Smart Lens Technology Forum

[Steve Machol]

The Smart Lens Technology Forum is sponsored and moderated by Transitions Optical. Please feel free to post any questions you have regarding Transitions products, services and promotions here.

[BognorPaul]

Hi,
New to this.
Can Transitions be used in dip coating? Or is it just imbibing?
Paul

[Jim Schafer]

Hello Paul,
Yes, Transitions lenses can be and are dip hardcoated, usually for premium AR processing.
As for imbibition, that is a Transitions technology for making photochromic lenses.
Jim

[BognorPaul]

Sorry Jim
Told you I was new. What I meant was, could a polycarbonate sheet be made photochromic by Transitions by dip coating, or would it have to be imbibed by yourselves?
I want to make something other than a lens blank photochromatic.
Cheers
Paul

[Jim Schafer]

Hi Paul,

Polycarbonate cannot be imbibed with photochromic dyes to a sufficient performance level that is expected by consumers.
Dipping poly sheets into a photochromic bath would not work with bare poly because poly is not chemical resistant. For coated poly you need to treat the surface for adhesion purposes.
BTW, Transitions will only process lenses from our partnered lens manufacturers.
regards,
Jim

[NavyChief]

I was wondering... I've been told that when a patient first takes their transitions home they should place them (frame and all) in the freezer over night. That this gives them a jumpstart, so to speak. Is this true? And could one do this after a few years to reactivate them??

Thanks,

[C-10]

I would like to do a flash mirror on trainsistion but can't find anyone in Canada to do this.
Is it possible?

[Jim Schafer]

First Navy Chief,
I was wondering... I've been told that when a patient first takes their transitions home they should place them (frame and all) in the freezer over night. That this gives them a jumpstart, so to speak. Is this true? And could one do this after a few years to reactivate them??

The only thing you are doing is freezing your lenses. Please smack the person in the head that passed this old wives/urban legend tale on.
Sorry, I get carried away when ever that question comes up. Someone started that as a joke about 15 years ago and it wont go away. It is right up there with putting winter air in your tires so they wont go flat in freezing temps.
Please read the thread on Transitions® and cooler temps. There is a basic photochromics 101 that can explain everything you need to know about organic photochromics used in plastic lenses.

and C-10
I would like to do a flash mirror on trainsistion but can't find anyone in Canada to do this.
Is it possible?
Yes, flash mirrors are possible and fairly popular on Transitions®. Any lab doing AR on Transitions and also offer flash mirrors as products can flash and do mirror's on Transitions.
Optiboard has many members from Canada. If you post your request and location in the General Forum I am sure you will reap many good leads.

[For-Life]

and C-10

Yes, flash mirrors are possible and fairly popular on Transitions®. Any lab doing AR on Transitions and also offer flash mirrors as products can flash and do mirror's on Transitions.
Optiboard has many members from Canada. If you post your request and location in the General Forum I am sure you will reap many good leads.

I know it can easily be done. But I do not think anyone is doing them in Canada. I have had a lot of fighting with the labs here the last few years over that same issue.

[Jim Schafer]

Hi For-Life,
Thanks for the quick response.
I am sure you checked this out but am curious...What about the Carl Zeiss Cool Blue, Cool Gold and Cool Silver? Are they offered in Canada by Zeiss partner labs?
Also, I know this lab is not in Canada, but is just over the river from Windsor, Great Lakes Coating Laboratory in Troy Michigan has done all sorts of flash and mirrors on Transitions for years.
regards,
Jim

[The Spectacle]

is the reason that transitions work differently in different temps because the molecules are expanded and cant open as much in the hotter temps. but in cold weather they are contracted giving more "room" for the molecules to open up and become darker?

[Jim Schafer]

Hi Spectacle,
Here is a laymans explanation of the chemical reaction .....

Photochromism 101
When a photochromic lens is exposed to ultraviolet light (UV) wavelengths present in sunlight, the resulting photochromic reaction causes some of the photochromic molecules to rearrange into an activated form that absorbs visible light. As trillions of these reactions take place, the lens darkens. When UV light is removed, a chemical reaction driven by ambient heat reconverts the activated photochromic molecules to their original, clear form and the lens fades.

The amount of darkening is a function of the competition between the activating and fading chemical reactions, the equilibrium condition established between them, and the specific photochromic molecules and lens substrate. The more activated photochromic molecules that are present, the darker the lens becomes. The degree of darkness depends on the level of available UV radiation driving the activation reaction and the temperature of the lens, which drives the fade reaction.

The level of UV radiation is what primarily controls the activating photochemical reaction in a photochromic lens. The more UV present, the more photochromic molecules are activated and the darker the lens becomes.

Generally, the level of UV radiation is highest at midday and during the summer. Over the course of a few weeks of sunny days in any given season, the level of UV light from midday sunlight does not change significantly. The temperature, however, may fluctuate by as much as 30° F over the same period.

Temperature is what primarily controls the chemical reaction that causes a darkened photochromic lens to fade to its clear state. Lower temperatures slow the fading reaction, causing the number of activated photochromic molecules too build up over time and establish a new equilibrium that favors activated molecules. With more activated molecules present, the lens is darker. Higher temperatures create a faster fading reaction, so fewer photochromic molecules are activated and the lens darkens less.

On hot, sunny days all photochromic lenses will be less dark than on sunny, cool fall days.

Forrest Blackburn, Ph.D.
PPG Industries Inc.

[Craig]

I have printed and emailed to my staff as the best way to explain and understand the heat vs darkening in Transitions.

Thanks for the information.

Craig Chasnov