I have a question. On workshop page 4, #14 you mention "cooling down for 15 seconds before putting the flask on the floor to cool for 20 minutes." What's the advantage over just plunging it in a bucket of water after the button loses it's red color? And if you let it sit too long, isn't it hard to remove the investment?
Depending of course on the metal, normally the button looses its red
color in around five minutes. When I have let it cool for more than
that it definitely has been much harder to remove, even having to use
other tools like hammers, brass brushes and sand blasting.It seams to
me that 20 minutes is too long for gold alloys and silver, but might
be necessary for niquel alloys or similar.