1. When one buys a sifter, before taking it to the mikvah, one should bring in inside one's house and scrub off the Stickers From Hell. Otherwise, what will surely happen, is that you will be sitting in your car across from the mikvah, kicking yourself for not checking the sifter beforehand, frantically scrubbing the stickers off without niceties like soap and a sponge, searching for that half-finished bottle of water under the driver's seat, then using a combination of said water and spit to get off the stickiness, scraping it off with a pen you found buried under a mound of tissues, and then finally using your skirt to get off the remaining crud. The skirt worked well, by the way. Not that I would know.
2. Do not buy the sifter with the thingy that you have to squeeze with your hand. It hurts.
3. Do not ignore the sticker (yes, the one you furiously scrubbed off in #1) that says, "Don't wash this!" In fact, they are not just joshing you. They mean it. When one washes a sifter, the water turns the little flour molecues that are left in the sifter into dough. Thus, it becomes nearly impossible to reuse the sifter, what with the dough stuck in the crevices. If you ignore the sticker, you will surely have a conversation similar to the following:
Donny [having just washed the sifter, after spending thirty minutes sifting two cups]: Huh. You can't wash sifters. Now all the flour turned into dough.
Me: Oh really? So that's why it said, "Do not wash." Huh.
4. If you DO insist on washing the sifter, do not then attempt to take it apart and clean it. What will happen if you do that, is you will end up throwing the sifter away.