Keep Your Powder Dry
Moisture in the air gradually robs baking powder of its strength. One way to slow the process is to keep your baking powder in an air-tight container. King Arthur Flour sells a cool-looking stainless steel canister with a lock-seal acrylic lid and even offers a combo deal: the canister plus 8 ounces of MaineBakewell Cream baking powder, a New England favorite that contains no aluminum.
King Arthur Flour baking powder canister, $11.75; with baking powder, $12.50, plus shipping and handling, from https://www.kingarthurflour.com , or call (800) 827-6836.