Spectrum Nuggets changed my glass melting experience instantly. It fines out in a few hours probably because of the size and shape of the nuggets. The glass is so clear I had to say it is right there with the lead crystal I blew in Finland. The working time is plenty good. This is perfect for the small garage band glassblower, it is no fuss and hasn't cracked from any frit or rod I have bought. If you are still melting bottle glass and using additives throw it away and move up 20 years.