Quote Originally Posted by Tom Hoskinson
Jim, I recommend dissolving the phenidone and catechcol in propylene glycol (PG) as the "A" stock solution.

I eliminate the metabisulfite, it is not needed with the PG as the preservative.
My recommendation would be to keep the meteabisulfite when mixing the stock solution with propylene glycol. It is true that it is not needed as a preservative when mixing with PG, but metabisulfite has another function in the Pyrocat-HD formula, and that is to keep the genral stain as low as possible. When mixed with water metabisulfite produces sulfite and a small amount of sulfite is really important in the Pyrocat-HD formula to keep general stain down as low as possible.

Sandy King