Troubleshooting Tips
Tinting: Types and Tips
by Karlen McLean, ABOC, NCLC
Q WHAT ARE THE OPTIONS AND ISSUES INVOLVED WITH TINTING?
A It's important to be aware of the amount of space needed to effectively employ a tint station; most tinting areas need access to outdoor ventilation, and multiple pots are needed to offer the variety of colors that today's consumers demand.
When setting up a tint station, pay attention to the pre-cleaning process. All lenses must be thoroughly prepped prior to tinting.
As for systems, one of the most advanced tinting is BPI's Turbo Tinter II, which features an infrared heat source that allows for more temperature control with digital temperature readouts. The system also uses self spinners in each beaker to help maintain temperature consistency and create agitation, which eliminates settling.
Other units use a series of multiple stainless steel tanks in varying sizes that heat dyes with a heat transfer fluid. Some systems integrate computer controls to monitor dye bath temperatures, and many others use either manual or automated gradient dip controls. On the less sophisticate side are systems that heat dyes in a microwave and others which simply use beakers and hot plates.
Results are typically consistent with the level of technology used. Dyes are available in an almost limitless number of forms. Most labs use concentrated liquid dyes that offer greater consistency and create more uniform colors.
Other forms include pills, caplets, and powders. The combination of dyes and mechanical equipment is a critical component to a successful outcome. Certain dye forms tend to work better when combined with certain systems.
When tinting poly, apply a layer of soap to the lenses to eliminate bubbles caused by surface tension. A quality, full-service lab is your best partner in building a state-of-the-art tinting department.
—Jeff Szymanski, vice president, Toledo Optical Laboratory, Toledo, Ohio EB
| Topnotch Rimless Lens Tinting | |
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Q When tinting rimless lenses, what's the best way to prepare the edges of each lens material (CR39, poly, high-index, and Trivex) to accept the tint and look its best? A Consider how dark the tint needs to be. Many finished lenses lean more toward scratch resistance than tintability. Finished lenses that are extremely scratch resistant are often non-tintable. Usually, if the Rx calls for medium to dark tint density, it's best to grind a semi-finished lens that employs a tintable backside coating. When it comes to poly, high-index, and Trivex, you are only tinting the thin scratch coating on the surface. Especially on poly, the tint is not absorbed into the substrate. This poses a problem for tinting, for instance, if the Rx calls for poly lenses with a rolled and polished edge. When the lens is rolled, the scratch coating is removed on that part of the lens. When the lens is tinted, the dye can't be absorbed into the exposed raw poly substrate on the rolled part of the edge. The same thing happens when a pin bevel is applied to the edges. This is called white ring effect. We try to apply the lightest, thinnest safety bevel possible to dark-tinted lenses made of these materials. A heavy safety bevel will surely result in a white ring around the lenses. Rolled and polished lenses should have a very light roll or be avoided all together. All tinting should be done last because it will eliminate any white ring effect completely on plastic lenses, will help even the tint on high-index, and help somewhat on poly. Poly is the least tintable substrate in the marketplace and thus poses the biggest problem with white ring effect. —Mike Sutherlin, vice president, Sutherlin Optical, Kansas City, Mo. | |
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