Page 2 of 3 FirstFirst 123 LastLast
Results 26 to 50 of 52

Thread: Poly cracking... What's up?

  1. #26
    Master OptiBoarder mike.elmes's Avatar
    Join Date
    Jan 2006
    Location
    edmonton,alberta, Canada
    Occupation
    Dispensing Optician
    Posts
    533
    How about a test using the same two lenses and a jar of acetone.:p

  2. #27
    Master OptiBoarder OptiBoard Gold Supporter DragonLensmanWV's Avatar
    Join Date
    Oct 2006
    Location
    The Greatest Nation
    Occupation
    Optical Retail
    Posts
    7,645
    Quote Originally Posted by mike.elmes View Post
    How about a test using the same two lenses and a jar of acetone.:p
    That would be pretty short, huh?:D
    DragonlensmanWV N.A.O.L.
    "There is nothing patriotic about hating your government or pretending you can hate your government but love your country."

  3. #28
    Master OptiBoarder Darryl Meister's Avatar
    Join Date
    May 2000
    Location
    Kansas City, Kansas, United States
    Occupation
    Lens Manufacturer
    Posts
    3,700
    Within the past year or so I have seen repeated pairs of specs with poly lenses cracking. We've dispensed poly for years, however, this past year a crazy amount of lenses have been cracked.
    It is usually due either to the release of stress in the polycarbonate material after surfacing/edging/drilling or to chemical attack.
    Darryl J. Meister, ABOM

  4. #29
    OptiBoard Apprentice
    Join Date
    Aug 2009
    Location
    Texas
    Occupation
    Optical Laboratory Technician
    Posts
    10
    I work at a chain of sorts. And we've had the same problem within this past 6 months. We've been very careful to not tighten the screws to tight. As well as cooling the frame immediately after popping a lens into a zyl frame. A lot of mishandling goes on with the retail clerks but that's all that seems to be causing the problems on my end.

  5. #30
    OptiBoard Apprentice Nikki McGee's Avatar
    Join Date
    Oct 2008
    Location
    Colorado
    Occupation
    Dispensing Optician
    Posts
    35
    The only time I've had repeated problems with poly cracking it was coming from the lens marking removal pens. I switched brands and had no more trouble.
    ABOC

  6. #31
    One eye sees, the other feels. OptiBoard Gold Supporter
    Join Date
    Jul 2002
    Location
    Wauwatosa Wi
    Occupation
    Dispensing Optician
    Posts
    4,931
    Quote Originally Posted by Darryl Meister View Post
    It is usually due either to the release of stress in the polycarbonate material after surfacing/edging/drilling or to chemical attack.
    And the chemicals are all around us- acetone in fingernail polish remover, ammonia in glass cleaner, methacrylate-like substances in hair spray, and so on.

    Even with the use of first-rate labs, I've seen about 20% of my poly lenses crack over the lifespan of the glasses.

    I'll only use poly if I'm reasonably sure they'll be in a non-chemical environment and if there are no other materials available in the lens design that would be best for my client.
    Roberts Optical Ltd.
    Wauwatosa Wi.
    www.roberts-optical.com
    ~~~~~~~~~~~~~~~~~~
    Science is a way of trying not to fool yourself. - Richard P. Feynman

  7. #32
    Banned
    Join Date
    Jun 2000
    Location
    Only City in the World built over a Volcano
    Occupation
    Dispensing Optician
    Posts
    12,996

    We may have been down this road before but...

    Any body smart enough to find out and list all the chemicals that can or will attack Poly? Trivex? Various and Sundry Coatings?
    This would be a nice thing for us workin stiff opticians to know.

    Chip

  8. #33
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Redhot Jumper I am smart enough, and have posted

    Quote Originally Posted by chip anderson View Post

    Any body smart enough to find out and list all the chemicals that can or will attack Poly?


    Chip
    I am smart enough, and have posted this same before a few times over the years, but it does not seem to sink in................



    The following require caution:
    Cyclohexone
    Glycerine
    Sulphur Dioxide
    Diesel Oil
    HeatingFuel
    Turpentine
    Formic Acid
    Jet Fuel
    Gasoline
    Perchloric Acid-Conc.


    The following will attack polycarbonate:
    Acetone
    Caustic Soda
    Methyl Ethyl Keytone
    Acrylonitrile
    Chloroform
    Perchloroethylene
    AmmoniaDimethyl
    Formamide
    Styrene
    Amyl Acetate
    Hydrochloric Acid-Conc.
    Toluol
    Benzene
    Hydroflouric Acid-Conc.
    Sulphuric Acid-Conc.
    BromineIodine
    Xylene
    Butyl Acetate
    Methanol


    Drill Holes.............



