I just received information concerning the use of polycarbonate lenses and zyl frames indicating that the two are incompatilble. I'm not talking about any material other than hand-crafted (the good stuff) zyl. There are reports of issues with frame colors leeching into the lenses and frames becoming brittle in a short amount of time.
Any input?
The zyl I'm using (axel, pro design etc...) must not be any good, because I've never had an issue.
Classic materials.........................
If you use frames made with classic materials such as cellulose acetate which has been the standard frame material, there should be no problem of anything leaching as the colors are contained within the material and properly cured.Originally Posted by Judy Canty
However some injected materials might have been surface colored with solvent containing pigments, there could maybe be a problem.
However there are products available with which you can easily coat the polycarbonate bevel after edging and before inserting into the frame and which will give a solid firewall between lens and frame.
Chris: I have also been told by a number of people in the business that you can not put poly lenses in Acetate (Zyl) frames. If the problem is said to be the frame color bleeding into the lens, I can not imagine this being possible since poly itself will not tint.
If could be a reaction from years ago with a backside coating and the Acetate.
I have never had a problem with an ICE-TECH zyl frame with a poly lens.
Chris I'll look for your thoughts.
There can be a chemical reaction between acetate and poly. Years ago I was told what the specific chemical reaction was, but have forgotten. I think a very tight fitting lens is required to enable the reaction (or transfer of chemicals) and hence it is not common. The somewhat more common case and how I first became aware of the issue is with tight fitting side shields on acetate temples of safety frames.
Here is a list....................
Maybe this list can shed some light on the issue to start with:
Chemical Compatibility of Membranes
MCE: Mixed Cellulose Ester (Nitrocellulose)
CA: Cellulose Acetate
PCTE: Polycarbonate
PTFE: Teflon
CMF: Coated Cellulose Acetate l : Recommended
u : Limited resistance
X : Not recommended
-- : No data available
I wonder if this info was from a frame or lens rep? In 12 or so years, I've never seen this happen.
Polycarbonate and plastic frames.......................
Actually neither have I. This is the first time I heard it mention. During the 60s and 70s when I was a frame distributor and had a lab. Polycarbonate lenses were just about introduced by Gentex. Even then there was never a problem I heard of.
Colors from cellulose acetate will never leach anyhwere as the whole material is properly cured and the plates are aged for a while before they are sold to frame manufacturers.
Cellulose acetate is colorfast..........................
Fiber
Cellulose acetate or acetate rayon fiber (1924) is one of the earliest synthetic fibers and is based on cotton or tree pulp cellulose ("biopolymers"). These "cellulosic fibers" have passed their peak as cheap petro-based fibers (nylon and polyester) and have displaced regenerated pulp fibers.
It was invented by two Swiss brothers, Doctors Camille and Henri Dreyfus, who originally began chemical research in a shed behind their father's house in Basel, Switzerland. In 1905, Camille and Henri developed a commercial process to manufacture cellulose acetate. The Dreyfus brothers initially focused on cellulose acetate film, which was then widely used in celluloid plastics and film. By 1913, Camille and Henri's studies and experiments had produced excellent laboratory samples of continuous filament acetate yarn. In 1924, the first commercial acetate filament was spun in the United States and trademarked as Celanese [1] .
See the whole article at : http://en.wikipedia.org/wiki/Cellulose_acetate
[edit] Fiber Properties
Acetate is a very valuable manufactured fiber that is low in cost and has good draping qualities. Properties of acetate have promoted it as the “beauty fiber”[1]. Acetate is used in fabrics such as satins, brocades, and taffetas to accentuate luster, body, drape and beauty.
- Hand: soft, smooth, dry, crisp, resilient
- Comfort: breathes, wicks, dries quickly, no static cling
- Drape: linings move with the body linings conform to the garment
- Color: deep brilliant shades with atmospheric dyeing meet colorfastness requirements
- Luster: light reflection creates a signature appearance
Performance: colorfast to perspiration staining, colorfast to dry cleaning, air and vapor permeable
- Tenacity: weak fiber with breaking tenacity of 1.2 to 1.4 g/d; rapidly loses strength when wet; must be dry cleaned
- Environmentally friendly: made from wood pulp of reforested trees
- Abrasion: poor resistance
- Heat retention: poor thermal retention; no allergenic potential (hypoallergenic)
- Dyeability: (two methods) cross-dying method where yarns of one fiber and those of another fiber are woven into a fabric in a desired pattern; solution-dying method provides excellent color fastness under the effects of sunlight, perspiration, air contaminants and washing [1,2]
Polycarb tints great, on the edges of the lens where the frame is in contact with it. The hard coatings keep it from tinting well elsewhere.
2 months ago, I would have said this is a bunch of crap. But we've have three instances where we've used the AO Rugged Fashionwear polycarb stock lenses in zyl frames and the lenses cracked before they ever left the office. One of these was a same-day job just yesterday. We recut using the same exact edger settings and the lens was not cut too large - it snapped into the frame fairly easily.
Chris - which product are you talking about to help prevent this?
Thank you!
-Steve
I don't know who told you this but perhaps they were trying to sell you something? Never, ever has this been a problem.
the lenses cracked before they ever left the office..............
