Ask A Scientist General Science Archive

name         Kari
status       educator
age          30s

Question -   I have new polished-brass framed, frosted glass shower
doors.  I keep getting
a brown residue built up on them.  This residue does not come off with
bathroom
cleaner, nor iron out....However, it does come off with Clorox Bleach.
This residue does not occur on my other shower that consist of the same
type of acrylic, but has a shower curtain instead of doors.
We do have a "Culligan" water softener in which we use the "Red-Out" Salt
to help remove the iron ions.....
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The fact that the yukky gross brown stuff comes off with Clorox bleach is
almost a dead give away that what you have is MILDEW. Mildew breeds very
quickly and voraciously if any water collects, or even if there are periods
of high humidity. Mildew feeds off residual soap, which is almost always
there, and water. I would bet that you are collecting small amounts of water
under the shower door. The shower with the curtain will "dry out" much more
quickly than water under the shower door.

Sodium hypochlorite, of which Clorox is a commerial name, is the classic
"cure" for removing mildew stains from damp basement walls, and other damp
areas.

You can help by making sure that there is no standing water under the shower
door after each shower (which may be a pain if children use the shower). You
can also install a ceiling fan to help dry out the shower area (This may or
may not be easy or $$$ depending upon where the shower is located.) You can
also wash down the shower area weekly with bleach -- more frequently for the
first couple of weeks -- even if you do not see any staining. The weekly
application of bleach is usually sufficient to keep the mildew under control
once you get the upper hand.

Vince Calder
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