Tom, it might be possible that you didn't shake the Micro-flat enough so some of the flattening agent was still settled in the bottom of the bottle. But it looks like you found a workable alternative.
Even though I shook it for a full minute (timed it) before using it, I double checked with a mixing stick after I had the problem, to double-check. I see no evidence of anything stuck at the bottom. I did have to thin it a little (used a 50-50 mix of alcohol and water to thin it) in order to get it to spray, but just enough to get it to go through a #3 Paasche tip.
So...a mystery to me. I will assume that it must usually work - or it would no longer be on the market. But as you say, I found a workable alternative, so I will stick with the Modelflex product in the future. My observation is that Modelflex has made progress on product quality in recent years, both in terms of how it sprays, and consistency of color.
