From this thread:
Jack's says practically nothing about what is in stain solution #1. They do, however, give a solubility in water number which is half of the solubility of ascorbic acid. The dosage amounts are double the typical dosage for ascorbic acid. They also refer to it as non-acidic. Ascorbic acid is an acid, though a weak one.
On the other hand the appearance and safety considerations are identical to ascorbic acid. If it isn't ascorbic acid it isn't obvious what else it could be. The solubility number could simply be wrong and everything else just marketing. Or maybe there is something in there in addition to ascorbic acid.
JasonLion said:Jacks #1 is not ascorbic acid, though it works in a related way.
waterbear said:Jack's magic #1, according to the MDSD is 100% a non hazardous propriatary formula. Since it works on iron, and cobalt it is either ascorbic acid or oxalic acid. Since oxalic acid is toxic AND corrosive if ingested, inhaled, or absorbed through the skin in dry form and ascorbic acid is not (it's another name for vitamin c) I would make an educated guess that it IS just ascorbic acid but I have no actual proof of this. However the MSDS for Jack's #1 and for ascorbic acid are strikingly similar!
Jack's says practically nothing about what is in stain solution #1. They do, however, give a solubility in water number which is half of the solubility of ascorbic acid. The dosage amounts are double the typical dosage for ascorbic acid. They also refer to it as non-acidic. Ascorbic acid is an acid, though a weak one.
On the other hand the appearance and safety considerations are identical to ascorbic acid. If it isn't ascorbic acid it isn't obvious what else it could be. The solubility number could simply be wrong and everything else just marketing. Or maybe there is something in there in addition to ascorbic acid.