    Allow for proper expansion in all drill holes. Do not drill within 1 1/2" from the edge of the sheet.


    When fastening screws, do not tighten below the surface of the panel.


    Last edited by Chris Ryser; 08-12-2009 at 02:43 AM.
    Chris Ryser
    ________________________________________
    DLO. NA.IC.I.T.PO

    http://optochemicals.com............................. http://arcoatings.com

  9. #34
    Banned
    Join Date
    Jun 2000
    Location
    Only City in the World built over a Volcano
    Occupation
    Dispensing Optician
    Posts
    12,996
    Thanks Chris:

    I am a little confused with the drill hole instructions. I would understand this if we were drilling large diameter holes in 4 & 8' sheets, but don't understand not drilling withing 1 1/2" of sheet.

    Now how are you on chemicals and other things that Anti Reflective Coatings don't get along with well?

    In fact as long as we gittin smarter what are the causes of Scratch Coat failure?


    Chip
    Last edited by chip anderson; 08-12-2009 at 06:53 AM. Reason: ARC comment & SRC Comment

  10. #35
    Master OptiBoarder OptiBoard Gold Supporter DragonLensmanWV's Avatar
    Join Date
    Oct 2006
    Location
    The Greatest Nation
    Occupation
    Optical Retail
    Posts
    7,645
    Quote Originally Posted by DragonLensmanWV View Post
    Just for giggles, when I came back from vacation on Monday, I edged a poly lens and a trivex lens, inscribed a P and a T on them with a diamond scriber and put them in a jar and filled it with the 99% isopropyl I use to clean the lenses before coating.

    So far, no damage to either one. Let's see how long it takes.
    OK, been a week and a half and I got the lenses out today. The poly lens has it's coating starting to erode around the periphery of the bevel and several spots in the coating elsewhere and the edge has become slightly glazed.
    The Trivex lens only has the few spots formed in the lens coating without any other effects.
    DragonlensmanWV N.A.O.L.
    "There is nothing patriotic about hating your government or pretending you can hate your government but love your country."

  11. #36
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Redhot Jumper

    Quote Originally Posted by DragonLensmanWV View Post
    The poly lens has it's coating starting to erode around the periphery of the bevel and several spots in the coating elsewhere and the edge has become slightly glazed.
    The Trivex lens only has the few spots formed in the lens coating without any other effects.
    As you put the lenses into ISP try again into Methanol or Acetone to see a fast response.
    Chris Ryser
    ________________________________________
    DLO. NA.IC.I.T.PO

    http://optochemicals.com............................. http://arcoatings.com

  12. #37
    Master OptiBoarder Darryl Meister's Avatar
    Join Date
    May 2000
    Location
    Kansas City, Kansas, United States
    Occupation
    Lens Manufacturer
    Posts
    3,700
    Quote Originally Posted by chip anderson View Post
    I would understand this if we were drilling large diameter holes in 4 & 8' sheets, but don't understand not drilling withing 1 1/2" of sheet
    This really applies mainly to materials with non-negligible coefficients of thermal expansion and contraction, like metals.
    Darryl J. Meister, ABOM

  13. #38
    Master OptiBoarder snowmonster's Avatar
    Join Date
    Jul 2005
    Location
    Somewhere
    Occupation
    Optometrist
    Posts
    1,195
    Quote Originally Posted by DragonLensmanWV View Post
    OK, been a week and a half and I got the lenses out today. The poly lens has it's coating starting to erode around the periphery of the bevel and several spots in the coating elsewhere and the edge has become slightly glazed.
    The Trivex lens only has the few spots formed in the lens coating without any other effects.
    You need to put those lenses into the frame and the polycarb will likely start cracking within 2-3 days. You're not inducing any stress in the lens by soaking it in IPA, you're just stripping the coatings.

    We went through a brief period where we were cleaning edged lenses with 70% IPA and noticed a huge number of cracks in the lenses as described by Jamie Brady. We stopped using the IPA and used regular cleaner (without any IPA content) and everything went back to normal instantly.
    -Steve

  14. #39
    Banned
    Join Date
    Jun 2000
    Location
    Only City in the World built over a Volcano
    Occupation
    Dispensing Optician
    Posts
    12,996
    Please, don't add any new abreviations to the industry, spell out isopropyl alcohol, so us dummies won't have think so hard to know what your are talking about.

