pay a guy to come out and do mine professionally. He cleans it better than I could ever do it with the stuff we can buy. You would think he was ready to disarm an IED the way he covers up though.

Thanks for the tip on Dettol. You certainly can teach and old dog new tricks...
smorko
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Serbia & Montenegro
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Posted: Tuesday, August 14, 2018 - 06:59 PM UTC
Have you used lacquer thinners on MM enamels before? Lacquer thinner will dissolve enamel paint but also the binder so nothing is there to stick or give body to the paint. Good for cleaning brushes, not for thinning. A good thinner for airbrushing doesn't affect the binder qualities. That is why most companies have thinners and cleaners as separate items.
Scarred
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Washington, United States
Joined: March 11, 2016
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Posted: Tuesday, August 14, 2018 - 07:18 PM UTC
Lacquer thinner evaporates way to fast and paint won't properly stick, lacquer thinner isn't for enamels. I've tried it in the past without good results. Get some decent enamel thinner or the Testors brand thinners. I've learned the hard way that all manufacturers are slightly different and that the easiest way to avoid issues it to go with the thinner made by the manufacturer. It may cost a buck or two more but here you are having to strip a paint job so your are out the money for the paint, the lacquer thinner, the over cleaner or what ever you are going to use to strip the paint. Also before sticking your model in a caustic agent, take an unused part or a piece of sprue from the kit and test the cleaner on it first to make sure it's not going to damage to plastic.
tanknick22
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Posted: Tuesday, August 14, 2018 - 10:10 PM UTC

Quoted Text

Lacquer thinner evaporates way to fast and paint won't properly stick, lacquer thinner isn't for enamels. I've tried it in the past without good results. Get some decent enamel thinner or the Testors brand thinners. I've learned the hard way that all manufacturers are slightly different and that the easiest way to avoid issues it to go with the thinner made by the manufacturer. It may cost a buck or two more but here you are having to strip a paint job so your are out the money for the paint, the lacquer thinner, the over cleaner or what ever you are going to use to strip the paint. Also before sticking your model in a caustic agent, take an unused part or a piece of sprue from the kit and test the cleaner on it first to make sure it's not going to damage to plastic.


I had that happen with model master enamel paints thinned with mineral sprits but it was the paint or thinner that caused the paint to dry as it left the airbrush it was the temp since i live in a apartment i have to airbrush out side
it was hot out that day and another cause was i was to far away from the subject i was airbraushing

Scarred
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Washington, United States
Joined: March 11, 2016
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Posted: Tuesday, August 14, 2018 - 11:25 PM UTC

Quoted Text


Quoted Text

Lacquer thinner evaporates way to fast and paint won't properly stick, lacquer thinner isn't for enamels. I've tried it in the past without good results. Get some decent enamel thinner or the Testors brand thinners. I've learned the hard way that all manufacturers are slightly different and that the easiest way to avoid issues it to go with the thinner made by the manufacturer. It may cost a buck or two more but here you are having to strip a paint job so your are out the money for the paint, the lacquer thinner, the over cleaner or what ever you are going to use to strip the paint. Also before sticking your model in a caustic agent, take an unused part or a piece of sprue from the kit and test the cleaner on it first to make sure it's not going to damage to plastic.


I had that happen with model master enamel paints thinned with mineral sprits but it was the paint or thinner that caused the paint to dry as it left the airbrush it was the temp since i live in a apartment i have to airbrush out side
it was hot out that day and another cause was i was to far away from the subject i was airbraushing



Back in the old days Testors (and Pactra and Humbrol) could be thinned with just about any thinner. Early Model Masters was like that too. But when I was in Europe in the late 80's I found the thinner I got over there didn't work too well with MM. I went to a hobby shop and got a tin of actual Testors thinner and no problems with MM. Got back stateside and got some thinners at the local hardware store and again they didn't play well with MM so I got some of their thinner again and yup, no problems. After that for thinning purposes I started sticking with the thinners, levelers and reducers produced for the line of paint I'm using. I only use generic thinners for cleaning now.
TopSmith
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Posted: Thursday, August 23, 2018 - 12:20 PM UTC
Don't use lacquer thinner to strip acrylic paint on your models. It melts the plastic. I tried it on a rear storage box on a Panther. It partly stripped the paint and partly melted the surface detail. However, 90% alcohol worked very well in about 30-45 minutes using a soft toothbrush.
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