I have used pink Windex. It does not have ammonia and works great as both a cleaner and a thinner.
Windex is supposed to be window cleaner, but when I want clean windows, vinegar and water works better and is cheaper.
I can’t imagine why anyone would use it to thin paint or, for that matter, use alcohol to thin acrylic paint.
When I first attempted to airbrush acrylic paint, I followed the advice found here and on other model railroading forums and tried isopropol alcohol. Many posters also advised that the pressure should be between 35-50psi. Well, that almost cured me of any further ventures using acrylics in my airbrush. However, needing to paint some rolling stock and unable to find Floquil locally, I took a chance and checked out the Pollyscale website.
What a surprise to learn that the manufacturer recommended the use of distilled water as a thinner and that air pressure should be between 15-20psi.[:O] I was even more surprised to find that it not only worked beautifully, but in that entire painting session, 48 undecorated Accurail boxcars, the airbrush did not clog even once.
That compared to the high pressure attempts with alcohol, where not even one car could be painted without clogging.
By all means, feel free to use whatever you wish, and be sure to let us know how it comes out. [swg]
Wayne
Sadly, that info is becoming obsolete as the remaining stocks of Pollyscale get used up (or go bad).
Testor’s “successor” paint line, Model Master acrylic, makes no mention of distilled water, only special Testor’s thinners on their FAQ*. Recommended pressure range does remain at 18-20psi., though.
And to clear things up, Model Master Acryl does NOT need thinning for airbrushing, except when it does. [:P]
*No sure why they used clip-art of a woman grinning maniacally while holding pain brushes in their page header. Art directors are weird.
Yeah, that’s one of the reasons why they’ll no longer be getting any business from me: selling pre-diluted paint (less paint with more thinner) which is absolutely useless for brush painting does no one but the manufacturer any favour.
On my next trip to the States, I’ll be heading to Northumberland PA to pick-up some Scalecoat - between my needs and those of a friend, probably three or four hundred dollars worth.
Wayne
Which Scalecoat are you speaking of Wayne ,Regular or Scalecoat II ?
I’ve only used the regular (original) version, but I think that my friend is considering Scalecoat II, as he does a fair amount of brushwork.
I’ve not had any problems airbrushing the solvent-based stuff on plastics, but brush-painting results may prove different. I still have a fairly substantial collection of old Floquil and original Pollyscale. The Floquil will likely be used-up mostly on structures due to the colours I have left, while the Pollyscale is suitable for freight cars and figures, and some structure painting, too.
Wayne
Or you could spend 9 months “scratchbuilding” a baby, and THEN get some baby food. 
I think the baby joke was made several posts up, so I don’t know why Owen attempted it again. Besides, a number of our forum members are in their 80s and 90s, so a new baby may not be in the cards for them - perhaps a grandkid or two.
Anyway, the first attempt I made last week to airbrush craft acrylic paint thinned with Future polish (admittedly an several years old bottle of Future) didn’t turn out too well - luckily I was using some plain styrene sheets* as test media, no ruined models. Not sure if the air pressure was too high (25 to 28psi), the Future too old (I don’t think so), or the mix just wrong, but the finish was somewhat blotchy and lumpy, although after it dried it wasn’t too bad (it just wasn’t that good). Airbrushing craft paints thinned with Future right now, in Mythbuster speak, remains Plausible (Brush painting craft paint thinned with Future, OTOH, is CONFIRMED, especially with darker colors - the paint flows nicely and looks smooth when dried, like brush painting Floquil with the correct thinner use to. I hestitate to brush paint craft with light colors, as I don’t want cold hard reality splashing into my face - i.e. a blotchy, poor coverage rough paint finish).
Cleaning out the airbrush (again, prepairing for such a situation I used my back-up airbrush) was a PITA - Windex did nothing to clean the brush (still dried splotches left in the nozzle and feed tubes), I ended up using hot water, alcohol, acetone even, till the brush was clean of dried paint. Hmm, was Chris Chapman mistaken about this?
*As well as plastic spoons acquired at very steep discounts - the Matrix kid was wrong, there’s plenty of spoons…