Hey Guys,
First time here and I love this site
Full disclosure, I'm the guy behind Model Paint Solutions and the AB cleaning article previously mentioned.
The turning coin is an apt pic for this discussion
. I will try and be succinct but that's not easy with this subject.
I've gotten into trouble before by answering this question bluntly and honestly and the most outraged emails usually come from AB distributors and/or Reps. In addition, the complete answer is nuanced and social media prefers sound-bites of yes/no, black/white. Okay, here we go:
Windex can be used without harming the finish (and this is really the important point)----IF IT IS NEVER ALLOWED TO DRY IN THE AIRBRUSH!!
There is a caveat to this so please keep reading. Electroplating is affected as the ammonia in the Windex dries. So, if you remember to rinse the Windex out (fanatically) as part of your cleaning routine, it won't hurt your brush. Now here's the caveat,
some AB brands have better plating than others. Not all AB's are created equal. That being the case, the brands with good plating resist corrosion better than those that don't. Being an AB junkie from an early age, I've owned most (all?) of the major brands of AB over the last 40 years and, most importantly,
I regularly repair H-S, Iwata, Skybow, Higher-end Iwata Knock-offs, Grex, Paasche, Badger, and the occasional Thayer&Chandler as part of the AB services offered on MPS. I see what these brushes look like after years of use and if I've worked on your brush, you know that I regularly ask about the type of paints and cleaning routines used via email exchanges before beginning a rebuild. I've also witnessed the effects of long-term Windex use on my own brushes and it's a mixed bag.
Bottom line:
1) Brushes like H-S, Iwata, and some of the higher-end knock-offs withstand Windex well enough that the occasional lapse of memory leading to Windex being left in the cup to dry, doesn't lead to a loss in plating.
Now, do that every day and yes, you'll start loosing plating no matter what AB brand you're using.
2) Brushes like Badger, Paasche, and Grex and most of the lower-end knock-offs, don't withstand exposure to Windex as well. I say this based on repairing them and owning them. This means that with those brushes you have to be more careful to rinse out the Windex during the cleaning routine as it only takes a couple missteps to start loosing plating.
NOTE: A final 5 minute soak in water or your favourite acrylic thinner as the last step of your cleaning routine should be sufficient to remove residual Windex. Note that I suggest a
5 Minute SOAK. It takes time for the last rinse of water/thinner to permeate the threads and crevices of the brush and displace residual ammonia. The very last step I use with my brushes is a 5' soak in Tamiya Airbrush Cleaner (Square bottle/Pink Top); good stuff.
Since, for some brushes, you have to be more careful when using Windex for cleaning, it's important to balance that with the upside of why it's an efficient cleaner. Many acrylic paints utilize thinners that are either alcohol- and/or ammonia-based. That being the case, a combination of Windex and IPA (Isopropyl Alcohol; the highest percent you can get from the grocery store/pharmacy) mixed at a ratio of 1:1 (50% Windex/50% Alcohol) is a very efficient cleaner for most acrylic paints even when the paint has dried. It is also very cheap Vs the "Airbrush Cleaners" made by the big manufacturers and,
with careful use and that final soak/rinse, can be used for many years in most brushes with no issues.
Sorry for the long response but as I said in the opening, the complete answer requires some nuance.
I hope that helps.
Cheers!
--John M.