Mold in caulk of shower

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BashDash
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Mold in caulk of shower

Post by BashDash » Sat Jul 28, 2018 6:12 am

Hi all, novice DIYer here. Have some mold in caulk of shower and am trying to remove without removing caulk and then recaulking. I realize this may have to be done but am trying to avoid. I read on some DIY blogs that you can soak some cotton balls in bleach/water solution and then place on the caulk for two or three hours. I tried this and left it overnight but there is no noticeable effect. Before I try again I figured I would check in here. Thanks!!!

PFInterest
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Re: Mold in caulk of shower

Post by PFInterest » Sat Jul 28, 2018 6:27 am

Remove scrub and recaulk.

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mrc
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Re: Mold in caulk of shower

Post by mrc » Sat Jul 28, 2018 6:37 am

Bleach. The tricky part is getting it to stick long enough to work. A couple hours. I've used a baking soda/bleach paste with good results. You'll also want to correct the conditions that enable the mold to grow. If you remove the old caulk (not easy) and reapply, the new caulk will eventually mold unless you address the favorable conditions.
If it’s not long term it’s small talk

mouses
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Re: Mold in caulk of shower

Post by mouses » Sat Jul 28, 2018 6:50 am

BashDash wrote:
Sat Jul 28, 2018 6:12 am
Hi all, novice DIYer here. Have some mold in caulk of shower and am trying to remove without removing caulk and then recaulking. I realize this may have to be done but am trying to avoid. I read on some DIY blogs that you can soak some cotton balls in bleach/water solution and then place on the caulk for two or three hours. I tried this and left it overnight but there is no noticeable effect. Before I try again I figured I would check in here. Thanks!!!
What works with my bathtub is taking a few sheets of toilet paper, rolling them up and soaking them in bleach (not diluted, just as is from the bottle) and wedging them against the line of caulk at the top of the tub. I leave them there for several hours or overnight with the door to the bathroom closed so pets etc, don't get harmed and to keep in bleach fumes. Sometimes I will have to redo a spot.

I don't know how you would get those to adhere to vertical caulk. Maybe masking tape them on.

Mitchell777
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Re: Mold in caulk of shower

Post by Mitchell777 » Sat Jul 28, 2018 7:08 am

I had a real problem where the tub meets the tile, very dark and unsightly caulk. Several hours of bleach soaked cotton balls and it was pure white again. On the other hand I tried the same on a few spots between tiles and it did not work at all.

Yooper16
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Re: Mold in caulk of shower

Post by Yooper16 » Sat Jul 28, 2018 7:10 am

Try a gel type bleach agent or as suggested make a paste.

Try to avoid using any caulk that has a latex base--- mold likes latex. Use a 100% silicone or the somewhat newer polyurethane type caulks. Both will be a bit less prone to moldy/mildew, but are not as user friendly.

Ventilate during and after use.

Also, soap residue is one of major causes of the problem. Rinse and wipe down the walls, corners etc after use.

Keep in mind that any "scrubbing" on the caulk may/will start to loosen the adhesion which eventually allow moisture to get behind the caulk and will lead to more significant problems.

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Bengineer
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Re: Mold in caulk of shower

Post by Bengineer » Sat Jul 28, 2018 7:21 am

mrc wrote:
Sat Jul 28, 2018 6:37 am
... You'll also want to correct the conditions that enable the mold to grow. If you remove the old caulk (not easy) and reapply, the new caulk will eventually mold unless you address the favorable conditions.
And when you do replace the caulk, do a careful job of removing the old caulk (and inevitable bits of grout) use the best 100% silicone with a mold inhibitor you can find.

I just finished repairing my leaky shower valve with new seals and lapping the face of the valve seat and replacing the grody, non-silicone caulk around the joint between the shower pan and tile.

I use the bath fan, squeegee the shower and leave the enclosure door cracked to speed drying. Scrubbing the interior every so often doesn't hurt either. :D

GoldenFinch
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Re: Mold in caulk of shower

Post by GoldenFinch » Sat Jul 28, 2018 7:25 am

Oxy-Clean spray. Spray it on and leave it for an hour and rinse. :happy If it doesn’t work you probably have to recaulk. :|

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mrc
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Re: Mold in caulk of shower

Post by mrc » Sat Jul 28, 2018 7:30 am

Bengineer wrote:
Sat Jul 28, 2018 7:21 am
I use the bath fan, squeegee the shower and leave the enclosure door cracked to speed drying. Scrubbing the interior every so often doesn't hurt either. :D
That right there is necessary. Wet+time=mold
If it’s not long term it’s small talk

timemoveson
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Re: Mold in caulk of shower

Post by timemoveson » Sat Jul 28, 2018 7:45 am

mrc wrote:
Sat Jul 28, 2018 6:37 am
Bleach. The tricky part is getting it to stick long enough to work. A couple hours. I've used a baking soda/bleach paste with good results. You'll also want to correct the conditions that enable the mold to grow. If you remove the old caulk (not easy) and reapply, the new caulk will eventually mold unless you address the favorable conditions.
This worked extremely well for me. Just leave the paste on all day. It dries out on it's own, and you essentially rinse it away at the end. 95% improvement. Not perfect, but very good.

lws6772
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Re: Mold in caulk of shower

Post by lws6772 » Sat Jul 28, 2018 9:45 am

I have taken an old toothbrush and used it to work several applications of bleach into the affected areas. This has limited results and I usually only do it when time is a factor and for smaller spots. For bigger areas, caulk removal, cleaning and recaulking seems to be best.

snowman
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Re: Mold in caulk of shower

Post by snowman » Sat Jul 28, 2018 9:55 am

This is what works 99% of the time, in my experience:

https://www.homedepot.com/p/ZEP-32-oz-M ... /100619250

Just spray on, and you can watch the mold disappear in about 3-5 minutes. Then just spray down with water. Have the bathroom fan on as the fumes are very strong.

