Mold in Your Shower or Bathtub? Do This Now

Dark spots creeping along the grout lines, a gray-black stripe in the caulk where the tub meets the wall: almost every bathroom gets there eventually. Bathrooms are warm, wet, and often poorly ventilated, which is exactly what mold likes, especially through long, humid DFW summers. The good news is that most shower and tub mold is a surface problem you can handle in an afternoon. Here's how to tell what you're looking at, clean it safely, and keep it from coming back.

Mold, mildew, or soap scum?

Before you grab a cleaner, take a closer look.

• Soap scum is a whitish or gray film, usually on glass, tile, and the tub surface. It feels chalky or waxy and wipes away with the right cleaner and some scrubbing.
• Mildew is a type of mold that tends to stay on the surface. It often shows up as gray, white, or light black patches, typically in corners and on grout, and usually cleans up fairly easily.
• Mold can be black, green, or even pinkish-orange. It tends to look fuzzy or slimy and can grow into porous materials like grout and caulk, which makes it harder to remove.

You don't need a lab test to deal with the spots in a typical shower. Treat any of it as something to clean and then prevent.

Safety first

Bathroom cleaning chemicals are strong, and bathrooms are small rooms. A few rules before you start:

• Ventilate. Turn on the exhaust fan, open a window if you have one, and keep the door open.
• Protect yourself. Wear rubber gloves and eye protection. A mask is a good idea if you're sensitive to odors or dust.
• Never mix bleach with ammonia, or with vinegar or any other acidic cleaner. These combinations can release toxic gases. Use one product at a time, and rinse the surface thoroughly with water before switching to a different one.
• Read the labels. Some cleaners can damage natural stone, colored grout, or certain tub finishes. Test a small hidden spot first.

Step-by-step cleanup

Grout:

• Apply a mold-and-mildew bathroom cleaner (or a single cleaner of your choice) and let it sit for the dwell time on the label.
• Scrub along the grout lines with a stiff nylon grout brush or an old toothbrush. Avoid wire brushes, which can scratch tile and gouge grout.
• Rinse well with clean water and dry the area with a towel.

Tile:

• Spray, wait, and wipe with a non-scratch sponge, working from the top of the wall down.
• Rinse thoroughly so no residue is left to attract soap scum.

Tub or shower pan:

• Check what your tub is made of. Acrylic, fiberglass, and enameled surfaces need non-abrasive cleaners and soft sponges.
• Pay attention to the drain area, the overflow plate, and the corners where water pools.
• Rinse and dry. Don't forget to wash or replace the shower curtain liner and bath mat, which hold moisture and grow mold too.

Black spots in the caulk? Replace it

This is the part most people don't want to hear: if mold is showing up inside the caulk bead, cleaning usually won't fix it. Caulk is soft and slightly porous, and once mold grows into it or behind it, surface cleaners can't reach it. You might lighten it for a few weeks, but it comes right back. Caulk that's peeling, cracked, or pulling away from the tub also lets water get behind it, which is a bigger problem than the spots themselves.

How to recaulk a tub or shower

• Remove all the old caulk. Use a utility knife or caulk removal tool, and take it down to bare surface. New caulk won't stick well to old caulk.
• Clean the joint. Scrub away any mold and residue, rinse, and wipe with rubbing alcohol to remove soap film.
• Let it dry completely. This is the step people rush. Give it time, ideally with the fan running. Trapping moisture under fresh caulk defeats the purpose.
• Tape the lines with painter's tape on both sides of the joint for a clean, straight edge.
• Apply a kitchen-and-bath silicone caulk labeled for mildew resistance in a steady, continuous bead.
• Smooth it with a caulk tool or a gloved fingertip, then pull the tape while the caulk is still wet.
• Wait before showering. Follow the cure time on the tube, which is often a full day or more.

Tip: some pros fill the tub with water before caulking the tub-to-wall joint so the tub settles to its loaded position. Drain it after the caulk cures.

Keeping mold from coming back

Mold needs moisture. Take the moisture away and it struggles. DFW summers bring plenty of humidity, and a bathroom that never fully dries out will grow mold no matter how often you scrub.

• Run the exhaust fan during every shower and leave it on for a while afterward until the mirror and walls are clear. If your fan is noisy, weak, or doesn't seem to pull air, have it checked.
• Squeegee walls and glass after showering. It takes less than a minute.
• Fix drips and slow leaks. A dripping faucet or showerhead keeps surfaces wet all day.
• Seal grout periodically with a penetrating grout sealer so it absorbs less water.
• Leave the curtain or door open after showering so air can circulate, and hang towels to dry outside the shower.

When it's more than surface mold

Some signs mean water has gotten into the wall, and no amount of bleach or caulk will solve that:

• Drywall around the tub or shower that's soft, bubbling, or stained.
• A musty smell that seems to come from the walls or floor, not the shower itself.
• Mold that keeps returning behind or under tiles even after recaulking and regrouting.
• Loose tiles or grout that crumbles when touched.

In those cases, the right call is a mold remediation specialist who can find and fix the moisture source and remove contaminated materials properly. If you or anyone in your home has health symptoms you think may be related, see a doctor.

Once the moisture problem is fixed, H2G can re-caulk and reseal your tub or shower and handle drywall patching to put the bathroom back together. We also offer deep cleaning, including an eco-friendly products option, and we can fold caulking and other small repairs into the same visit for homeowners across Irving and DFW.

Quick answers

Can I clean black mold out of caulk? Usually not for long. Cut out the old caulk and apply fresh.

Can I mix bleach with other cleaners? No. Never mix bleach with ammonia or vinegar-based or acidic cleaners.

How do I keep mold from coming back? Run the exhaust fan during and after showers, squeegee, fix drips, and keep caulk and grout sealed.

When should I call a pro? If drywall is soft or stained, walls smell musty, or mold keeps returning behind tile, call a mold remediation specialist. See a doctor for health symptoms.