Casting weight table wax to silver and so on…
Casting are normally 5% smaller than the master, it doesn’t normally make any difrance but you can do it in some cases ie; If you make a ring it will shrink one size so make your master one size bigger.
Ensure you find out how much they will charge postage do not forget to put that in with your pricing, unless you are able to pick it up.
If you don’t put your own sprew on ur master they will charge you for putting one on.
Picture of a master with sprew
Alway imagine the hot metal runing in to your casting like water, if it has to go back on it’s self it doesn’t cast that well and your chance of pit holes increases.
I use Abt for my castings you can find them at http://www.abtdesign.co.uk/