    Chip

  15. #40
    Master OptiBoarder snowmonster's Avatar
    Join Date
    Jul 2005
    Location
    Somewhere
    Occupation
    Optometrist
    Posts
    1,195
    I didn't think it was new.
    -Steve

  16. #41
    Master OptiBoarder rinselberg's Avatar
    Join Date
    Jan 2004
    Location
    Sunnyvale, CA 94086
    Occupation
    Other Eyecare-Related Field
    Posts
    2,301
    Quote Originally Posted by snowmonster View Post
    You need to put those lenses into the frame and the polycarb will likely start cracking within 2-3 days. You're not inducing any stress in the lens by soaking it in IPA, you're just stripping the coatings.

    We went through a brief period where we were cleaning edged lenses with 70% IPA and noticed a huge number of cracks in the lenses as described by Jamie Brady. We stopped using the IPA and used regular cleaner (without any IPA content) and everything went back to normal instantly.
    Don't use "IPA" to abbreviate isopropyl alcohol. Fezz will think you are talking about India Pale Ale.

  17. #42
    Master OptiBoarder
    Join Date
    Oct 2004
    Location
    Down in a hole!
    Occupation
    Dispensing Optician
    Posts
    13,045

    Now I am thirsty!!!

    Quote Originally Posted by rinselberg View Post
    Fezz will think you are talking about India Pale Ale.


    :cheers::cheers::cheers::cheers::cheers::cheers:

  18. #43
    OptiBoard Novice
    Join Date
    Aug 2009
    Location
    Manchester, New hampshire
    Occupation
    Dispensing Optician
    Posts
    3

    poly cracking

    I've been complaining about poly cracking for years. Some cracks show up in the outer edge but occasionally I have seen them in the dead center. I believe eccessive heat during edging might be the problem. I did have the oppurtunity to ask a poly manufacturer's rep about the problem and the answer was awesome. he asked back "What cracks?"
    That answer made my poly usage drop to 4%. I prefer most any other material.

  19. #44
    OptiGeek Wes's Avatar
    Join Date
    Nov 2007
    Location
    Earth
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    3,177

    That's the first thing that crossed my mind.

    Quote Originally Posted by rinselberg View Post
    Don't use "IPA" to abbreviate isopropyl alcohol. Fezz will think you are talking about India Pale Ale.
    :cheers:Made me want to take a trip to the Flying Saucer.:cheers:

  20. #45
    OptiBoard Apprentice
    Join Date
    Apr 2009
    Location
    Plymouth
    Occupation
    Optometrist
    Posts
    28

    Easy fix for cracking Poly

    He is a simple fix for your problem with Polycarbonate cracking, Don't use it. Polycarbonate is a terrible material. Use plastic, trivex or index materials and let your patients finally see. Leave Polycarbonate to the box stores.

  21. #46
    OptiBoard Apprentice
    Join Date
    Aug 2009
    Location
    Illinois
    Occupation
    Optical Laboratory Technician
    Posts
    12

    Arrow I believe

    at least to my satisfaction, and that of my officemates, that the problem is solvent related.
    I've seen the cracking lens problem before this, but never in these numbers. 20+ years ago I was a dispenser in a busy superstore and got sick to death of the "They can send a man to the moon, but they can't keep the screws in my glasses...." One day I happened on Loktite and passed a bottle on to a couple of my fellow dispensers, and the problem went from 60 to almost zero inside a couple months.
    Some years later, after seeing cracks appearing on lenses at the screw barrels, one of the bright guys I shared the bottles with contacted the Loktite company and they said that there was an ingredient that may react with polycarbonate. I changed to a poly safe threadlock from Vigor-now labeled not safe for poly, and the problem all but went away. When I'd see it happen in later years occuring away from the screw barrels, I always suspected a cleaning solvent, probably something that accelerated evaporation, or perhaps a caustic work environment for the individual presenting his cracked lenses to me. The problem was rare, but seemed to happen to the same few people in an office, time after time.
    Last fall, we got a good deal on some lens cleaner in printed bottles we give to our customers at dispense. It took a month or two, but these cracking lens returns became a daily occurence. It only happened on polycarbonate lenses. I let the staff know my strong hunch. They all had had the experience of wiping the progressive marks off a poly lens and had it split under no other stress, so it seemed plausible enough for one of them to say "let's test it!" To the man (person, every patient returning these lenses was asked "how are you cleaning them?" and responded "with that lens cleaner you gave me." I grabbed a frame off the board, cut some lenses and left them at the front desk to be cleaned twice a day. It only took a day for one lens to fail. Another test, another failure. Late March we pulled the cleaner off the shelves and told patients to just use soap and water. The cleaner was manufactured in China. The company has it made in a couple other countries also, but ours was from China. Another theory of mine was Chinese metallurgy or paint additives, but I've seen enough occurences in plastic frames to make me doubt that.
    Anyway, it's late August and cracked lenses are just about a thing of the past. Furthermore, if we do see one come in from our office, the date of the original eyeglass sale ALWAYS falls between the time we took delivery and suspended our delivery to patients. I have no choice but to believe.

