What kind of mold is this?

April 17, 2008 7:50 PM

This is mold, obviously; but why is it growing only on the seams of these blocks of wood?

I have hundreds of 'woodblocks' in my storage room in the basement; these are flat planks of wood carved for woodblock printmaking. Most of them are solid planks, but around 10% of them have a plywood core, with hardwood faces bonded.

Mold has now started to grow on these blocks, but only on the ones with plywood cores, and only on the seams of the plywood. Pics: 1 2 3

I guess the solution is straightforward: wipe them down, wash the edges with a disinfectant, and then seal/varnish/etc. But what's going on? Every plywood block in the storage room is being attacked this way, even those from different years/makers/types/etc.

posted by woodblock100 to home & garden (6 comments total)

Whatever it iw, it appears to be related to the glue, not the wood.

I'm not so sure that's really mold. It looks to me like the glue is breaking down somehow. Repeated changes in humidity might do that, especially if it's old.

Unless the plywood begins to feel soft or flexible, I would say it isn't really a cause for concern. Just brush it off.
posted by Class Goat at 8:00 PM on April 17

my guess (if it is mold. Class Goat might be right), is that the wood is treated with a fungicide, and the glue holding the layers together is not.
posted by ArgentCorvid at 8:07 PM on April 17

The seams are just porous enough to give the hyphae of the mold an ideal habitat.
posted by kuujjuarapik at 8:44 PM on April 17

The parts may be bonded together with a glue that has an organic base and the base includes some mould spores which, given the ideal conditions (apparently, your basement), will sprout. I have seen this before.
posted by dg at 10:08 PM on April 17

Shiitake?
posted by watercarrier at 3:42 AM on April 18

I'm not so sure that's really mold.

Well, it certainly smells like it ...

Here's the curious thing, though. These blocks were all put into that storage room at the same time, a few years ago. No mold (visible) at that time. But the amount of mold now varies considerably on all the plywood blocks - newer ones have no mold, the oldest ones are covered with it, even though they have all been in there the same length of time! The photo I showed is about the middle of the range.

So it seems the glue (or whatever) that it is 'food' for this stuff is resistant at first, but breaks down over time, I guess with exposure to air, etc. ...
posted by woodblock100 at 4:35 PM on April 18