Do you need to buy so many colors of paint?
Technically, you don't. But the more colors you have, the easier it will be to use the paints. Here's the thing: realistically, all you need to create ALL of the colors of the rainbow are the following colors: red, yellow, blue, black, and white. From these colors, all other colors can be mixed. But the thing with doll repainting is that it's really necessary to apply 3-4 thin, watered-down coats of paint, as opposed to one thick, goopy coat that shows brushstrokes. So, if you mix the correct color on your palette and apply one coat of it to your doll, chances are that it will dry on your palette before you have time to apply a second coat to your doll. Of course, you do have the option of mixing the paint on your palette with the Retarder, and the retarder will slow the drying time, but it probably won't slow it enough to allow you to apply more than two coats to your doll. Sure, you can mix the same color on your palette again, but the odds are that you're not going to get it to be exactly the same color as the first time that you mixed it. So by having more colors at your disposal, you can use them straight out of the bottle, and therefore avoid any frustrating drying time issues.