Tiny black sand falling from old wooden ceiling - what is it?
May 10, 2016 3:08 PM   Subscribe

I've worked in a couple of old wooden buildings in downtown Toronto. The interiors look like this, more or less. Little hard black bits occasionally fall from the ceiling, about the size of sand grains. They are hard. Sometimes they land in my lunch. Any idea what they might be? I'm guessing some kind of preservative, maybe creosote?
posted by clawsoon to Grab Bag (14 answers total) 1 user marked this as a favorite
 
i would assume it's probably termite frass/poop. (sorry about your lunch... but... probably.)
posted by koroshiya at 3:12 PM on May 10, 2016 [7 favorites]


It's not creosote as that penetrates the wood so you wouldn't have that blonde colour.
posted by Mitheral at 3:21 PM on May 10, 2016


Having owned an old house, dust, dirt & other crap (literally crap insect & rodent) build up in the ceilings. As the wood shrinks opening gaps & the now dried & crumbly "dust" falls through. I tore my kitchen ceiling down in a 140 year old house & gagged at what I found up there.

If the wood panels above are the actual floor of the room above I'm seconding termite poop. ON the plus size it's just chewed up wood, oh it looks like a tiny foot ball and very interestingly six sided with sort of dimples so if you can get a good look at it you can know for sure pretty easily. Mi
posted by wwax at 3:29 PM on May 10, 2016


Could also be sandblasting residue, from when they cleaned off the old-style fireproofing (if the building is now sprinklered). Does the wood have an unusually prominent grain pattern that's, for lack of a better term, 3D?
posted by aramaic at 3:33 PM on May 10, 2016 [2 favorites]


Could be coal dust, depending on the building age.
posted by Chrysostom at 3:40 PM on May 10, 2016


Coal dust and little bits of coke from years of fires is a good guess. I've noticed that bitumen/pitch seems to harden and break up after many decades, too; that's another source of gritty black stuff.
posted by pipeski at 3:48 PM on May 10, 2016


I worked in a similar building and my vote is sandblasting leftovers. Modern folks don't actually like the old warehouse look, they just think they do, and so often blast that cruddy old white paint off first thing when revamping old buildings.
posted by Nosmot at 5:06 PM on May 10, 2016 [2 favorites]


Could be anything. Do you know how many times anyone has cleaned in between the the cracks of those tongue-and-groove boards, since they were installed a century or more ago? Zero. Zero times.

If you pulled apart that ceiling, you would find that every part of every one of those boards that can't be seen from below is absolutely filthy. I promise you this. Sometimes when the building shifts around, which old buildings do, bits of filth can come loose and fall out.

It's probably a mixture of dust, wood resin, insect and small-mammal droppings, things that have spilled on (from above) and splashed on (from below) the boards over the years, bird shit, tobacco smoke, possibly some paint and/or oil, insulation, and yeah maybe some termite frass and/or sandblaster sand if applicable.

I've pulled apart more than a few old ceilings and they're always pretty gnarly once you start seeing the hidden bits. Same goes for walls and floors. Over time, filth finds a way.
posted by Anticipation Of A New Lover's Arrival, The at 5:16 PM on May 10, 2016


I'll clarify that the bits are very hard, and the surfaces remind me of glass or mica or long-hardened resin. The edges are sharp, unlike what I'm seeing in Google for termite poop. Much less regular, too.

Ceiling == floor, as far as I can tell; our ceiling is floor boards sitting on top of the giant wooden joists.

Yes, aramaic, the grain pattern (at least on the columns that I'm close enough to examine, since the ceiling is 12 or 16 feet above me) is very "3D".

If it was sandblasting of the old fireproofing, does anybody have pictures or descriptions of what the old fireproofing might have looked like/was made of?

Thanks!
posted by clawsoon at 5:26 PM on May 10, 2016


clawsoon: "I'll clarify that the bits are very hard, and the surfaces remind me of glass or mica or long-hardened resin. The edges are sharp, unlike what I'm seeing in Google for termite poop. Much less regular, too."

That is a pretty fair description of sandblasting media. Note that it's not necessarily from sandblasting the building; it could also be working its way through the floor/ceiling from any sandblasting that was done on the floor above.
posted by Mitheral at 5:37 PM on May 10, 2016 [3 favorites]


Yep, Mitheral, this looks at lot like it. Thanks!
posted by clawsoon at 5:42 PM on May 10, 2016


... the surfaces remind me of glass or mica or long-hardened resin.

My guess is it's bits of the undersides of asphalt shingles.
posted by jamjam at 6:23 PM on May 10, 2016


Vermiculite?
posted by The Toad at 7:28 PM on May 10, 2016 [1 favorite]


The roof is six floors above us, so asphalt shingles seem unlikely. And asbestos is generally greyish brown, besides being something that I assume would've been a big deal in a multi-million dollar downtown building project. So I'm going with sandblasting residue as the most likely.
posted by clawsoon at 11:07 AM on May 11, 2016


« Older Help me pamper myself   |   Short relationship and he asked for space to think... Newer »
This thread is closed to new comments.