The Journey of a Spectacle Lens

If you wear glasses, you're no doubt familiar with the process of ordering glasses to suit your prescription needs. However, have you ever wondered just how the lenses are made? There are a multitude of different processes that go into the manufacture of a lens.

In this guide we have outlined 13 of the most common ones, but depending on the lenses you have chosen, there may be up to 20 processes involved!

STEP 1: Order Receipt in our Laboratory

It all starts here, where your order gets processed in our laboratory admin department. The staff input your prescription into the system and your frames are scanned for size and shape.

STEP 2: Starting with a 'Blank'

They begin their life as large, thick chunks of rounded plastic called 'blanks'. The blanks can be up to 3cm thick in some cases!

The type of blank chosen will vary depending on the lenses selected at the time of ordering. Different blanks are available for single vision, bifocal or varifocal lenses and will also vary depending on whether thinner (high-index) or light-sensitive (Transitions) lenses have been ordered.

STEP 3: Taping

 

The blanks are flat and rough on one side (the back) and smoothed to a particular curve on the other (the front). As the untreated plastic is prone to scratching, we protect the curved surface by taping it with protective adhesive tape.

STEP 4: Blocking

 

The lenses then get passed to a blocking machine. The blocking machine uses hot liquid metal to fuse a small button (known as a 'block') to the rear side of each lens blank. This is what holds the lenses in place during the grinding and polishing processes later on. The lenses are then left to cool, before being taken to a generating machine.

STEP 5: Generating the Curve

 

Our generating machine has a control panel where your prescription details are entered. Your lenses are then placed onto an 'arm' one at a time, which then pulls the lens into a grinder behind a protective screen. The grinder then uses your prescription information to quickly and accurately grind the correct optical curves into the back of the lens.

The curves at this point feel rough to the touch, so the lenses are then taken to be smoothed and polished.

STEP 6: Smoothing

 

In our smoothing and polishing department, there are hundreds of 'metal smoothing laps' which are metal molds that smooth down the newly-generated curve in your lenses. There is a particular metal lap for every possible curve, so as you can imagine, there are quite a few to choose from! The technician attaches a fining pad (which feels like sandpaper) to the corresponding lap, which is then used to sand down the curve and smooth it.

STEP 7: Polishing

To polish the lens, a different velvet-feel fining pad is attached to the lap instead of the sandpaper one. The machine then repeats the process, but this time, polishing the surface instead of smoothing it.

STEP 8: Cleaning

Your lenses are then taken out of the machine and dipped in a cleaning solution. It's at this point that the blocks attached in step 4 are removed from the back of the lens. The metal is recyclable, so it is immediately melted, ready to be used again. As for your new lenses, the protective plastic is peeled off and the lens is checked thoroughly.

STEP 9: Coating

Sometimes, your lenses will need to be sent for special coating (i.e. scratch-resistant, anti-reflection, etc.) which is outsourced. Once the lenses have been coated by the third party, they are given back to us to finish off, cut and dispatch.

STEP 10: Cutting

The next step is fitting your lenses to your chosen frame, which is done using our special automated cutting machines. These machines use the frame measurements that were scanned in step 1 to cut the lenses to the exact shape and size.

 

To secure the lens during cutting, a plastic button is attached to it that slots into the machine and holds the lens in place (similar to the metal block in step 4).

The measurements mentioned above are automatically pulled through from the customer database, then at the push of a button the machine comes to life and works on the lens, cutting it down with amazing accuracy.

STEP 11: Bevel

For rimless and semi-rimless glasses, special holes are machined into the lenses at this point.

 

Once cutting and shaping has been completed and any necessary holes have been put into place, the lenses then get taken to another part of our lab where the sharp edges are smoothed down to create a blended bevel.

STEP 12: Tinting

If necessary, the lenses are then dipped in their required tint colour and left to absorb the dye. Timing is crucial at this stage as the longer they are left in the tinting container, the darker they go.

STEP 13: Final Checking and Dispatch

The lenses are checked against the prescription and order details in the final stage to ensure accuracy. Once we're sure they are correct and they have been put into the frame, your glasses are packaged and dispatched to your branch.

 

When you come in to collect your brand new specs, one of our trained staff members will help fit your glasses properly to ensure maximum comfort.

So there you have it; the journey of your spectacle lens!

From our branch, to our lab and then to you; Direct Specs aim for accuracy, comfort and professionalism every step of the way.

 

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