In the mid-twentieth century, radioactive materials was usually included within the paint, so it might continue to glow without any publicity to mild. Radium was often used but produced small amounts of radiation outside the watch which may have been hazardous. Tritium was used as a alternative, for the reason that radiation it produces has such low energy that it can’t penetrate a watch glass. However, tritium is expensive—it must be made in a nuclear reactor—and it has a half-lifetime of only about 12 years so the paint stays luminous for only some years. For other purposes, luminous paint is typically used on analog displays, however no radioactive material is contained in it.
This methodology is accurate sufficient for use only at fairly excessive latitudes. Main Article ISO 6425Water-resistance ratingSuitabilityRemarksWater Resistant or 30 mSuitable for on a regular basis use.
These watches are typically called diving watches when they’re suitable … Read More