(Image credit: Apartment Therapy )
At this point, you've used our Part I post to assess the state of your grout.

Today's post is for those of you with grout in basically good shape, but a bit of nasty stuff growing on the caulk. We're going to go over how to use a grout rake, the tool shown after the jump, to prepare the corners of your shower for a fresh coat of mold- and mildew-free caulk.

In this series, we're also going to sort out the difference between caulk and grout, and where to properly use each one. Today, we're focusing on caulk.

You can use a grout rake, the tool shown below, to prepare the corners of your shower for a fresh coat of mold- and mildew-free caulk.

Caulk is flexible and rubbery. It comes in two basic variations: acrylic and silicone. Green choices include AFM Safecoat Caulking Compound. We also like DAP Kwik Seal 3.0; it's not particularly eco-friendly, but it cures in 3 hours, whereas other caulks need 24-36 hours before they touch water.

Caulk's function is to stretch a bit and prevent small cracks from forming due to expansion and contraction. Even teensy cracks can cause big water damage thanks to our friend capillary action. Therefore, caulk belongs where two planes meet -- as in the corners of your shower -- or where two dissimilar materials meet, such as the ledge where the tub meets tile, as shown by the green line above. It does not belong anywhere else. It especially does not belong around individual tiles.

(Image credit: Apartment Therapy )
You might find advice to the contrary, but trust us: grout does not belong in those joints. So tape down a few old cardboard boxes in the tub, get a grout rake from the hardware store (shown left; buy one with a carbide tip), scrape the grout out of the corners, and then caulk away. Tip: to get a perfect looking joint, use masking tape on each side of the caulk, then shape it while it's still wet with the corner of an old credit card. Remove the tape before the caulk cures.

base image by garann via sxc.hu; illustration Jonathan Bean