Quote Originally Posted by Gerald C Koch View Post
Sodium metaborate is not any different from any other chemicals. You must know the hydration form called for in the formula.
The confusion comes from the fact that tetrahydrate can mean two different forms of hydration (NaBO2 * 4 H2O and Na2B2O4 * 4 H2O), something which is not an issue with most other compounds including Sodium Carbonate. The Xtol Concentrate thread referenced by Alan Johnson sheds some light on this.

@Alan: Moersch does sell Sodium Metaborate through Fototechnik Suvatlar, see my previous post here in this thread.