Why is Campden sold in tablet form?

Question

Campden tablets need to be crushed before use. So why isn't Campden sold in powdered form?

Presumably this is either because:

1. The dosage required is very precise, and it would be very difficult to measure this out by weight or volume; or
2. Campden is unstable in powder form; or
3. 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?

Answer 1

The answer is in the Wikipedia article you referred to: the rest is filler, an inert ingredient which has no influence in the process.

It seems that this specific form of metabisulphites is something that is mostly used in Great-Britain and the US. Here in Europe brewing stores sell potassium- or sodium-metabisulphite in pure form, as a powder, in weights varying from 100 g to 1 kg.

Since 1 tablet contains 0.44g, it can be indeed simpler to measure. E.g. when racking 10l wine, 1 tablet is enough to add protection against oxygen and light contamination. Personally, I have bought a precision scale, because when brewing there are other things that sometimes need to be measured in small amounts.

This article gives the history of the Campden tablet. This probably shows the main reason why it is not used in this form in Europe.

Answer 2

The Campden tablets I use in Australia dissolve in my strike water, so I don't understand why they would need to be crushed.