What You Need to Know About... Polished Edges

By Russell A. Gagain, LO, ABO, NCLC
Remember when you had that -7.00 dioptor CR-39 rimless job that came into the lab? Did it make you wonder why the frame stylist or optician didn’t like that person. You just knew that these lenses would be too thick and look cosmetically awful. Then you looked to see if at least a polish was ordered.

This thinking is not so critical any longer now with the new lens materials such as 1.67. The appearance of these glasses is so much nicer. Materials are not the only tools we have to improve the cosmetics of these types of glasses. As tradition holds, there has always been the “roll and polish” for reducing edge thickness, but also for improving the edge appearance.

This edge appearance can be achieved in many ways and to varying degrees. A variety of dynamics can produce a wide range of results. These factors can be, but are not limited to: lens materials, types of bevels, equipment manufacturers, wheels – edger and buffing, motor speeds, water flow, fresh or bucket water, as well as any additional compounds introduced during the polishing cycle.

Additional processes may still be required such as taking the lens to the polish “wheel” or the “buffer” to buff out the edges. This is an art form in many labs. In addition to this art form, precautions are required to prevent front and rear scratches by protecting the lens with surface saver tape, or lens dots like the 3M Blue Chip Lens Protectors.

The traditional terminology of a “good” polish is insufficient to describe the quality of the edge appearance. This subjective inspection requires a comparison and is reliant on experience. Is it too shiny, too dull, are there lines? I believe finish edging polish quality should be standardized for this industry. I propose a polished lens standard that incorporates a common G Edge Scoring System.

The polish criteria can be viewed as shown in the table below by three levels; Status, Polish Type, and Polish Quality. Within each category there is an opportunity to score a number based on that level. The scores from each level are then simply added together. The highest possible score per bevel type (Bevel & Flat) is a seven.

This would give you a polished, super sheen edge, with no noticeable defects. This is commonly referred to as “Glass-like.” The lowest possible score would be a zero. This would give you a non-polished edge. The Polish Type and Polish Quality classifications are the most important factors. Ideally, the edge must be polished, super sheen, with no noticeable defects. See pictures 1 and 2 for a comparison. Your lab should test the material range, type of edge, bevels, flats, type of polish, and the polish quality. Test the edge polish of materials 1.498 through 1.67. These need to be processed during your testing for baseline and actual testing. The score will reflect the “better/best” on a more definitive basis.

Written by: Russell A. Gagain LO, ABO, NCLC, and Product Specialist Gerber Coburn. He can be reached at 860-648-6600 or by e-mail at: Russ.Gagain@GerberCoburn.com

CURRENT ISSUE


May/June LabTalk 2017