I had tried everything I could think of over the last several years to get Future/Pledge to airbrush consistently smooth.
My original reference was the Swanny's Models article all about it.
Sadly, the link seems to be defunct today: https://www.swannysmodels.com/TheCompleteFuture.html
I tried Isopropyl Alcohol, Windshield washer fluid, distilled water, Simple Green, and maybe even Mr Color leveling thinner.
All of them gave inconsistent results. The results were sometimes rough/pebbly and sometimes it would crawl and pool up on me.
So, recently, I swore I would stop trying and use clear coats made for models going forward....but I'm a cheapskate!
I tried one more time!
I used this flow aid at about 30-40% ratio and it airbrushed/atomized well. The result was really smooth and nice...smelled good too!
I'll let you know if the results are repeatable but I'm encouraged to try again. I bought this stuff at a craft store, Michael's.