Lenses fall out in cold weather?

[DreamWeaver]

Hello,

I was wondering if it's normal for eyeglass lenses to fall out in cold weather?,
I have a pair of prescription sunglasses (metal frames) that i keep in my car glove compartment, Iv'e never had this problem in the summer but lately the lenses just keep popping out?, the screws are tight, it's like the frame expanded!, Is this normal in cold weather or was the lenses poorly sized?

Thank You...

[QDO1]

Hello,

I was wondering if it's normal for eyeglass lenses to fall out in cold weather?,
I have a pair of prescription sunglasses (metal frames) that i keep in my car glove compartment, Iv'e never had this problem in the summer but lately the lenses just keep popping out?, the screws are tight, it's like the frame expanded!, Is this normal in cold weather or was the lenses poorly sized?

Thank You...

Sounds like poorly fitted lenses

[finklstiltskin]

Sounds like poorly fitted lenses

I agree. I wonder if the lab would re-edge the lenses. The cold weather is apparently causing the lenses to contract a bit, enough to slip from the frame. If they were edged a little larger, I doubt this problem would continue.

The Lord sayeth it to be so.


Fink:shiner:

[SpecialT]

I agree as well. It is not typical and it seems likely that the lab would redo your lenses. Interesting observation though, I will pay more attention to see if I notice similar temperature related issues.

[chip anderson]

If lenses are new, possibly what each one of my colleges has suggested about a lab remake would be indicated. However plastic, poly, and other plastic lenses lose polymer after time and shrink. The cold weather can cause further temporary shrinkage. If lenses are not new, go by your friendly independent optician and have him line the eyewire with lenswasher, adhesive if possible.

Chip:hammer:

[drk]

Put the lenses in hot (not boiling) water for 10 minutes and they will enlarge again, and then they will fit tightly. Try to avoid keeping them in the car.

[CME4SPECS]

Put the lenses in hot (not boiling) water for 10 minutes and they will enlarge again, and then they will fit tightly. Try to avoid keeping them in the car.

Great humor drk!

[fjpod]

Besides the normal steps for shrinking the frame (assuming it is zyl), I have used a tip I picked on the board, namely put a coat of clear nailpolish into the bezel of the frame (metal or plastic). Let it dry, then either snap fit the lenses or use a LITTLE heat. The lenses will hold REALLY WELL!!

[QDO1]

If lenses are new, possibly what each one of my colleges has suggested about a lab remake would be indicated. However plastic, poly, and other plastic lenses lose polymer after time and shrink. The cold weather can cause further temporary shrinkage. If lenses are not new, go by your friendly independent optician and have him line the eyewire with lenswasher, adhesive if possible.

Chip:hammer:

I banned lenswasher and glue from my labs years ago, the tech's didnt love me, and eventually they learnt that cutting the job the right size is the right way to go. I have lens washer in practice to patch up the poor jobs brought in from elsewhere. I have found over the years that it is the little things that count - nutlock on the screws, oil in the joints, properly well mounted lenses. People remember a job when it goes wrong, its damm hard to get them to remember the one that was perfect. I hand my patients a care slip with their new product - personalised. It mentions about all the little extra things we do on the back of the slip. I reccomend servicing- 2 weeks, 6 months... which I do for free... patients percieve this as value added, and I manage to avoid a lot of the problems associated with spectacles. I also manage to bash home the correct way to clean the spectacles

[Lewy]

If the lenses are tinted, the tinting process initially causes the lens to expand. If the lab then took a tad of the lenses to fit them into the frame this could also add to the problem. Whenever I have to tint lenses, especially a very dark tint, I leave the lenses out for at least ½ a day before assembling.

Lewy

[Chris Ryser]

The cold weather can cause further temporary shrinkage. If lenses are not new, go by your friendly independent optician and have him line the eyewire with lenswasher, adhesive if possible.
Chip:hammer:

Just think about railway tracks amd bridges which are built with a space at the joints because they contract and expand with heat or cold. So does plastic.

In the optical there has always bee a tendency to make the [;astic lenses a touch to large so that, as Chip explained you can titghen the screws a bit more.

In case of a plastic frame it can help yo heat the frame good and hot tand then quickly cool it off under running cold water. This will shrink the frame a bit.

[hcjilson]

Just think about railway tracks amd bridges which are built with a space at the joints because they contract and expand with heat or cold. So does plastic.

In the optical there has always bee a tendency to make the [;astic lenses a touch to large so that, as Chip explained you can titghen the screws a bit more.

In case of a plastic frame it can help yo heat the frame good and hot tand then quickly cool it off under running cold water. This will shrink the frame a bit.

The problem stems from today's technology. Lenses that are processed from a tracing are exactly the size of the eyewire.( to a hundreth of a millimeter) There is no "fudge" factor to leave them a tad large, consequently when a lens contracts from either age or temperature, it comes out of the eyewire.Eyewire screws on metal frames loosen for this very same reason. There is no counter pressure to keep them tight.

In a perfect world we could ban eyewire washer and lens tight from our labs, but the need for speed and accuracy outweigh overriding todays lens processing equipment.Its an interesting dilemma.

