This DIY sugar scrub uses gel food coloring, which I assume is gel paste food coloring. Gel paste food coloring is more expensive than the cheap liquid food coloring you may be used to, but you only have to use a bit on the end of a toothpick for amazing colors – so the gel paste food coloring lasts forever. Wilton makes it and you can buy it at Michaels with a coupon.
Liquid gel gives a deep, rich color without thinning and blends well. It is available online and in specialty stores.
Liquid is the most familiar form of food coloring. It gives the weakest color compared to other types of food coloring and, because of its liquid consistency, it will thin out whatever it is being mixed with.
Gel-paste gives deeper, more vivid colors than gel or liquid. It is very concentrated and should be used in very small quantities.
Powdered Food Coloring
Powdered food coloring is very concentrated. It can be combined with sugar to decorate cookies, and with lemon extract to paint onto iced cookies (just roll cookies in it to color them).