Don't bring loose matcha in a paper envelope—it'll absorb moisture and clump. Skip the glass jar if you're clumsy; a stainless steel or plastic container is safer for a commute. Also, don't forget a dry spoon: using a wet one introduces moisture and speeds up clumping.

And whatever you do, don't add matcha to boiling water at your desk. It's the number one way to ruin a cup. Take the extra ten seconds to let the water cool.