Bathroom Month: The Grout Chore, Part II

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.

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

Comments (5)

so the broken grout i have along the EGDE of the tub is okay to replace w/caulk?

If you don't mind absorbing some caulk through your skin ;) and you keep short finger nails, a finger tip will smooth caulk in the same fashion as an old cc. Also, if you don't have or want to skip the masking tape (more eco friendly in my book), fresh caulk is easily wiped away with a wet rag. My dad taught me those two tricks and from experience a steady hand and a wet rag get the job done.

Thanks for the AFM Safecoat caulk tip, I didn't realize they did anything more than paint!

I was researching this type of repair earlier this week, and found on the GE Silicone & Sealants website advice to fill the tub with water so it pulls the furthest distance from the wall.

How long has mildew-free caulk been on the market, and why does everywhere I live tend to have mildew growing inside the caulk (i.e. cannot be scrubbed out)?

drmeglet -- the quick and dirty way to "fix" mildewed caulk is to cover it with another layer. Of course, it grows through, but it looks clean and fresh long enough to get another renter in. That's why you need to get it all out of there before replacing it.

DahliaCactus -- you've got that right. Get rid of any loose stuff, then apply a fresh bead of caulk at the seam.

If I've currently got mildewed caulk, is there a tool for removing that as well? Or do I use the grout rake on the caulk?