Barrier Coatings

What is a Barrier Coating?

A barrier coating is a protective layer of nano-sized particles that act as a shield against forces
and electrochemical reactions that would otherwise take place, resulting in a darker tube.

1. Mercury sequestration: as a neon tube operates, there is a tendency of mercury to condense
underneath the phosphor layer on the cold spots in the tube. This increases the mercury that
must be put into the tube, but also puts in place a nasty chemical reaction....

2. Mercury-Sodium reaction: Sodium is present in nearly all glasses as NaO. This sodium will
react with the mercury ions as the lamp operates. The result is a reduction in available mercury,
but also a dark gray stain that covers the whole tube.

3. Ion Bombardment: The newer rare-earth phosphors are more resilient than any, but they are
still susceptable to fracture and damage by the ions in the plasma stream. Because the phsophor
layer is now physically protected, this damage is greatly mitigated.

What is the Benefit of a Barrier Coating?

The Barrier Coating effectively protects the phosphor and the glass. As such, the two
main causes of the loss of brilliance are greatly mitigated. Benefits include:

-Increased Brightness over time (lumen maintenance)
-Decreases the quantity of mercury required
-Prevents staining and darkening of the tube