Just in case anyone can help, I think it's worth asking if anyone else
has experienced what iron sulphate can wreak on a wooden floor!

I was in the kitchen yesterday transferring the contents of a packet of
iron sulphate powder to an old biscuit tin (the tin's good for giving
the "powder" a good long shake and breaking down the lumps), but while
putting the cardboard box into the rubbish bin a few of grains fell out
of the lining of the packet and onto the floor.

I now realize I should have quickly sucked these up with a vacuum
cleaner. But unfortunately that's not what I did. I reached for a damp
cloth and wiped the grains up.

Several hours later I saw that there was a dark splodge of about 2 feet
square in the middle of the floor! Some of the grains must have
instantly dissolved in the dampness of the cloth, producing an acidic
solution which I then rubbed around the patch to clear up remaining
grains.

Went online and found that the powder that rhododendrons so adore, is
also used professionally to stain wooden floors a dark greyish shade!

The only remedies I've been able to find online have been:

- apply white vinegar, wait five minutes, rub, then rinse off

- apply lemon juice, wait five minutes, rub, then rinse off

- apply oxalic acid (!), wait, rub, and rinse

- and if these don't work, then resign yourself to removing the varnish
and sanding the wood.

Apparently iron sulphate will penetrate through varnish!


So far, I've applied white vinegar but there's been no miraculous
removal of the grey stains, unfortunately. Still to try the lemon
juice. Don't know whether it's worth purchasing some oxalic acid. May
just go for the misery of sanding and revarnishing.


Does anyone know of any other remedy for this problem - other than never
letting iron sulphate loose inside the house again. The only reason it
was indoors is that a whole packet can turns to a solid lump if kept in
an outdoor shed (in the damp).


Eddy.