How Are Our Glasses Made?
Prescription glasses, they may be everywhere, a must for many people to read, watch tv, or drive, but the process that each pair goes through is very complex. Much more than adding a lens into a frame, there’s cutting, moulding, boring, riveting and lens crafting. Here’s a brief look at how prescription glasses are made and how far they’ve come before they are delivered to your doorstep. We’ve focused on acetate glasses in this article but metal glasses are made in a similar way.
The first step on the journey to making your perfect pair of glasses is machining, where the frame fronts are cut from a large section of acetate (Acetate is a plant-based, non-petroleum product derived from wood pulp and cotton). After this, a cutting tool is used to cut a small channel in the lens hole so that later your custom lenses can be fitted perfectly to the frame.
Now, through counter boring, four holes are made in the acetate frame front so that rivets can be fitted and the hinges for the frame arms can be attached. It’s a tricky process where the recess depth needs to be perfect so that your frame arms open smoothly.
Once all the fittings have been expertly fitted, your frame fronts are heated and pressed into a mould to curve the frames, making them comfortable to wear and allowing the frames to be fitted more easily. To hold their shape they are then quickly cooled.
At this point, your frame may still be a little rough and have scratches from the previous stages, to polish and remove any marks, it is tumbled in a large barrel. After the friction polishing, your frames are ready for assembly!
Small high-strength screws are used to fit the frame arms to the front via sprung hinges. We make sure all our frames have high-quality hinges so opening and closing your glasses is a smooth and pleasant experience.
With your glasses frame finished, lenses crafted to your exact prescription can now be made. Each lens begins life as a ‘lens blank’, a piece of polycarbonate plastic (or glass) the size of a circular coaster. These lens blanks have different curvatures on one side and our lab technicians choose the correct amount of curvature for your prescription.
To shape the lenses, first, using a lensmeter, the ‘optical centre’ of the lens is found, this refers to the exact point that lines up with your pupil. Once the centre is found, the lens is covered in tape to avoid scratching and a blocker is attached to keep the lens in place during the grinding process. The flat back of the lens is ground into the correct shape.
After your lenses are correctly curved, they go through a series of polishing, beveling, and sterilization treatments, performed using a fining machine and several other tools, such as soft sandpaper. The block and tape are removed by hand after this phase. The final step in making your lenses is a process called edging, completed with an aptly named edge grinder. This grinds the lens into the final shape needed to fit perfectly into your chosen frame and a bevel is placed around so that the lens fits tightly into the frame.
If you’ve chosen a tint/coating (UV, anti-reflective or anti-scratch are available for a small charge) your lenses will be dipped in a coat and are then ready to be placed in your frames.
Before you receive your custom prescription glasses, our lab runs through stringent quality control measures, these include:
- Checking for scratches, dents, chips, and cracks.
- Checking the optical centre.
- Checking the prescription of the lenses matches your supplied prescription.
- Verifying the lenses have the correct coating or tint applied.
We make sure to provide you with a quality hard case and cloth with every pair of glasses. If you choose a designer frame you will receive the branded case and cloth also.
How long do glasses take to be made?
This largely depends on the frame type and whether it is a designer frame or if it a small boutique batch. Depending on the level of automation, a frame can be ready within 5-7 days, most of our frames are pre-made and the production time is almost entirely spent on crafting your custom lenses which can take the same 5-7 days to complete.
How were glasses made historically?
It’s hard to pinpoint the exact origin of glasses used to improve vision. There are mentions of “reading stones” in Greek texts that are traced back to the 10th century. These would have been hand-carved to very basic and round shapes and were most likely made of two separate lens holders, similar to two magnifying glasses joined together.
If we try to find the very first glasses that we would actually recognise as glasses, we’d probably end up in Italy around the 13th century. The designs found from this time consist of a metal frame with two glass stones which would be held up when reading.
Since then, glasses have become increasingly more popular and technology has constantly evolved, with bifocals, lenses for correcting astigmatism, and even eventually contact lenses being made. The college of optometrists has an informative podcast about the history of the earliest spectacle frames. Why not listen to it now?
Glasses today are almost as much a fashion statement as they are a necessity, as they come in a large variety of shapes, colors, and sizes. Browse our ever-increasing range of frames.