Do minerals lose effectiveness? Some do!

Some brewers worry that their brewing minerals have been sitting around too long. Let's look at which minerals you should be concerned about freshness with.

The following list of minerals do not lose effectiveness:

• Gypsum

• Epsom Salt

• Table Salt

• Baking Soda

• Chalk

In the case of chalk, its 'effectiveness' is quite debatable unless it is properly dissolved into solution with CO2. In my opinion, chalk is not effective in most brewing usage.

The listing below are minerals that may loose effectiveness over time:

• Calcium Chloride

• Pickling Lime

• Magnesium Chloride

Calcium chloride is highly hygroscopic which means it sucks up water from its surroundings. Moisture from the air is the main water source. The calcium chloride doesn't really 'loose' its effectiveness, it just gains weight. So if you were assuming it was in either the anhydrous (water-less) or dihydrate forms, the amount of calcium chloride delivered per unit weight is decreased due to extra molecules of water absorbed into the mineral. Its diluted. Moral of the story: keep in a tightly sealed container and avoid any water or moist air contact.

Pickling lime is a bit different in that it doesn't absorb water into the molecule. It reacts with CO2 in the air to eventually turn the lime into chalk. Since the lime is in solid form, its ability to react with CO2 in the air is very low. So the effectiveness of lime is relatively constant, but can be accelerated if the lime is in contact with moist air. Moral of the story: same as above.

Magnesium chloride is also hygroscopic. But it appears that it stabilizes to a relatively constant hexahydrate form. At typical room-temperature, it appears less likely to gain or lose water molecules. So it probably doesn't really change much. Moral of the story: Don't worry about this one too much.

So keep these minerals in air-tight containers and replace them if their appearance changes.