Hi, I am wondering if anyone could please help identify the white powder substance that is appearing on the shelves on my shed?
I think it may be some type of acid? It appears to be eating away at the metal of my shelves. I have previously brushed the shelves down to clear this before but it has returned, so I suspect I may need to use some sort of cleaner?
There was a leak in the roof for a few months and some tools became rusty as a result. The leak has been sorted but I wonder if it could be related to the powder substance.
Hmm, this kind of stuff is usually a result of water acting as a solvent pulling salts and similar substances from a substrate and later evaporating, leaving the powder behind.
It is probably something that was used to treat the plywood or a combination of that with the zinc coating of the metal (zinc-sulfate?).
Edit: probably sodium-borate, as that seems to be prone to leaching from wood treated with it.
Just looks like water damage- if you really think it’s acid, scrub it up with a baking soda and water solution. Once it’s dry, you could seal with some paint or leftover stain.
Thank you both, great information. I plan to clean the shelves down over winter, I will try some baking soda, then give them a coat of whatever I have lying around to seal the wood.
