Acrylic thinning question: Methanol or Ethanol?

[rallymodeller]

I'm about to take the plunge -- I'm getting rid of my enamel paints. Goodbye little tins of Humbrol!

But I'm not really familiar with the ins and outs of acrylic paint. I've been reading all the threads I could about acrylic paint to get my head around a new (for me) finishing medium.

So here's my question -- there will probably be more to come.

I can get methyl hydrate stupid cheap at my auto parts store. It's basically straight methanol for $2/liter (it's a diesel conditioner and gas line antifreeze). Would this be good for most acrylic thinning and/or airbrush cleaning duties?

[Kylwell]

er... Terror! Git yer butt over here we have a chemistry question!

I know we used windshield washer fluid to clean a/b @ the M&Ts.

[Lt. Z0mBe]

I dunno about straight methanol for thinning. However, I have used windshield washer fluid for thinning some brands of hobby acrylic paint when trying to get it down to that "milk like" consitstency prior to straining. It is about 75-percent water and 25-perecent methanol.

The best ""universal" solvent, if you will, seems to be Windex with Ammonia, with 90-percent isopropyl and the windshield washer fluid being my backups. Windex with Ammonia has Ammonia (duh!), water and ethylene glycol. The ammonia has an effect on the acrylic (latex) bonders: it makes them soft and "snotlike" when emulsified. The ethylene glycol helps with the emulsification in that it is roughly in the middle of alcohol molecule sizes and is not too reactive, so it is not likely to make acrylic polymers "clabber" and instantly crosslink, though it does occasionally happen. It intersperses between the little bundles of binder and ammonia and water and helps maintain the emulsion. Addiitionally, the ethylene glycol doesn't evaporate as quickly as isopropyl.

Isopropyl is used when the test with Windex with ammonia fails due to clabbering. The disadvantage of thinning with isopropyl is it can dry as sprayed, so you have to watch your pressure.

Finally, if all else fails, go to the windshield washer fluid. It seems to work when all else fails. The isopropyl alcohol seems to work more often, for me, that the windshield washer fluid. This makes sense as researching these things indicates few of the manufacturers use methanol-friendly formulations; they either bead up or run. So, through process of elimination, go through the two most probable ones before hitting the isopropyl.

I hope this helps.

Kenny

[eeun]

I started out thinning my Tamiya with methyl hydrate. No problems at all.
Switched over to isopropyl only because I ran out of the former. One works as well as the other.

Beware that some acrylics (Createx, and some but not all "craft" paints) will turn into a horrible gelatinous goop if you try to thin them with isopropyl or methyl hydrate.

Windex works well for every acrylic I have, but I prefer the alcohols as they go on less wet and will dry much faster.

Only other tip I have is adding a little Future to alcohol-thinned Tamiya helps prevent the paint from frosting if you're applying a very thin mix.

[TER-OR]

Most acrylic thinners tend to be somewhat larger alcohols, Jeremy. Butanol, 2-butanol, propanol etc. I'd avoid methanol as it can be corrosive and damaging to some rubbers, too.

[rallymodeller]

Gave methanol a try today with PollyScale.

Red -- fantastic. Worked very well.

Green -- not so much. Got a little gooping. Gonna try washer fluid tomorrow and see haw that goes. If all else fails I can hit the art supply stores.

[Kylwell]

See! I knew Ter would save the day.