What is the purpose of blocking during surfacing?

• A. To hold the lens in place through the entire surfacing process.
• B. To color the lens.
• C. To apply lubricant.
• D. To shape the bevel.

Answer: (A)

Blocking provides a rigid mount for the lens on the surfacing machine. The lens must stay fixed during grinding and polishing, because even tiny shifts can change the final power and decentration. By attaching the lens to a block with blocking material, the whole assembly can be securely gripped and rotated, keeping the lens properly aligned throughout roughing, finishing, and polishing. This secure hold ensures uniform material removal and reduces the risk of slippage or breakage. Blocking is not used to color the lens, apply lubricant, or shape the bevel.