MM Black thinning trouble.

Wulf wrote:

OK, I think I know what you are talking about now. Sounds like the paint is drying before it hits the surface. In turn, you are getting a 'gritty' texture to the paint. Is this the case? If so, I would switch your thinner to 70% isopropyl . 90% alcohol will "dehydrate" the suspension solution in the paint and causes it to dry out too quick. This will result in a clogged airbrush tip and a rough paint job. Also, you may want to reduce your operating psi to 10-12 psi. Liquitex brand makes a product called slo-dri. You can get it at any art store or Hobby Lobby. Adding some to the paint will increase the dry time and eliminate premature drying and avoid a rough finish.  A high grit sand paper or pad (8000 grit) will smooth and polish any rough surface. Just make sure the paint is fully dry first. Hope this helps.... Andy

Thanks

 I will try the 70%  isopropyl and distilled watter and see how that works. I also didn't realize that 90+% isopropyl will cause quicker dry times and does explain unrelated problems i've been having with my AB.

 I have also switched to nearly 100% hand brushing due to a lot of traveling in which I still continue to work on models. The problems I mentioned above did not involve a AB, I noticed the problem while string the paint with the 99% isopropyl in a small plastic paint tray. 

 Also on a slightly unrelated note, i find tamiya acrylics horrible for hand brushing even when i apply a unthinned coat that I let dry for 3 days, with a primed surface and no finger grease involved. It is just so damn easy to strip the previous layer of paint with a brush that I have to apply a clear coat in between (which works well). It also drys to the touch so fast I have no rush the painting to avoid getting little balls of semi dried paint after a brush stroke. MM acrylics have no such problems and works very similar to humbrol enamels but no nasty chemical fumes. For AB i find tamiya to work well. 

OK, I think I know what you are talking about now. Sounds like the paint is drying before it hits the surface. In turn, you are getting a 'gritty' texture to the paint. Is this the case? If so, I would switch your thinner to 70% isopropyl or distilled water instead. 90% alcohol will "dehydrate" the suspension solution in the paint and causes it to dry out too quick. This will result in a clogged airbrush tip and a rough paint job. Also, you may want to reduce your operating psi to 10-12 psi.

Liquitex brand makes a product called slo-dri. You can get it at any art store or Hobby Lobby. Adding some to the paint will increase the dry time and eliminate premature drying and avoid a rough finish. 

A high grit sand paper or pad (8000 grit) will smooth and polish any rough surface. Just make sure the paint is fully dry first.

Hope this helps....

Andy 

Not really qualified to answer your question but I hate to see someone left hanging, I know the feeling...

I've only used MM Acryl a few times. Bought several bottles of it a few months ago and ran a little through the airbrush before getting sidetracked. I got the same reaction as you with flat black, flat and gloss white. The other colors seemed to thin normally but I did get a lot of tip dry. I switched from 91% alcohol to distilled water and didn't have any problems or nearly as much tip dry. Also got a bottle of MM Acryl thinner but haven't had a chance to try it yet. I have no idea why the different colors reacted the way they did.

Tony

I'm at a loss. I use MM flat black all the time and never had this problem. I use the 70% isopropyl instead of the 90% though. I thin mine about 40-50% thinner. I would make sure the paint is well stirred. Other than that, I'm not sure. Sorry......

Andy 

Ah yes, forgot to mention that I don't have access to MM acrylic thinner.