DARK VISION
PROBLEM: When processing polarized sunlenses, I have a hard time seeing my lens markings during the centering and blocking phases. What can I do to make them more visible?
SOLUTION: In many instances if the blocker used in the finishing operation does not have the proper illumination or the ability to increase the illumination of the centering grid, errors may occur.

A suggested solution is to make clearer marks on the lens with a marker or to buy a new blocker which addresses this problem.

-Matthew Vulich, vice president-sales, AIT

SPLOTHCY COLORS
PROBLEM: We have a hard time tinting sunglass lenses because the color turns out splotchy. What can we do differently to prevent this uneven coloration?
SOLUTION: Splotches can occur when the lenses haven't been treated, or prepped, before tinting. Commercially available lens preps are a good idea.

You can also make your own lens prep by mixing a couple of ounces of neutralizer into a dye pot of distilled water. Dip the lenses into this solution for approximately a minute before tinting to open the pores of the lens and allow it to accept the dye more easily.

-Stuart Watson, training director, National Optronics

OFF-CENTER LENSES
PROBLEM: Our lab cuts a lot of coated sunglass lenses. We have a hard time making the lenses cut out right. For some reason, these jobs seem to come out off-center a lot more often than clear lenses. What can be causing this?
SOLUTION: Blocking a lens for edging using computerized equipment can cause problems if the lenses are mirror-coated or very dark because the major reference points can be difficult to find.

The three dots on a single vision lens or a multifocal seg can be hard to see on an LCD screen.

The answer is to edge the lenses first, before coating them. You also save money by coating afterwards because you're not using so much coating per lens. A little coating on each lens adds up to a lot over time.

-Michael Urban, product manager, Gerber-Coburn

Hush Puppies styles (left to right) Zapp, Zipp, and Zing for Lancer International

INCONSISTENT COLORS
PROBLEM: Our sunglass tints don't always come out the same way twice. How do we make the color consistent from one job to the next?
SOLUTION: There are several things you can do. Lens preparation is the most important thing. Make sure the lens is clean and that any ink markings are completely gone. Inspect the lens to be sure that there are no abrasions.

Once you've done those things, the lens should be clean and dry before you start the tinting process so that it will be more absorbent and the tint won't run.

-Kevin Wise, technician, LOH Optical

LOOSE LENSES
PROBLEM: Several patients have brought in sunglasses that they purchased elsewhere and asked us to put Rx lenses into the frames. When we do it, they come back and complain that the lenses keep falling out. A couple of times we've super-glued the lenses in, but that turned out to be a mistake. What are we doing wrong? 
SOLUTION: If someone brings you drugstore sunglasses, they're probably not ophthalmic frames. The bevel in a non-ophthalmic frame isn't deep enough to accommodate an Rx lens, which is why the lenses won't stay in place. Make sure that when you're edging lenses, they're going into an ophthalmic frame.

Using super-glue to keep the lenses in can be a disaster because super-glue cracks coatings and eats the lenses. 
-Optical Works Corporation

POLARIZED PROGRESSIVES
PROBLEM: Although I have an up-to-date edger with an LCD display, I have a difficult time identifying the marking and the location of the optical center and cross on my polarized progressives jobs. Sending them out all the time is getting expensive. Any suggestions for keeping those jobs in-house?
SOLUTION: Due to the darkness of the lens, it is indeed a bit more difficult to see the markings. You have to over-compensate by marking the optical center with a heavier cross than usual, using a very dark black marker.

Also, each manufacturer puts a set of arrows on the ends of the 180-degree line-both on the right and left sides. By using these lines as a guide, you'll ensure that your stay on center and keep the lens in the correct position.

-Bill Galindo, president, ODI/Topcon

RIMLESS SHORTCUTS
PROBLEM: We do a lot of rimless jobs, including rimless sunwear. In order to save time, can we scan a similarly shaped full frame lens instead of always using the demo lens?
SOLUTION: When you're edging a rimless style, whether it's sunwear or ophthalmic, don't try to cut corners like that. When the machine traces a full frame, the stylus raises and lowers in 3-D measurement, learning the linear value and curvature of the frame to get the circumference.

But the sizing will be off if you use that method for a rimless frame. It's worth the couple of seconds it takes to mount the demo lens so that it will be traced properly using the dowel.

-Frank Balestra, director of technical services, Santinelli International

PEELING COATINGS
PROBLEM: Coatings, particularly hard coatings, crack and peel. What can be done to eliminate this serious problem?
SOLUTION: Excessive clamping pressure and inflexible blocks cause the tendency for cracking and peeling. Making modifications to pressure settings on your edger is the solution, and the ability to do so will depend on the actual machine.

Thankfully, newer edgers are fitted with regulated clamping pressures and flexible blocks and virtually eliminate the guesswork in determining the right amount of pressure needed.

Older models have predetermined and tighter clamping pressure; therefore, adjustments must be made to the lens surface. By using a blocking tape on the front surface of the lens, you will create a layer of cushion between the surface coating and block, further reducing the tendency for cracking and peeling caused by excessive clamping pressure and inflexible blocks.

-Joe DeLapp, president, Briot, Inc.EB

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