Knowing the Material
Let’s start with the most basic question: What, exactly, is gold luster? Luster is an overglaze, meaning that it’s applied over the vitrified, glaze-fired piece and requires a third firing. Luster is made of particles of real gold suspended in a liquid medium, usually a pine oil resin. After being applied to your piece, it’s fired in order to burn off the organic binder. What remains is a layer of real, melted gold on your piece. This is very different than gold leaf, which is applied with adhesive and isn’t fired; lusters are permanently fired onto your piece.
You can purchase lusters (including gold, silver, platinum, mother-of-pearl, and more) from local clay suppliers and various online sources. If you end up loving the shine that it adds to your ceramics, I would advise checking with your supplier to see if they offer bulk discounts. I use Duncan lusters not only because they work well and are easy to find here in the US, but also because they offer discounts when I order a dozen bottles at a time. Gold luster isn’t cheap, so it’s definitely worth looking into. When ordering, keep in mind that each bottle (1) is tiny—only 2 grams—but it will probably go farther than you think. I’ve read that a single 2-gram bottle will cover a 12-inch tall vase entirely, of course, how large or rotund that vase is would be anyone’s guess. For my use, if I’m only adding gold accents to the flowers on my mugs, I find that the bottle lasts a long time. But, if I’m covering the entire handle on a set of large mugs, the bottle doesn’t last for more than 5–10 handles (2).