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Mold? Fungus? Anyone know what this stuff is? Answered

I have a small fire safe I use for storing documents and backup drives.  Yesterday I opened it to find this stuff growing on the inside.  It has a crunchy outer texture that crumbles if you touch it, and a bit of liquid inside.  It wasn't there two months ago when I last opened the safe, and I've never had problems with it in the year I've owned the safe.  I have moisture absorbers inside, and live in a dry climate.  Any ideas what this could be, and whether I can just wipe it down with cleaner or need to take stronger measure?  Thanks.



Best Answer 2 years ago

Definately corrosion as evident by the paint bubbles.
Brown means rust.
I assume the paint was slightly damaged and your moisture absorbers produce a slightly acidic climate in your safe.
Best to just use silica gel in enclosed spaces.

Clean the loos paintwork with a wire brush.
Get some good paint with primer included and give the inside a new coat after properly cleaning the scratched remains with acetone or alcohol.
For the paint I suggest to ask for a hard wearing one like used for machines and farm equippment.


2 years ago

Probably touched it with a BARE FINGER !

IF it was organic it might be busy feeding on the iron atoms in your hemoglobin (blood cells) right now, How do you feel ??


Answer 2 years ago

And the paint bumps close to the, well focused, orange blight on your first picture suggests more is forming under the paint ready to burst through.

Rubber gloves and move it out of your living area is a good safety precaution..


2 years ago

It looks like rust to me also. Probably from the latex paint which is probably water based. Latex paint works on walls because after it skins over it continues to loose moisture into the wall through the back side. If that backside is something like metal then the moisture can;t escape, the paint can't breath. So essentially the paint seals a layer of moisture behind it in contact with the metal, hence rust. An oil base paint would not cause this but then oil paint smells for a long time and does release fumes that could effect the contents of the safe.

What to do? First you might complain to the manufacturer. Depending on how many complaints they have had they might have a fix already.

If they are not interested in the problem there are a few options.

Just heating up the safe would probably not cure the problem but it could help. A small electric heater left inside for a while might cure the paint, but probably not.

To really fix it you should strip out the old paint and then coat it with a couple of light coats of a rustoleium type spray paint to seal the metal.

However if the moisture is actually inside the walls of the safe it will most likely continue to rust until it is all dried out. You might need to leave it open for a few months to dry out.

Jack A Lopez

2 years ago

To me it looks like rust.


I mean iron(iii) oxides, totally inorganic. Also I suspect there is a source of moisture somewhere nearby, in spite of what you write about using moisture absorbers and living in a dry climate.

By the way, the material often used in the walls of these fire safes is this stuff called, "gypsum"


It is the same material used to make "drywall",


for the same reason: it is inexpensive, and offers good fire resistance, by virtue of all the water locked up in its crystal structure.

But you know, drywall really is dry, at ordinary temperatures. At 100C (212 F) to 150 C (302 F) it will start steaming, but at room temperature, it should be totally dry.

So really I have no idea how those rust bunnies got into that spot on the wall of your safe.

If the safe is new, maybe it had a wet spot in it, like in the gypsum in the wall in one place. I mean that is speculation on my part. Just a wild guess.


2 years ago

Possibly a slime-mould, based purely on it being orange...

My thought would be to wipe it down with something corrosive, rinse off with water as hot as you can bear to handle, then dry it with a heat-gun.