"T swiss T" what does it mean? Info here:

Joined: May 2nd, 2005, 3:20 pm

June 6th, 2009, 1:21 am #1

A nifty bit of info:

In order for timepieces to be read in the dark, a luminescent material is laid on the dial indexes and hands. Generally speaking, the emission of light is either of photoluminescent type (determined by a exciting luminous radiation) or of radioluminescent type (determined by the radioactivity of the material).

Timepieces featuring radioluminescent emission are mostly designed for very specific uses : military watches, professional divers watches, etc. In this case, the use of radioactive material is strictly defined by ISO 3157 Standard which allows only two types of radionucleides : tritium (3H) and promethium (147 Pm). It is important to specify that these radionucleides emit a radiation of low energy.

ISO 3157 Standard allows an optional marking for timepieces emitting less than a certain value. The marking may be made on the dial as follows :

<img height="34" src="http://www.fhs.ch/images/t_sm_t2.gif" width="150" alt="t_sm_t2.gif">deposits activated by tritium : T

deposits activated by promethium : Pm

On the other hand, timepieces with a higher value, such as divers' watches, must be marked as follows :

<img height="34" src="http://www.fhs.ch/images/swiss25.gif" width="150" alt="swiss25.gif"> deposits activated by tritium : T 25

deposits activated by promethium : Pm 0,5

The indication "T Swiss made T" means that the watch is Swiss and contains a certain quantity of tritium that emits less than 227 MBq (7,5 mCi).The indication "Swiss T<25" means that the watch is Swiss and contains a certain quantity of tritium that emits less than 925 MBq (25 mCi).</FONT>

<img height="42" src="http://www.fhs.ch/images/swiss26.gif" width="150" alt="swiss26.gif">Most of the Swiss watches use a light emission of photoluminescent type. Some of them bear the optional marking "L Swiss Made L" to indicate it.

Because every one needs at least 10watches