  22. #47
    Banned
    Join Date
    Jun 2000
    Location
    Only City in the World built over a Volcano
    Occupation
    Dispensing Optician
    Posts
    12,996

    What we be 'fraid of?

    How come we can mention Loctite by name in causing Poly cracking but won't name the brand on lens cleaners known to cause problems?

    Chip

  23. #48
    Bad address email on file
    Join Date
    Dec 2007
    Location
    Higher than 3500FT ASL
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    1,211
    Quote Originally Posted by carnzo View Post
    He is a simple fix for your problem with Polycarbonate cracking, Don't use it. Polycarbonate is a terrible material. Use plastic, trivex or index materials and let your patients finally see. Leave Polycarbonate to the box stores.
    Poly is cheap and crap period. I agree that Trivex is an excellent alternative to provide and your patients/customers will love you for it!

    Let's put ourselves in the customer's shoes...it's a huge inconvenience!

  24. #49
    OptiBoard Apprentice
    Join Date
    Aug 2009
    Location
    Illinois
    Occupation
    Optical Laboratory Technician
    Posts
    12

    Definitive answer here, if a little long.

    Duplicate post deleted.
    Last edited by jrh291; 08-27-2009 at 01:25 PM. Reason: Duplicate

  25. #50
    Manuf. Lens Surface Treatments
    Join Date
    Aug 2002
    Location
    in Naples FL for the Winter months
    Occupation
    Other Optical Manufacturer or Vendor
    Posts
    23,240

    Blue Jumper when greedy you get what you pay for.......................

    Quote Originally Posted by chip anderson View Post
    How come we can mention Loctite by name in causing Poly cracking but won't name the brand on lens cleaners known to cause problems?
    Chip

    When somebody wants to sell lens cleaners to optical retailers is not a matter what it contains, it has to clean and it has to be cheap.

    It actually is a fight for prices, who is 1/2 cent cheaper than the competition, and it has been like that forever. Chains or independent Opticians are all the same when it comes to lens cleaners. It should cost just about near to nothing and nobody cares what is in the formula. The most common formula is 20% ISP and 80% water. That is cheap to make for anybody and can be sold at any price you can get away with and that was what happened in above post.

    Last fall, we got a good deal on some lens cleaner in printed bottles we give to our customers at dispense.
    Nobody cares what such lens cleaners can do as long as it cost's barely nothing so that we can give them to customers as advertising, instead of selling a good product that will clean and protect.

    The same goes also for eyeglass cases they have to be the absolute cheapest because they have to given away. I feel sorry for sales reps that sell those two items as they are under pressure to nearly give these items away for nearly nothing. So don't wonder why when greedy you get what you pay for.


    ..........................:finger:.........................
    Chris Ryser
    ________________________________________
    DLO. NA.IC.I.T.PO

    http://optochemicals.com............................. http://arcoatings.com

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Interesting study on optical lenses cracking.............
    By Chris Ryser in forum General Optics and Eyecare Discussion Forum
    Replies: 0
    Last Post: 01-07-2009, 11:10 AM
  2. Kodak Isp lens cracking in drill mounts
    By evville in forum General Optics and Eyecare Discussion Forum
    Replies: 16
    Last Post: 10-27-2008, 09:37 AM
  3. Cracking poly...
    By AutumN in forum General Optics and Eyecare Discussion Forum
    Replies: 21
    Last Post: 05-15-2007, 09:03 PM
  4. Polycarbonate cracking in zyl frames (follow-up)
    By snowmonster in forum General Optics and Eyecare Discussion Forum
    Replies: 1
    Last Post: 02-09-2007, 06:56 AM
  5. Environmental Stress Cracking in Rimless Lenses?
    By zippiz in forum General Optics and Eyecare Discussion Forum
    Replies: 58
    Last Post: 10-12-2006, 08:15 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
OptiBoard is proudly sponsored by:
Younger Optics and Vision Equipment