For professionals in the eyewear industry, spectacle lenses are part of daily operations — from choosing the right specifications to ensuring accurate vision correction. While you may understand lens parameters like Abbe number or refractive index, the actual spectacle lens manufacturing process remains unknown to many. At ReOptical, we believe that transparency builds trust. That’s why we are sharing an in-depth look at how a lens is made, step by step, in our facility.
As one of China’s trusted lens suppliers, ReOptical uses a 12-stage production process to ensure each lens meets strict quality standards before it reaches our international clients.
Step 1: Material Mixing and Preparation
Production begins with mixing raw monomers with specific additives. Different types of lenses require different formulas — for example, CR-39 is used for basic 1.499 lenses, while NK-55 is used for 1.56 index models. The mixture may also include pigments, antioxidants, and UV-absorbing compounds. The blended liquid is filtered, degassed under vacuum, and placed in casting tanks to prepare for molding.
Step 2: Mold Assembly Process
We use heat-resistant glass molds in two different assembly techniques. One method uses elastic rings to seal molds manually, ideal for standard-index lenses. The other uses single-use adhesive tape, applied via automated equipment. All molds are meticulously cleaned before use to ensure no dust or residue affects the lens formation.
Step 3: Casting the Prepolymer
The prepolymer solution — a combination of monomer, initiator, UV stabilizer, and mold release agent — is injected into the molds. This step must be done carefully to avoid air bubbles or overflow. The skill of the operator plays a major role in this critical stage.
Step 4: Thermal Polymerization
Once filled, the molds enter a controlled heating chamber. During this stage, the liquid inside slowly transforms into solid optical lenses through thermal polymerization. The process can last more than 20 hours and requires precise temperature programming based on the lens material.
Step 5: Removing the Mold
After curing, lenses are removed from their molds using compressed air. Sealing components — either rings or tape — are detached. The lenses are then separated from the molds, lightly trimmed, and cleaned to remove any remaining residues.
Step 6: Edge Shaping
The lenses undergo edge processing to ensure uniform thickness and clean outlines. A protective solution is applied beforehand to reduce surface damage during trimming. After drying, each lens is machined and checked for dimensional accuracy.
Step 7: Surface Cleaning
Ultrasonic cleaning tanks are used to clean the lenses multiple times. These tanks remove any remaining particles or chemical residues left over from the casting and trimming phases. Once this step is completed, lenses are ready for a second heat treatment.
Step 8: Stabilization Curing
This curing phase improves the mechanical properties of the lens. It helps to reduce internal tension and smooth minor surface defects. The heating time and temperature are controlled to match the type of lens being manufactured.
Step 9: Optical Quality Check
Now referred to as base lenses, the products undergo two stages of inspection. First, surface strength is tested with acetone. Then we verify optical details like lens power, center thickness, and refractive accuracy. Only approved items move forward.
Step 10: Pre-Coating Preparation
To ensure the upcoming coating layer bonds well, lenses are once again cleaned, then surface-treated for better adhesion. The procedure includes multiple drying steps and quality checks before moving to the coating process.
Step 11: Applying the Coating
A vacuum sputtering system coats each lens with a thin film of high-refractive metal or oxide compounds. These layers improve light transmittance and increase scratch resistance. ReOptical uses semi-automatic Korean machines and closely monitors thickness uniformity during the procedure.
Step 12: Coating Test
Each finished lens is tested for coating durability. Using a saltwater boiling method, lenses are immersed in hot saline solution to test for resistance to peeling and film damage. Any coating failures are corrected before the lens is approved for packaging.
At ReOptical, every lens is crafted through a consistent and well-regulated spectacle lens manufacturing process. From raw monomer to polished, coated optical products, our workflow is built for quality and reliability. With years of industry experience and a skilled technical team, we deliver lenses that meet the performance standards expected by optical professionals around the world.
Need a reliable spectacle lens supplier for your optical business? Contact us to discuss your wholesale or private label needs. Our team is ready to support your next project.
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