question for lab managers....

[humbleABOCtx]

sorry, it's gotta be said.....Poly sux, way too many headaches ,splitting/cracking/starring @ drill holes
i only sell it to pt's already wearing it or upgrade to HIP...
if we complain enough and reduction is volume is noted maybe mfg will improve it's weak points.

[humbleABOCtx]

added note
just... remembering way back to my lab days not just acetone was a no-no but so was any neutralizer even poly neutralzier.
we had banned it from using it to remove pal markings and minimized stress crackes...
other reasonable explainaition (process of elimination....)
could be a dull blade..
chuck pressure incorrect
regardless of the last decadle problems at the lab level; As ya'll were talking earlier, I really believe they've changed the batter-formula

[gene_bautz]

do you use water when when the grinding is on finishing mode? maybe you grind the lens without water all through, you should use water when it is in the finishing mode. and never use acetone.

[Jan Post]

I just read about problems with polycarbonate and wanted to share it to all. http://www.devicelink.com/mpb/archive/98/05/001.html

[Jan Post]

The following technical article regarding plastics that crack and craze includes polycarbonate. Follow the link for factual eye opener , the article provides good resorces at the end of the article http://www.devicelink.com/mpb/archive/98/05/001.html

[Chris Ryser]

The following technical article regarding plastics that crack and craze includes polycarbonate. Follow the link for factual eye opener , the article provides good resorces at the end of the article http://www.devicelink.com/mpb/archive/98/05/001.html

This article is fine and dandy.............but there are ways and products to protect Poly from all these problems.

[HarryChiling]

Try Optochemicals drill seal, you can use it on edges and on drill holes. Our office started to use it for all rimless a year ago and never looked back, matter of fact I dropped and broke the bottle a week ago so Chris can you send me my order I have some drill's waiting.

[Jan Post]

Chris Ryder, I believe much of the problem so far hasent been solved. I previously worked in a surfacing labratory surfacing polycarbonate at Lenscrafters and the standard procedure in processing semifinished blanks, ie progressives, flat top bifocals and single vision polycarbonates was and is, cleaning the lens with isopropal alchohol after it comes off the second fining and prior to going into the coating machines. This step is prior to being sealed is washing the lens with isopropanol alchohol. I always wondered why the company did so many free redos due to cracking and crazing and no one ever gave adequate explaination for the defects. Its the companys problem now. The problems I see is other outside processing labs do the same proceedure while processing lenses sent to independents

[Jan Post]

Harry Chilling,

Thats great that you seal the drill holes after drilling but if the lens was previously surfaced and most are surfaced to get the proper thickness, it is most likely that the lens was washed with isopropal alchohol prior to you ever getting the lens and once the lens is washed with it, the matrix of the lens is now contaminated with the chemical. We arent talking about wetting a coated lens with alchohol we are talking about a virgin lens that has just had its back surface ground on a generator, fined and polished and then cleaned with isopropanol. It is this step that I believe which can be a flaw in the chain of production which may be universally a problem thoughout the industry. You never know if the problem is due to the lab that sent it to you which processed the lenses.

[HarryChiling]

Harry Chilling,

Thats great that you seal the drill holes after drilling but if the lens was previously surfaced and most are surfaced to get the proper thickness, it is most likely that the lens was washed with isopropal alchohol prior to you ever getting the lens and once the lens is washed with it, the matrix of the lens is now contaminated with the chemical. We arent talking about wetting a coated lens with alchohol we are talking about a virgin lens that has just had its back surface ground on a generator, fined and polished and then cleaned with isopropanol. It is this step that I believe which can be a flaw in the chain of production which may be universally a problem thoughout the industry. You never know if the problem is due to the lab that sent it to you which processed the lenses.

I know what your saying iso can crack a lens, but it's also highly volatile so when the lenses are heated before the coating process alcohol will evaporate. Now if the lens is beig cleaned after the fact with iso then there's an issue, not to mention that every eyeglass cleaner I have seen has some amount of iso in it. That's where sealing the edges and the drill holes makes a difference.

Also the process of coating the back side is a chemical reaction, the alcohol may act to roughin the lens surface up to allow for better adhesion. If we want a material that is more inert than CR39 will do the trick.

If you still think that poly is a problem due to processing just switch to hi-n or trivex if your a safety nut. Too many options available nowadays it's getting harder and harder just to keep up with the various options. I do think at some point int he process they messed with teh recipe for poly but where and how is a mystery to me.

[Jan Post]

In addition to a inherent contamination of the lens, the sales floor often clean the lens with alchohol or alchohol based cleaners, if the lens was a stock lens or surfaced lens, and finished, the edges are exposed matrix. If these edges werent seal treated as Harry Chilling does, the problem persists indefinetly. The question therefore is how many optical establishements actually use this edge and hole treatment which cant account for cracking and crazing. Lets hope a solution is on the rise after so many years of customers coming back in after a purchase anywhere from one week to one year later with edge cracking polys. Since the consumer is always right and you cant prevent them from using alcholol based lens cleaning products, it may be the responsability of the optical firm and the manufactures to seal the lenses and also the need for the sealer manufactureer to guarantee its product for a minimum of one year while the lenses are still under warranty.

[Jan Post]

Harry, the lenses arent heated before the coating process they are drenched cleaned in alcholol as the go into the coating machine with a swabbing pad, no heating of the lens occurs.

