For Jim Shaffer

[chip anderson]

Jim:
You have told us that our technique of freezing transitions is an old wives tale, and it probably is.
Another old wifes tale for you to expose:
Does exposing transitions (especially those that though new do not seem to be working properly) to UV (as in a black light) for a period of time enhance thier performance?

Chip

[Cindy Hamlin]

Chip,
Since this is a Transitions question I thought this the appropriate forum for it.

[Jim Schafer]

Hi Chip,
I hope all is well.

Transitions and all organic (non glass) photochromic lenses activate from a chemical reaction started by UV light, some products out there may also activate from low level visible light. These type of lenses usually have a indoor fixed tint. All will react the same with every activation cycle adding wear and tear on the properties of the lens. It is very slight but after thousands of activations it add up.

A blacklight is overkill, it activates the photochromic layer to the darkest it will ever reach at that wavelength of light. Some blacklights may even make the lens activate at a different color (more blue because the orange dyes were not activated as strongly)
But, just like putting the lens in a fridge, it is a one time event, it wont help the lens reach that darkness again at normal daylight exposure and ambient temperatures.

There is a testing device called a Q-Panel. It is also called an accelerated aging test. It is destructive because it uses a panel of UV bulbs that mimics solar and environmental damage..depending on what wavelengths of bulbs and the conditions chosen (heat, salt water, etc). What ever object you are testing is placed in the panel for a set amount of time and measurements are taken at the end of each cycle. From that you can create tables predicting changes to expect over time at certain conditions.

So by saturating a plastic lens with UV blacklight, you are starting to fatigue a lens. Granted you have to do this hundreds of times, but it does weaken a few molecules at a time...

A photochromic glass lens could and was conditioned back in the day. A UV light was good for jump starting. A photochromic glass lens that was several years old could also be heated at an elevated temperature and its clear to darkening ability returned. Glass is a whole different animal. Every time it runs through an activation cycle, it returns to slightly darker indoor transmission. After a 18 months of average use, its indoor transmission was around 70% (30% tint).

My guess is that carry over from when glass ruled the day is where the blacklight jumpstart came from.

have a great day,
Jim

[obxeyeguy]

Thanks for the explanation Jim.


ALERT!!! Thread Hi-jack!!

Just needed to make that wakie-wakie thread disappear from the main menu. Sorry all.

[bhess25]

i happened to like that wakie wakie thread!!!