There was an article in Rock and Gem magazine some time ago about
someone who had developed a method to avoid firescale in his cast
sterling (Indian pots I think). The main element was that he burned
scraps of paper to scavenge the oxygen around the flask. Basically,
he placed a few bits of paper inside a flask larger than he had
filled with investment. At some point after the pour he dropped the
hot flask into the larger flask and covered the top. The hot flask
burns the paper, using all the oxygen and stopping the formation of
firescale.
Anyone actually do something like this?
Flint