The Eco Barrier is between the fluorescent powder and the glass wall, or in the case of uncoated colored glass a transparent coating. The Eco barrier, typical in fluorescent
lamps, prevents mercury atoms from combining with sodium in the glass so less mercury is needed. The Eco barrier also protects uncoated glass from "outgassing" during operation, completely eliminating the need for special processing. It also greatly reduces the amount of staining typically found with uncoated colored glasses.