Vintage Japanese “Tokyo Gas Yarn” Enamel Sign. Vintage Japanese “Tokyo Gas Yarn”. = Blue Fuji Seal/Stamp (Thread & fibre Company name). = Tokyo Gas Thread/Yarn (Product name). = Fuji Spinning Products. Please check out my other listings for more Japanese vintage, retro, industrial and antique bits. Gas thread (gasuito) is a thread in which fine fluff is burned by gas or electric heat. Gas thread is a thread that is made by passing the thread through gas fire or electric heat to burn the fluff. Since the fine fluff is burned, it has a little gloss and feels good to the touch. The name comes from the fact that it is passed through a gas flame, and the raw material for gas thread is mainly cotton thread (cotton sewing thread). In addition to sewing and woven fabrics, gas threads may also be used for squid fishing. When this gas yarn is mercerized by passing it through caustic soda, it becomes a mercerized yarn having a silky luster.