| 摘要 |
PROBLEM TO BE SOLVED: To improve a production efficiency of a perform by suppressing coloring of a core. SOLUTION: In a method for producing a preform for glass fiber, a columnar glass, at least a part of whose upper face is glass for a core G1, is placed in the inside of a cylindrical body 1 having a bottom with a nozzle 2, is heated, and is extruded through the nozzle by a plunger 3 which is pressed against the upper surface of the columnar glass. A contact part 3A of the plunger 3 which makes contact with the glass for a core G1 is made of platinum, gold, a platinum alloy, or a gold alloy. |
