Old/New Golden Additive in Tips & Advice: Painting Posted February 20, 2007 Golden's additive GAC 500, it was originally sold as a self leveling acrylic additive for their fluid acrylics. Here is the specs from their web page, without the update for the relabel. GAC 500: Self Leveling Applications / Hard Yet Flexible / Best Isolation Coat Medium for Spray-Application. Unique balance of film hardness and flexibility. Mix 2 parts GAC 500 to 1 part Airbrush Transparent Extender to produce a good spraying, fast-drying isolation coat. Beneficial as an additive for acrylic paints for increasing mar resistance and decreasing dry film tack, without disturbing the balance between hardness and flexibility. Useful when working on flexible or rigid supports. Offers a self leveling working quality. Dries to high gloss film with good clarity/transparency. Useful to hard-edge painters to seal masking tape for cleaner edges. Apply over masking tape. Let dry before applying additional paint layer. They are now relabeling the bottles. This is why I picked up this product, the new label says "Fluid Acrylic Extender". Which sounded like it would work great for some of my airbrush work, and possibly use it for mini's but wasn't sure. This product is a great thinner for the RMS paints, I mix it about 3:1 or 4:1 paint to thinner, no water needed(and haven't tried with any slow dry yet.) If you wanted to try with a slow dry, Golden recommended (I called them to find out if I got a mislabel or what) their Acrylic Glazing Fluid as it has their retarder included. It is pretty much nothing but pure acrylic medium, of a very high quality. I have used other ones like this, but had them change the color on the paint for some reason, this does not affect the tint or hue of the paint at all. The only down side I have found so far is if you mix to much with the paint, it looses any covering power at all, going almost completely transparent. And it does dry glossy, but that can be knocked down with dullcoat of course. Just though I would post this as the relabeling has really just started.