dross

Etymology

From Middle English drosse, dros, from Old English drōs, an apocopated variant of Old English drōsna, drōsne (“a ground, sediment, lees, dregs, dirt, ear wax”), from *drēcg + -sn, from Proto-Germanic *drōhsnǭ, from *dragjō + *-snō, ("yeast, sediment"; compare *dragjō (“yeast”)), from Proto-Indo-European *dʰrā́ks (“sediment, yeast”). Cognate with Scots dros, drose, drosse (“small particles, fragments, dross”), Middle Dutch droes (“dregs”), Dutch droesem (“dregs”), German Drusen (“lees, dregs”), Latin fracēs (“grounds or dregs of oil”). Related also to drast, dregs.

noun

1. Waste or impure matter.
2. Residue that forms as a scum on the surface of molten metal from oxidation.
3. The impurities in metal.
4. A waste product from working with metal.
   Dross is related with the incomplete expulsion of the melt from the bottom of the kerf. For precision applications where the clean cutting edges are important the formation of dross at the bottom of the cutting kerf must be controlled. This requires deep understanding of the mechanisms of dross formation and the various materials and laser-cutting parameters which potentially control the formation of dross. For example, the highly cleaned (dross-free) cutting edges can be obtained in […] 2008, Narendra B. Dahotre, Sandip Harimkar, Laser Fabrication and Machining of Materials, Springer Science & Business Media, page 176
   One of the main problems with recycling and melting magnesium is the presence of particles in the melt which lead to the formation of dross and sludge. To be more precise, the necessary removal of dross and sludge greatly increase the costs of the facility. And, material is lost. 2008, André Ditze, Christiane Scharf, Recycling of Magnesium, Ditze & Scharf, page 25
5. (figurative) Worthless or trivial matter.
   What thou lovest well remains, the rest is dross c. 1945, Ezra Pound, Canto LXXXI

verb

1. (transitive) To remove dross from.