A professional who tends blocking machine that seals optical or ophthalmic lens blanks in metal blocks preparatory to grinding and polishing of lenses. Responsibilities include:

• Applies lacquer to lens blank, using spray gun or brush.
• Mounts lens and block in blocking machine, aligns marks on lens blank and block, and clamps lens and block in place.
• Pulls lever to admit molten pitch or metal alloy and water through holes in block and starts machine that bonds lens blank to block.
• Pours molten pitch or loads solid metal into machine to replenish supply.
• May tend machine that casts metal block and bonds lens to block in one operation.