No I have not tried that. But I’m pretty sure that it would work. Tamiya flat clear base was originally marketed as an additive for their gloss paints to turn them into flat colors as needed. And I have added the flat base to Future to make that into a flat top coat. That worked just fine. But you don’t want to go above a 25% flat base to 75% Future ratio. A higher percentage of flat base and you’ll start getting real chalky/cloudy on the top coat. Experiment first on a paint mule to get the finish look that you want.