caulk

[The Data Rat]

What did I do wrong? I removed all of the caulk from around the tub, even used a solvent to remove minute traces, and let it dry for three days before applying new caulk. I filled the tub with water, recaulked using siliconized mildew resistant caulk and let that cure for a week. I left the exhaust fan on the whole 10 days. Three months later, there is black mildew IN the caulk, not on top where I can scrub it off.

I don't see any evidence of moisture (loose tiles, or soft spots when I bang on the walls. This is the third time I have recaulked in 2 years. I thought I had covered every aspect of keeping the area dry and ventilated while doing the job. I was told to fill the tub with water because it sinks ever so slightly when full, causing a crack in the caulk that would let moisture in.

Any more ideas? I have a white tub, white ceramic tile walls, and a white ceramic tile floor. (Whoever thought up this creative color scheme must be a glutton for punishment!

Thanks

[Vox Humana]

The key word is "resistant." That isn't the same as 'mildew proof." Don't blame yourself, it sounds like you did all you could. I would use some chlorine bleach on it. It needs to stay wet for about an hour. In vertical areas, apply some plastic wrap over the wet area to prevent evaporation and limit run-off. You will probably be committed to periodic treatments. I use Clorox in a spray bottle. You should open a window and/or turn on the ventilating fan and close the door in the bathroom. Don't mix other household cleaners with the bleach and avoid breathing the fumes. After about an hour, rinse the surfaces well with water and dry. If the discoloration doesn't go away, repeat. Make sure to use rubber gloves and protective eyewear when working with bleach.

[The Data Rat]

[Vox Humana]

Yes.

[570-622-6441]

Just a note: bleach needs to be dilute to kill mold spores. Straight bleach will irritate the wall of the spore, it will harden, and not kill the spore. Spores will allow dilute bleach to enter, and then kill them.

: > I don't see any evidence of moisture (loose tiles, or soft spots when I : bang : > on the walls. This is the third time I have recaulked in 2 years. I : > thought I had covered every aspect of keeping the area dry and ventilated : > while doing the job. I was told to fill the tub with water because it : sinks : > ever so slightly when full, causing a crack in the caulk that would let : > moisture in. : >

: > Any more ideas? I have a white tub, white ceramic tile walls, and a white : > ceramic tile floor. (Whoever thought up this creative color scheme must : be : > a glutton for punishment! : >

: : The key word is "resistant." That isn't the same as 'mildew proof." Don't : blame yourself, it sounds like you did all you could. I would use some : chlorine bleach on it. It needs to stay wet for about an hour. In vertical : areas, apply some plastic wrap over the wet area to prevent evaporation and : limit run-off. You will probably be committed to periodic treatments. I : use Clorox in a spray bottle. You should open a window and/or turn on the : ventilating fan and close the door in the bathroom. Don't mix other : household cleaners with the bleach and avoid breathing the fumes. After : about an hour, rinse the surfaces well with water and dry. If the : discoloration doesn't go away, repeat. Make sure to use rubber gloves and : protective eyewear when working with bleach. : :

[Lloyd Randall]

Single atoms of oxygen, released as bleach breaks down, destroy spores. Concentrated bleach is too alkaline to break down very well.

Lab tests show bleach kills some kinds of household germs, but this doesn't work for all types. It's probably the alkalinity of bleach that kills some germs. Other germs tolerate alkalinity.

The citrus-packing industry has found that baking soda makes bleach kill germs a lot better. It brings down the alkalinity to improve the bleaching.

[Sweep]

"DOMESTOS kills 99% of all known germs!"

[570-622-6441]

Lloyd,

Perhaps you were thinking of hydrogen peroxide, H2O2, which is water, H2O, with a loosely attached Oxygen molecule

Bleach is Sodium Hypochlorate, Salt water with an extra chlorine molecule that interacts with dang near any organic that gets in it's way.

Almighty Bucketman

: Single atoms of oxygen, released as bleach breaks down, destroy spores. : Concentrated bleach is too alkaline to break down very well. : : Lab tests show bleach kills some kinds of household germs, but this : doesn't work for all types. It's probably the alkalinity of bleach that : kills some germs. Other germs tolerate alkalinity. : : The citrus-packing industry has found that baking soda makes bleach kill : germs a lot better. It brings down the alkalinity to improve the : bleaching. : : -- : Best Regards, : Lloyd

[Lloyd Randall]

Under what conditions did they test it? When they tested chlorine bleach, they used a limited exposure time, as would be the case with normal cleaning.

Domestos has sodium hydroxide, doesn't it? That would be even more caustic than concentrated bleach, but would it kill spores?

When spores must be killed, the EPA recommends adding vinegar to bleach, but that could be deadly unless instructions are followed carefully. Soda is safer.

[Lloyd Randall]

I'm not familiar with Sodium Hypochlorate. Salt is NaCl, and a Chlorine molecule is Cl2. Is Sodium Hypochlorate NaCl3?

Sodium Hypochlorite is NaOCl. The cheap way to make it is by the electrolysis of salt water with a membrane to add an oxygen molecule to salt.

Sodium Hypochlorite is a source of oxygen for bleaching, but normally it must produce hypochlorous acid (HOCl) in order to release oxygen. The lower the pH, the more HOCl and the faster the bleaching. That leaves HCl and NaOH which produce salt, and there are electrical devices that can turn the salt back into bleach in your pool.

It's possible for Sodium Hypochlorite to release Chlorine, which is usually undesirable. In a pool, if the pH is too low, there will be enough Chlorine to redden eyes.

Chlorine in pools is often blamed for the deterioration of swim suits, but they deteriorate the same way in pools that use chlorine-free bleach. It's the Oxygen.

[Sweep]

Hi Lloyd. I don't know. its what they used to say on the TV advert, then they would finish it by saying ...dead :)

I don't have a bottle here but probably the original would have sodium hydroxide in but they have other ones now with different bleach in