[HarryChiling]

Tell your patient's to use Dawn (without the antibacterial or the lemon scented stuff) and bounty paper towels. Study attached.

Dawn can also do the dishes. :D Jan it's obvious your good at what you do these little things help the creme rise to the top, it seperates us into different categories of optician.

[HarryChiling]

Harry, the lenses arent heated before the coating process they are drenched cleaned in alcholol as the go into the coating machine with a swabbing pad, no heating of the lens occurs.

This is the type of equipment I have seen in large labs (document attahced), you'll notice that they use heated air to dry the lenses, most don't use iso in the cleaning process but some do. The idea is you want to get any water off the lenses before coating and since alcohol evaporates before water it is less of an issue than you might think. Of course I may be wrong here the large labs could have the same rinky dinky UV coaters that a lenscrafters has. You'll be amazed at how dumbed down the LC model is comapred to a highly sophisticated opthalmic lab.

[Jan Post]

I just need to add that it is not Lenscrafters but Coburn procedures. And we know that Gerber Coburn is a leading Lens Processing Equiptment Player in the Industry

[Jan Post]

I looked up the newest Gerber Coburn procedures and it seems they are using ionized water, no mention of isopropanol. I imagine the company is addressing the issue with its newest equiptment. I previously worked for seven years in the surfacing lab and with the equiptment used, the alchohol was used. I visited my prior store lab and the two lab managers were there and they still were using isopropal to clean them just as I did for seven years. This makes me wonder if any firm with such prior equiptment is still doing the same status quo.

[jherman]

silicon or aluminum, aluminum can have odd affect on some of the mid to hi indexes, fissure being one.

[HarryChiling]

How are going to get the layout markings off with Dawn???

BTW, I use denatured alcohol from the paint stripper section. Is that wrong? Stressful on AR?

MarcE, denatured works well it's not isopropyl alcohol. I like everclear personally it's straight from the liquor store, grain exactly like denatured except they don't add poisons. Plus every now and again with those rowdy patients you can take a swig and your day gets better. ;)

[HarryChiling]

I just need to add that it is not Lenscrafters but Coburn procedures. And we know that Gerber Coburn is a leading Lens Processing Equiptment Player in the Industry

No WE don't, I use gerber equipment in the lab I am in now and it's made more for the button pusher. Alcohol is still being used by many in small outfits but the larger labs don't use it and don't have many of the issues your talking about. That's why it's good to constantly keep up with new infromation.

[chip anderson]

Permabrite, formerly Obrite cleaner. The only spray cleaner that I am aware of that can be used on all spectacle lenses and all rigid contact lenses. Contains no alcohol, no acetone. Actually I think it contains mostly EDTA.
Have used it for glasses and rigid lenses for 50 years, my predicessor was using it before that.


Chip

[Chris Ryser]

Since the consumer is always right and you cant prevent them from using alcholol based lens cleaning products, it may be the responsability of the optical firm and the manufactures to seal the lenses and also the need for the sealer manufactureer to guarantee its product for a minimum of one year while the lenses are still under warranty.

The sealing of the surfaces is done with the hardcoat, but wen cut into shape the edge stays un protected.
That is the place were all the goodies attacking poly can assemlble and do their work. Your lab people most probably are not even aware that this step can be done. It is also additional material and work to do.

I dont think the sealer manufacturer should carry the warranty, as he has no control that this extra step has been applied.

[HarryChiling]

I dont think the sealer manufacturer should carry the warranty, as he has no control that this extra step has been applied.

I agree with you here Chris, I'd rather you not carry any warranty and me purchase and use your product affordably for all my patients. Sure it's an extra step, but one that most places don't use and one that definately makes my rimless hands down better quality then the rest.

[Jan Post]

Hey, me again. Was wondering your thoughts regarding polycarbonate warranty? If firms are giving scratch warranty for a year, who ends up eating the cost for lens cracking also? Since it seem the culprit seems to be attributed to alcohol based cleaning, do we contiunue to absorb the cost of redos and refunds for lenses the customer is assuming is the fault of the firm they purchased from. Since we can not blame the customer for inappropriate cleaning and the fact that lens cleaners are marketed as lens and a/r cleaner and contain ingredients not benficial to polycarbonate how do you confront this issue? Who absorbs the cost of selling polys? Maybe we need to switch to a better material even given the postive benefits of poly.

[HarryChiling]

Hey, me again. Was wondering your thoughts regarding polycarbonate warranty? If firms are giving scratch warranty for a year, who ends up eating the cost for lens cracking also? Since it seem the culprit seems to be attributed to alcohol based cleaning, do we contiunue to absorb the cost of redos and refunds for lenses the customer is assuming is the fault of the firm they purchased from. Since we can not blame the customer for inappropriate cleaning and the fact that lens cleaners are marketed as lens and a/r cleaner and contain ingredients not benficial to polycarbonate how do you confront this issue? Who absorbs the cost of selling polys? Maybe we need to switch to a better material even given the postive benefits of poly.

Our office does, but that's why they call it the "poor mans hi-n".:D

[pezfaerie]

We have seen a mass of poly lenses, no matter the vendor, cracking/splitting like mad. We have tried adjusting just about everything in the edging process to no avail!
You're not alone:hammer: