Transition Glasses

Posted by Specscart on April 18th, 2019

Transition lenses or Transitions glasses remain clear at indoors (in the absence of specific threshold of UV ) and darken (changes color to dark gray) at outdoors (on exposure to the specific threshold of UV ). These lenses take about 30 seconds to tint fully and about 2 to 4 minutes to change to the original color.

The Transition lenses are made from many materials and the most common Transition lens materials are glass and polycarbonate sheet ( plastic ).

Working of Transition Glasses:

To know the working in detail, it is necessary to know about the molecular changes that take place within the transition materials and to know the two types of transition lenses separately.

Glass Photochromic or Transition Glasses :

The first transitions lenses were made from glass and the main elements are silver compounds such as silver chloride or silver halide are embedded within the glass substrate which is very in size through the most common size was about 5nm.Here the tinting was due to a chemical reaction and we will know how silver compounds react to create a transition effect.
First of all, one needs to dope silver chloride with copper and at this stage, the glass is bright blue and is not yet transition. So, it is subjected to heat at a temperature of about 600°C to obtain transition properties. Here, the duration will determine the sensitivity of transition molecules.

Now, the subject glass transition lens to a short-wave light, it will start to tint gradually. It means the silver chloride will begin to break into silver and chlorine. This really leads to the darkening process. Again, when you remove the UV light, silver will begin to combine with chlorine and this reaction helps the transitions glasses to retain its original color.

Polycarbonate Photochromic or Transition Glasses :

The working principle behind the plastic transition lenses is different from that of glass. It means these transition lenses depends on carbon-based compounds.

Initially, transition lens manufacturers used pyridobenzoxazinesand now they are using naphthopyrans. Now we will know how naphthopyrans cause the transition effect.

When you expose these plastic transition lenses to a certain threshold of UV radiation, the chemical bonds will be broken, which results the lens to tint. When you remove the UV radiation these carbon compounds will gain their original structure which results the plastic lens to retain its original color.

TRANSITION GLASSES PROS :

1. They are convenient, can use indoors or outdoors.
2. They are available in gray and brown variable tints to suit your personal style.
3. Can save money because of no need to buy separate photochromic prescription glasses and sunglasses.
4. They are available in many styles and also available in most lightweight.
5. They offer continuous UV protection.

TRANSITION GLASSES CONS :

1. In cold weather, it is difficult to adjust.
2. Depending on the brand, they lighten and darken to varying degrees.
3. They don’t work in a car because the windshield blocks the required UV rays. Now a day’s manufacturers have car-friendly lenses in the works.
4. Today’s high-quality eyeglasses with photochromic lenses are a sensible solution for many people.