If some mold remains, spray again (when dry), wait 5 minutes, and brush off with your cleaning brush. It will come right off.

rantk81
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Re: Mold in caulk of shower

Post by rantk81 » Sat Jul 28, 2018 9:58 am

I've had good luck with making a paste out of baking soda and bleach, and spreading it on the caulk, and letting it sit. I think it contacts better than with cotton balls. Be careful that the bleach won't damage any of the materials you have (like expensive tiles, marble, etc, if applicable.)

retiredjg
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Re: Mold in caulk of shower

Post by retiredjg » Sat Jul 28, 2018 10:14 am

If the mold is ON the caulk, things like bleach or oxy-clean might work.

It didn't work for me because the mold or mold stain was IN the caulk. For that problem, I don't see any solution other than digging it out and recaulking with mold resistant caulk.

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cheese_breath
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Re: Mold in caulk of shower

Post by cheese_breath » Sat Jul 28, 2018 10:15 am

Let's verify OP is referring to a tile shower. If he tries these solutions on acrylic wall covers such as Re-Bath they'll ruin the finish.
The surest way to know the future is when it becomes the past.

Housedoc
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Re: Mold in caulk of shower

Post by Housedoc » Sat Jul 28, 2018 10:26 am

Pick up a set of inexpensive caulk removal and spread tools. Remove caulk, clean area good, then wipe with rubbing alcohol. After that dries, place painters tape about 3/16 away on each side of joint. Caulk and spread with tool or wet finger. After 5 min, peel tape away. Let dry 24hrs. Use a kitchen and bath silicone.

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AAA
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Re: Mold in caulk of shower

Post by AAA » Sat Jul 28, 2018 11:30 am

I spray a mixture of one part water and one part bleach onto the shower walls and the tub caulking, open the window and close the door. I wait 20 minutes or so and then wash it all down with the shower head. It seems to do a good job of removing mold from the tile grout and tub caulking. I may have also sometimes done a little brushing of the grout. I'm not sure why bleach isn't working for you.

BashDash
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Re: Mold in caulk of shower

Post by BashDash » Sat Jul 28, 2018 11:39 am

Op here. Thanks for all the detailed replies. I think retiredjg has the answer. I think the mold is on the inside of the caulk. Otherwise I think my method probably would have worked. Looks like a recaulking no is in my future.

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shmidds
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Re: Mold in caulk of shower

Post by shmidds » Sat Jul 28, 2018 12:58 pm

The best tip and results I've had applying new caulk is to put a little denatured alcohol into a small misting bottle and spray the caulk before smoothing. This makes for a clean bead, easy clean up, and no sticky mess.

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mrc
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Re: Mold in caulk of shower

Post by mrc » Sat Jul 28, 2018 1:01 pm

snowman wrote:
Sat Jul 28, 2018 9:55 am
This is what works 99% of the time, in my experience:

https://www.homedepot.com/p/ZEP-32-oz-M ... /100619250

Just spray on, and you can watch the mold disappear in about 3-5 minutes. Then just spray down with water. Have the bathroom fan on as the fumes are very strong.

If some mold remains, spray again (when dry), wait 5 minutes, and brush off with your cleaning brush. It will come right off.
For the record, this Zep product is sodium hypochlorite, i.e., bleach. :sharebeer
If it’s not long term it’s small talk

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Sandtrap
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Re: Mold in caulk of shower

Post by Sandtrap » Sat Jul 28, 2018 1:04 pm

BashDash wrote:
Sat Jul 28, 2018 6:12 am
Hi all, novice DIYer here. Have some mold in caulk of shower and am trying to remove without removing caulk and then recaulking. I realize this may have to be done but am trying to avoid. I read on some DIY blogs that you can soak some cotton balls in bleach/water solution and then place on the caulk for two or three hours. I tried this and left it overnight but there is no noticeable effect. Before I try again I figured I would check in here. Thanks!!!
Latex or Latex - Acrylic, or Latex - Sillicon "blend" caulking is more prone to this than Pure Silicone based caulking.
You can remove mold with bleach. To recaulk, clean remove all old caulking scrape and clean and dry, then recaulk. Cut the tube tip 90 degrees. Hold a steady bead and do not touch it with our fingers or tool to smooth it out. Get it smooth the first time. The "pros" do not touch the bead after running it because they don't need to.
j

magazinewriter
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Re: Mold in caulk of shower

Post by magazinewriter » Sat Jul 28, 2018 8:55 pm

Housedoc wrote:
Sat Jul 28, 2018 10:26 am
Pick up a set of inexpensive caulk removal and spread tools. Remove caulk, clean area good, then wipe with rubbing alcohol. After that dries, place painters tape about 3/16 away on each side of joint. Caulk and spread with tool or wet finger. After 5 min, peel tape away. Let dry 24hrs. Use a kitchen and bath silicone.
+1

I just did this a few months ago for my master bath bathtub. Real pain to do it. I used a screwdriver to remove the old caulk. Using the blue painter’s tape on the recauking really made it look nice and neat. Now, every time I get out of the shower I use an old facecloth to dry the caulked area. Only takes a minute and I hope it will help keep it mold free.

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