I don't want to say never, but we almost never have poly lenses crack on rimless even after years of use. the single most important factor is the sharpness of the blade, cutting wheel, or drill bit.
I don't want to say never, but we almost never have poly lenses crack on rimless even after years of use. the single most important factor is the sharpness of the blade, cutting wheel, or drill bit.
Seal Polycarbonate Lens Edges For Protection...........
Originally Posted by Happylady
You should not use anything that is not compatible with the structure of Polycarbonate if you have any un-protected areas on the lens. And here follows a detailed explanation:
1)............. All poly lenses are dip coated with a protective hard coat, by the manufacturer after they come out of the injection mold. That goes for blanks as well as finished uncut lenses. When dip coating even the the edge has a protective layer.
2) ..............when the lab surfaces a lens blank on the minus side, it re coats the minus side before it leaves the lab. If the lab would use any chemically non compatible agents for cleaning and so forth, it would start a destructive chain reaction that would craze the lens within about 12 hours.
3)..............When the optician receives the lens in good condition it assumable that has been no damage done by the lab, therefore you have to use the standard caution on the lens which after you work it, has several non protected areas:
a) Drill holes
b) The whole edge of the lens for 360 degrees
4).............If you do not use any alcohols, neither as lens cleaners or marking removers you should be fairly safe. Use only marking removers that are safe for poly and don't give customer a lens cleaner that contain any trace of methanol which most of them do if they don't state that they are made from surfactants only.
5) ...........The edge of the finished lens is now your most endangered area on the whole glasses. It is the largest non coated area on the lens and is susceptible to chemical attacks either by fumes or liquid chemicals. ( a women doing her fingernails, a guy using paint thinner, gasoline fumes and thousands more)
6)............We have developed a product a few years ago that is made from several silicon copolymers mixed together and cures by humidity. We have just discovered, that, even if it has been used for other applications, when applied to un-protected polycarbonate edges, it gives them a total seal aginst against most common chemical attacks. One drop can coat up to 4 pairs of lens edges, is totally invisible and will last for years.
A lot of big, even corporative and small labs and retailers today, are users of our "DrillSeal" to protect poly drill holes from crazing for the last 2 years, well promoted by "Vision Ease".
And I believe that "TotalSeal" will become anther success as it actually solves the other big problem of the "open wound" on plycarbonate lenses.
Had the same problem in my lab, all poly lenses cracked dramatically at edges shortly (hours to days) after dispensing. My manager asked me again to make sure we weren't using isopropanol on the lenses (she'd heard that was the problem when this happened at our lab the last time) we were using a marking remover pen and regular lens cleaner. We switched to 90% isopropanol and threw out the marking remover pens.
I'd bet that's their problem. Especially if it is happening with poly only.
Yes, switching to trivex solves the problem and upgrades optics significantly. However, that doesn't explain why one account has this problem continuously with poly lenses.
All it takes is cheap lens cleaners .....................
...............because the lab is careful with solvents on poly, the one account is the one that is not. All it takes is cheap lens cleaners not specifically made with surfactants only. But they do cost a bit more.
I have one particular patient that is in a Varilux Ellipse in Poly.. with Alize coating, and her lenses have developed stress like feathering and cracks on 3 occasions. This last time, the lenses were sitting in our drawer for 6 weeks, so we know it isn't just the patient.
It is a semi-rimless guess frame, the top isn't a metal liner, and the to me.. the former lab rat turned retail. .looks like it is with the groove itself. Running my nail in the groove feels rough, dry, and ugly.
Lab wonders if there is a problem with the coating, wanted to see the lenses w/o her taking them. But since her old pair lost a lens, we ended up dispensing the glasses back to her.
Lab thinks it might be a frame issue. Don't really see what would cause this since it isn't an extreme angular shape..
"Some believe in destiny, and some believe in fate. But I believe that happiness is something we create."-Something More by Sugarland
A serious question- A lot of spray lens cleaners have alcohol in them. Should they not be used on drill mounts and/or grooved rimless poly jobs? What about All Off?
...............this question has already been anwered on this thread and many others. If you seal the unprotected areas on a lens, it becomes resistant to most chemicals, if you don't, you will have crazed Poly lenses and blame anything and anybody under the sun form Canada to Florida.
As for the "ALL OFF" ask your supplier. If it does attack Poly there are others on the market that don't.
I don't know if the labs seal the drill holes on poly lenses. I'm sure they don't do anything special to the edges of grooved lenses. I have grooved poly lenses and have had no problems with them using lens cleaner.
Vision Ease recommends "Drill Seal"........................
Many of the small labs and a good number of the corporative big labs, among them, Walman Optical is one of the largest users, of the by Vision Ease recommended "Drill Seal". Just ask your own lab if the do seal their drilled holes, and you will know.
Obviously the increasing number of use of that product must have reduced cracking from the drill holes on rimless drill holes over the last 2-3 years. By doing so the lab reduces free re-does under warranty and the opticians having more happy customers.
An unprotected lens edge between a drill hole frame and a grooved lens one, sees and feels no difference when exposed to damaging chemical products or fumes. It will however do so when protected, and will not get damaged.
Hi Chris
I am in the UK anybody sell drill seal over here?
Thanks
Alan
Oh lord, I didn't realize until just now I +1'd an 8-year old post. Time for some coffee...
Only just posted a couple of hours ago!
Locktite will crack poly. I found out that the hard way.
Caroline, L.O.
If you suffer from severe nonlinear waterfowl issues, you don't have your ducks in a row.
Yes Alan,..............Inland UK has it in stock for the last few years.
Yes, He is totally right, I'm agree with that. I only suggest these things.
Very rare to find methynol, since it is so poisonous.
The 'denaturing' is a bitter flavor. So unpleasant that you don't want to drink it. Added to Ethynol.
I just checked and isopropynol doesn't have a bitter taste. Probably won't get you drunk either. But I would advise against injesting it anyway.
me too
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