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A blocking pad is a small, specialized, adhesive sticker used in optical labs. It is placed directly onto the surface of a lens blank before the lens is mounted onto the block. The pad is needed to protect the lens coating and to firmly secure the lens during the grinding process.
read more about blocking pad in optical labs ...The pad has two important roles. First, its sticky surface provides the necessary grip to hold the lens firmly to the block during high-speed surfacing or edging. Second, it acts as a soft protective barrier between the hard block and the delicate coatings (like anti-reflective or anti-scratch) on the lens surface.
Blocking pads are typically made of soft vinyl, rubber, or specialized foam with a strong, yet temporary, adhesive on one side. They come in various shapes and sizes to fit different frame shapes and lens curvatures.
A high-quality blocking pad prevents slippage during the grinding process. If the pad allows the lens to shift, the lens will be cut inaccurately. A good pad also makes sure that when the lens is later deblocked, the adhesive removes cleanly without damaging the lens coating.
Pad protection safeguards your backup glasses. Since the blocking pad protects the lens coatings, it helps make sure your glasses maintain maximum clarity and durability. This protects the quality of your vision correction when your contacts are removed.
No, blocking pads are designed for a single use. The adhesive must be strong, and the pad must be replaced after the lens is deblocked.
No, skipping the pad would directly damage the lens coating and prevent the block from holding the lens correctly during surfacing.
Yes, a pad is often placed between the lens and the molten alloy to provide protection and help the alloy stick evenly.
Blocking pads are essential for protecting premium anti-reflective coatings. If your brand-new glasses appear to have "peeling" or "crazing" in the center, the lab may have used an incorrect pad. A doctor can use a slit-lamp to determine if the coating is compromised.
Review of Optometry. AR Coating Durability (reviewofoptometry.com). 2024.
The Vision Council. Surfacing Equipment Standards (thevisioncouncil.org). 2023.
ABDO. Practical Lab Techniques (abdo.org.uk). 2024.
Optical Laboratory Association. Surfacing Guidelines (ola-labs.org). 2024.