Vallejo also has a Drying Retarder. "To delay drying time of Model Color, mix a few drops with the color, or dip brush into retarder on the palette. Colors will not change their consistency. Useful for “wet on wet” techniques and reducing skin formation on the palette." 70.597 Bottle 17 ml. and 73.597 Bottle 60 ml.
Airbrush Thinner: "Thinner for Model Air and Liquid Acrylic. Thinner used to extend the colors, to increase fluidity and delay the drying time. We recommend the addition of a few drops of thinner to the colors while airbrushing." 71.261: Bottle de 17 ml. and 71.061: Bottle de 32 ml.
Airbrush Flow Improver: "Medium designed to improve the flow and delay the drying of paint on the needle while airbrushing. It is recommended to add 1-2 drops of Flow Improver to 10 drops of paint in the cup of the airbrush." 71.262: Bottle de 17 ml. and 71.362: Bottle de 32 ml.
Very confusing; I think Vallejo is just trying to increase their revenue so I'm just going to use the Thinner.