In the galvanizing production line, Zinc Dross is produced on the zinc bath’s surface which will be detached and put in a dross container.

According to the ISRI Specifications, Zinc Dross is divided into four types:

• Hot-Dip Galvanizers Slab Zinc Dross (Batch Process) [ISRI Code: Scrub]: Shall Consist only of galvanizers unsweated zinc dross in slab form from hot dip galvanizing (Batch Process) with a minimum content of 92% and shall be free of skimmings and tramp iron.
  • Broken pieces under 2” in diameter shall not exceed 10% of the weight of each shipment
  • Slabs shall not weigh over 100 pounds each.
  • Material from a continuous galvanizing operation is acceptable.
• Continuous Line Galvanizing Slab Zinc Top Dross [ISRI Code: Seal]: shall be consist of unsweated zinc dross removed from the top of a continuous line galvanizing bath, in slab form not weighing in excess of 100 pounds each, with a minimum zinc content of 90%.
  • Shall be free of skimmings 
  • Broken pieces under 2” in diameter shall not exceed 10% of the weight of each shipment
• Continuous Line Galvanizing Slab Zinc Bottom Dross [ISRI Code: Seam]: Same as Continuous Line Galvanizing Slab Zinc Top Dross, but the zinc dross is removed from the bottom of a continuous line galvanizing.
• Prime Zinc Die Cast Dross [ISRI Code: Shelf]: shall consist of metal skimmed from the top of the pot of molten zinc die-cast metal.
  • Must be unsweetened, unflexed, shiny, smooth, metallic and free from corrosion or oxidation
  • Should be poured in molds or in small mounds weighing not over 75 pounds each