There used to be a soap dish in what is now a hole in
this shower wall.The dark color inside the hole is mold growing inside
the wall. The duct tape is to make the shower usable while wating for
ClO2 will work on the exposed mold but not
on mold elsewhere behind the tile. The tile needs to be removed
to repair this problem.
This is the corner of a damp basement where the mold
is growing uncontrolled.
ClO2 really works on this problem.
Generally when this kind of problem is found, there is mold growing
elsewhere as well. It may not be black but it is almost there. Treat
the enitre area as if you knew it had mold and the problem will be
Uncontrolled black mold growing on dry wall. In order
to remediate this room, the involved drywall will have to be removed
because the mold fungus has completely involved the drywall. There
is no doubt mold growing inside the wall as well. Removing the effected
drywall plus another foot will expose the problem and make it treatable
with OdorXit ClO2. Of course the water problem
needs to be resolved.