[fjpod]

The problem stems from today's technology. Lenses that are processed from a tracing are exactly the size of the eyewire.( to a hundreth of a millimeter) There is no "fudge" factor to leave them a tad large, consequently when a lens contracts from either age or temperature, it comes out of the eyewire.Eyewire screws on metal frames loosen for this very same reason. There is no counter pressure to keep them tight.

In a perfect world we could ban eyewire washer and lens tight from our labs, but the need for speed and accuracy outweigh overriding todays lens processing equipment.Its an interesting dilemma.

I've been doing patternless edging for years, and I haven't found this to be a problem. Of course, proper lens sizing is critical and all the systems require edger/tracer calibration to get it right.

I also think lens washers should be illegal or against ANSI standards. Laquer in the bezel works really well though.

[drk]

Great humor drk!

I'm not joking. A lab owner told me to do it years ago; he muttered something about improper curing (which I have no idea still what he meant).

Despite the natural supposition that they would have to come back over and over, I truly have had near zero returns after doing it. Maybe I've had an amazing string of success, but I've done it numerous times without a single negative consequence.

Wouldn't do it on an AR lens, of course.

What do you all think of this?

[hcjilson]

fjpod,
Laquer's OK but lens washers should be outlawed.....do I have that correctly? And if you've never had a problem with lenses not fitting in the eyewire, how is it that you are so conversant with the historic solutions? :):)

[DoubleD]

Iagree with Chip.

Actually known for years, all MONOMERS lose plasticizers over a few years, and do shrink some what.
I always make sure we have lens washer on hand for those three plus year old glasses coming in loose. I personally prefer the double sided tape type-holds up great.
Denny

[fjpod]

fjpod,
Laquer's OK but lens washers should be outlawed.....do I have that correctly? And if you've never had a problem with lenses not fitting in the eyewire, how is it that you are so conversant with the historic solutions? :):)

IMHO laquer holds better. It doesn't fail suddenly like washers which pop out.

I'm so conversant because patients bring in eyewear that they have had made elsewhere all the itme.:)

[Chris Ryser]

I'm not joking. A lab owner told me to do it years ago; he muttered something about improper curing (which I have no idea still what he meant)?

I can tell you what he meant. When a lens, CR39, is not properly cured it will not tint as well a properly cured one. If you tint 2 lenses at a time one will go dark fast and the other one just wont go as dark.

Thsi can be corrected by heating the lens in an oven for an hour or two and give it an aftercure. It will then tint properly.

[Chris Ryser]

Eyewire screws on metal frames loosen for this very same reason. There is no counter pressure to keep them tight.

There is also a solution buy only for the handy optician who does not want to use liners or laquer.......................take out the screw and file the block down for about 1mm or as needed and your lens will be tight again.

[drk]

Chris:
What is "curing" anyway? How is it physically achieved? Does hydration have anything to do with it? Is it wrong to drop shrunken lenses in hot water to expand them?

[QDO1]

There is also a solution buy only for the handy optician who does not want to use liners or laquer.......................take out the screw and file the block down for about 1mm or as needed and your lens will be tight again.

i despise that practice too, if your car mecahnic took that attitude with your brakes, you would be in big trouble. why destroy a quality frame by bodging it up, cos the glazer cut the lens too small?

[QDO1]

im sorry, but quote me expansion coeficients before you say that this will be a problem. if the lens is the wrong size, then it is the wrong size. if modern machinery cant do the job anymore, we are not progressing, and we have the wrong machinery

[Chris Ryser]

Chris:
What is "curing" anyway? How is it physically achieved? Does hydration have anything to do with it? Is it wrong to drop shrunken lenses in hot water to expand them?

Monomers and or resins are the liquid raw plastic materials.............The curing process is to harden them chemically into a solid piece. To do this you use an initiator that will start the curing process which will run its time. Usually it is a thermo curing process which starts with heating up the material, then at some point you have to cool it and then heat it again and so forth. (its actually a lot more complicated)

Other are started with some radiation as UV light at 360nm and the latest are daylight initiators...........as used by dentists to make the light cured fillings.

I have never heard that hot water would expand a lens..........so I am no jusge on taht one. I do know that a CR39 that has orange peel (usually from polishing) can be inserted into the glass bead frame heater and the orange peel disapears after a while.

Raq Polycarbonate comes in pellets that are heated up and then injected into a mold when liquid, and gets hard a again when cooled off. There is no curing involved. It is actually the easiest and cheapest way of making a piece of finished plastic material.

[dv]

Just think about railway tracks amd bridges which are built with a space at the joints because they contract and expand with heat or cold. So does plastic.

In the optical there has always bee a tendency to make the [;astic lenses a touch to large so that, as Chip explained you can titghen the screws a bit more.

In case of a plastic frame it can help yo heat the frame good and hot tand then quickly cool it off under running cold water. This will shrink the frame a bit.

Optiboard to the rescue as always!!! Lab cut lens too small but I didnt want to waste more time having to send the job back to the lab and make the patient wait more time than normal. Heated the frame with the lens in it (no AR) then held it under cold running water and its as if it were cut perfectly.

Thanks!!

[MikeAurelius]

Why post to a 10 year old thread????