Many decorators make their own petal dust by grinding nontoxic chalk or pastels into a fine powder. Though chalk and commercial petal dust don't have the same chemical composition, they're similar. Homemade decorative dust is safe to have on and around products that people will consume, but it's best not to eat it in large quantities. Decorators should use chalk-based dusts on embellishments not intended for consumption.
Purchase chalk or artist pastels in the shades desired. Make sure you get non-toxic products. You can choose sidewalk chalk or high-quality sketching pastels and chalk.
Lay down a sheet of wax or parchment paper on which to work, if desired.
Break the chalk into small chunks.
Place the chunks in the mortar. Grind it with the pestle. You want a very fine powder that, when mixed with liquid, will form a smooth paint.
Sift the powder through a tea ball, to ensure it's fine and even.
Tear a small sheet of wax or parchment paper. Pour the powder onto the sheet. Place the powder in a storage container by funneling it from the paper.
Wash all the grinding and sifting tools You need to remove all the powder from the previous color, so it doesn't end up in the next color you grind.