A method of making phosphorescent fiber having phosphorescent particles composed, by weight, of 55-62. The borosilicate glass composition includes silicon dioxide in a range from about 60% to 74% by total composition weight; boric oxide in a range from about 9% to 25% by total composition weight; aluminum oxide in a range from about 7% to 17% by total composition weight; and at least one alkali oxide in a range from about 2% to 7% by total composition weight. The opposite margin has an edge which bears against the axially opposed sealing surface of the nozzle support ring.