See at : http://optochemicals.com/products/info_frame_protec.htm
The issue is rare and the chemical interaction and/or transfer between frame and lens does take place through the edges of the beveled lens. A tight fit increases the risk. The case with side shields is also with tight fits and poly shields that do not have the protective coating that lenses have.
The key points - it is rare but it does happen.
Maybe I'm crazy, but wouldn't a simple dip hard coat be enough to seal the edges of the lens and prevent the frame-lens interactions?
Or would that cause problems with the already existing hard coat on the front/back of the polycarb lenses?
-Steve
Multiple problems.................................
The front has a factory applied dip coat that is a polysiloxane, and the back probably a uv cure hard coat that canj consist of a dozen different variations. You can not bond a Uv cure material to a siloxane coating so you have a gap where they join. This idea would not work.
Snowmonster said:I doubt that you would want to attempt to dip coat a cut lens. It probably will not turn out. Then the you have to AR process the cut lens.Maybe I'm crazy, but wouldn't a simple dip hard coat be enough to seal the edges of the lens and prevent the frame-lens interactions?
The cost would be prohibative in most cases since this is not the normal method of processing. Using a 1.60 lens without any risk would be more cost effective and easier to order.
What I'm thinking is taking your basic Gentex or AO polycarb lens, edge it, and then hard coat it in a random dip coat.
The Gentex or AO stock lens is already hard coated, so I'm thinking your dip coat would only adhere to the edge and not the front or the back of the lens. Of course, this would be useless for AR jobs.
I don't want the coating to stick to the front or back, just the edge. So if it doesn't adhere to the front or back, that's perfect.
Hey - that's post #200 for me. :)
-Steve
http://www.eyeglasses.com/eyeglass_frames.page
If zyl eyeglass frames reach a temperature over 160 degrees Fahrenheit, the plasticizers could rise to the surface of the frame
http://www.marchon.com/MarchonWeb200...phthalmic.html
The plasticizers don't "creep" to the surface if the correct amount of heat - not more than +160 degrees Fahrenheit - is applied, meaning that the end product is less brittle than it would otherwise be. But if the frame is left in a parked car on a particularly warm day, those plasticizers may well "creep" into the frame's surface, turning parts of the frame a milky white color. Body oils, perspiration, cosmetics and ultraviolet radiation can also adversely affect the material.
But we cold-insert all of our plastic frames and the lenses are fine when they go in. After they sit a while(and not inside of a really hot car), they have develop cracks.
-Steve
I remember having a problem ages ago with poly breaking frames not lenses. We would edge plus poly's into a line of Logo frames and they would look fine. An hour later the eyewire would be split in two front to back as if the V bevel cut right through it. We thought our shape/sizing was fine; however, if we looked at the lenses through a polariscope, you could see points where a great deal of pressure was being put on the lens.
Snowmonster said:Good idea but it won't work for a number of reasons. Who would do this dipping process?I don't want the coating to stick to the front or back, just the edge. So if it doesn't adhere to the front or back, that's perfect.
How are you going to make sure none of the dip coating sticks to the front and back?
Who is going to pay for this expensive special processing. You know the retailers in optical don't exactly have a reputation for: "I don't care what it costs I just want it that way".
First you can not place a polysiloxane dip coating over a UV coat without a primer in most cases. The poly lens would be hard coated on the back you suggest. Would this be done with a UV coating?
Just curious, do you personally have experience working with lens coating?
If so have you ever worked with dipped lens hard coatings?
Easy to apply sealer.
I told you in post further back that I have a sealer, easy to apply and it will work. Who wants to try it??????????????????????
See at : http://optochemicals.com/products/info_frame_protec.htm
Ok, so I was really wanting to do a quick and easy treatment to the lenses, not the frame. I would rather not mess with the frame if possible.
I was just thinking that something like the dip hard coats that Chris Ryser has, or something like the ones you can get from any lab would be an option. So therefore, my guy who edges lenses would then toss a pair of polycarb lenses into the dip hard coat and then rinse them off. A very quick and inexpensive process.
Who's to say such a dip coat would even stick to the front and back of the lens? Once a UV-cured hard coat is applied, perhaps none of it would stick to the front/back of the lens?
As far as putting a polysiloxane dip coating over a UV coat without a primer, why would I want to? I don't want it to stick. I just want it to adhere to the uncoated portions on the polycarb lens. Why apply a UV coating to a polycarb lens as well? It already blocks UV.
Look, I'm just trying to think of a better and easier way to do something. Have any of you (Chris, AWTECH) actually tried what I'm proposing before you just chime in with all this skepticism?
Maybe I should just start using the frames that Johns uses. :)
-Steve
I believe you are missing one of Chris' points. He has a product that you can use on just the edges of the lenses. Why is it that you are focused on dipping the entire lens. Just coat the edges of the lens with Chris' "Edgit". That product is also avialable in multiple colors. You could protect the lens and match the frame color and sell it to the patient as an enhancement or just use the clear version.
What frame line is it that is leaching? I have been doing in house edging for about 16 yrs and have never seen this issue.
Chris, Am I representing your product correctly? Hope so!
The link that Chris provided said nothing about "Edgeit." The link was for Frame Protec or something like that.
If Edgeit or Camoflague or whatever works, then I'm fine with that. Chris - does that seal up the lens and prevent the interaction between zyl and polycarb?
-Steve
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