Campden tablets need to be crushed before use. So why isn't Campden sold in powdered form?
Presumably this is either because:
- The dosage required is very precise, and it would be very difficult to measure this out by weight or volume; or
- Campden is unstable in powder form; or
- According to Wikipedia, eight Campden tablets are equivalent to ½ teaspoon of potassium metabisulphite. If this is the case, then perhaps Campden isn't just potassium metabisulphite? In which case perhaps the reason Campden is sold in tablets is because it contains a second ingredient which would otherwise separate from it?