>Hi all
>can anybody give me the CAS number for the correct Sodium Metaborat to make
>Pyro part B?
In Europe Sodium Metaborate can be difficult to find and expensive.
It tends to be an unstable chemical too, and doesn't keep very well.
A solution of Sodium Metaborate for PMK Pyro solution B, as well as
for any other formula where it might be present, can be obtained as follows:
300g Sodium Metaborate in dist. water up to 1000 ml = 39g Sodium Hydroxide
+ 180g Sodium Tetraborate Decahydrate (Borax) in dist. water up to 1000 ml
If Borax doesn't dissolve easily, double the water and accordingly
double the amount of concentrated solution B you put in the working solution.
This is what I do to make my PMK Pyro B and works perfectly fine (and cheap).
The pH matches exactly Gordon Hutching's indications.
A small undissolved deposit may form in the bottom of the B bottle:
it can be filtered, but won't do any harm.
Francesco Curcio
Milano Italy