HANDS ON - Lens Tips
Tint Checks
by Karlen McLean, ABOC, NCLE
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Tinting for function makes sense. Images courtesy of BPI |
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Fashion is awash in color right now. Bright colors are trending throughout this year. You can fashion-up your lens tint offerings by watching runway trends and duplicating what you see there.
Ask sunwear, ophthalmic lens, and tint manufacturers what color trends they see now and are gearing up for. And don't forget that tinting for function--be it medical or task-specific use--never goes out of style.
Get the most from your tinting equipment and hone your tinting techniques with these tips.
Mix tints with distilled water, not tap water, to avoid mineral contamination in the tints which can cause color deviations. If you must use tap water, let it sit in a container overnight to allow the minerals to settle.
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problem/solution |
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Here are four all-too-common tinting problems and what causes them. Streaks can result from using old tint solutions, not stirring the tint regularly, tint contamination from the heat transfer fluid, residue on lens holders, and varying lens hardness. Pitted lenses are caused by invisible weaknesses in the lens, which repeated tinting and neutralizing or exposure to heating/ cooling can compromise. Color variations can be caused by tap water. Blotching is typically caused by tinting a heavily cured lens. |
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Stir and mix tints well on a regular basis.
Change tints if lenses begin to come out blotchy.
For matching as well as color corrections, keep red/pink, yellow, and blue tints on hand.
Before emptying a used bottle of tint, shake it thoroughly and rinse until the water runs clear.
Shelf life on tints is usually six months, so don't buy the economy-size bottle unless you know it will be used before the expiration date.
Edge and cut lenses to the frame before tinting. Otherwise, the unattractive light edge can cause reflective glare.
Temperature of the tint unit should be kept between 190 and 200 degrees Fahrenheit for standard plastic lens fashion and gradient tinting.
Gradient tints will be smoother if you occasionally adjust the L-rod at the nylon swivel about 5mm to change the grade of the lens.
Immersion of lenses in tint or neutralizer should be no more than half an hour. Change the tint if lenses need to be immersed longer to achieve the desired color.
For pairs, don't mix surfaced and stock lenses, lens types, varied coatings, or a combination of coated and uncoated lenses. Also, use lenses from the same manufacturer, preferably from the same batch number.
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Immerse lenses in tint or neutralizer no more than 30 minutes |
Clean lenses completely and make sure they are free of all ink markings, oil, debris, and fingerprints before tinting.
Increase time of tinting, but do so carefully, when working with lenses that have "non-tintable" coatings on the front-side or backside.
To avoid problems and achieve the best tints, create your own tint standard. Starting with fresh tints, tint a sample lens of each color for about 15 minutes. Clean the lenses, and then set them aside in an area where they won't be exposed to light.
Test future lenses against them to make sure they are acceptable to that standard.
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material matters |
| Tinting Polycarbonate Poly material is typically tint-resistant. Built-in scratch-resistant properties mean you're tinting the scratch coating as well as the lens. While most poly is not as tough to tint today as it was a few years ago, there are still some pointers for the best poly tint results. 1. Check your tint unit for uniform and exact heating, including checking the heat transfer fluid. Make sure tint tanks are properly immersed and that the fluid is fresh (check your owner's manual). The unit needs to maintain high, even temperatures for poly success. 2. Operate with a tint temperature between 205 F to 210 F. Check temperature with a quality laboratory thermometer. 3. Tints should be stirred constantly for the best tint color, adhesion,and consistency. Some units feature automatic stirring features. 4. Be sure lens pairs to be tinted are from the same source, preferably the same batch number. 5. Avoid exposing lenses to high levels of humidity prior to tinting. Keep lenses in trays away from the tint unit to avoid moisture from steam. 6. Clean lenses thoroughly and use a lens conditioner, if possible. 7. Immerse the lenses in the tint slowly, since immersing can cause the temperature to drop. If the unit doesn't automatically correct (some units have probes in each dye tank) and is slow to respond, the lens' hard coating can be damaged. 8. Shoot for tint density first and color second. Tinting Trivex Trivex material tints rapidly, as Trivex absorbs tints quickly. So it pays to be observant with Trivex lens tint immersion times. Here are a few of the top Trivex tinting tips. 1. Drop tinting temperatures to 160 F. 2. Reduce tinting times and watch tint density carefully. 3. Make sure the final polish on Trivex lenses is at least six minutes. 4. Apply a tintable backside hard-coating prior to tinting, or... 5. If directly tinting the backside, tint at 170 F to 175 F; tint in short intervals (approximately four to five minutes); rinse warm; and let the lenses cool in between immersions. Repeat as necessary. |
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