You must not throw it away.
One can the fine enamel dust use for enamel painting. But you must grind it in a mortar until it is really so fine as flour. Then you can mix it with an Acrylic-painting liquid. These liquid you get by Thompson enamel or in an art supplier-shop. If the Acrylic liquid is to thick, you can thin it with water. Acrylic-painting-liquid is much easier to handle than painting oils like Lavender- or roseoil.
An other possibility is to use the fine-powder as conter-enamel. Instead of sieving , you can apply it wet. If you the fines use, it may be, that, during the firing the enamel surface fracture like craquelé. Apply a second shift of enamel and fire again. Usually, the cracks disappear.
 If you sort the fines by colors, you have allways a correspondending color to the frontside, especially if you make jewellery.
Edmund

I'll try it!  I didn't think about the color correspondence with the front side.  I will try and wetpack the back side with fines mixed with holding agent and see how it fires.

Thanks, Lillian

Hi All,

I've been grade-sifting my old Thompson enamels to clean them for my wet-packed cloisonne.  As a by-product, I have ounces of leaded fine powder.  This stuff strikes me as very poisonous in a dry form, as it wants to float in the air. There is no way I'd use it for counter enamel, it is like dust. (I only use unleaded for sifting)

Is there a use for it? Would it make an opalescent if fired, or a painting enamel?  Or should I throw it away?

Lillian Jones