Mystery material applied to floor joists

[Joseph D. Skrypka]

Does anyone have any idea what this material is and what its intended use is? It has been applied to a few floor joists in the basement of a 60ish year old house. It is hard and brittle, originally brushed on. Where the bubbles have burst, a powdery substance (gray in color) is revealed. You can brush off this substance - it's not adhering to the surface.

And yes, the knob and tube wiring is live......

Thanks to all in advance.

[Joseph D. Skrypka]

I should clarify..... the powdery substance brushes off, but the orange substance adheres to the surface.

[Roy D. Cooke, Sr]

do not know what it is but I do not think it was brushed on as there is none on the board above and none on below.
I think it is some thing that grew on the wood and now has dried out .
Will look more after supper .
Roy Cooke

[Doug Edwards]

I have seen this material once before, years ago. I seem to remember it being some kind of sealant but can not remember the name of it. The time I saw it, it had been used by the homeowner to cover a floor that I suspected was not level. I remember too thinking "What a butt ugly floor color." Owner thought it was great. go figure.

[Darrell B. Hadler]

For one thing I'd guess the home a lot older than 60ish if it had knob and tube wiring??? 30s or 40s at the latest in our area. And just for another twist on why the beam was sealed with that orange stuff...a little while ago I inspected an acreage that had quite a noticeable, kinda chemical odor to it...couldn't put my finger on it till I got to the wood basement and saw the very large main beam of the home covered in plastic and taped up with duct tape? My brain was really doing laps then:

Turned out whoever built the home, used some old railway tie wood, that was soaked in oil and creosote pits to preservative it. It will last forever...but so does that stink it can't be covered up or masked, it just keeps emitting that smell indefinitely. At first I thought it was just the damp wood basement....but that pungent smell....I new I'd smelled it before, but just not in a home!

Did a bit of research on the inter-net...apparently not a lot of studies done on the effects to the respiratory/nervous system by breathing in the vapors, over an extended number of years, but lots on how fast it kills fish in lakes and water. Needless to say buyer decided the home had too many strikes against it already, and that was just one more nail in the coffin.

Not saying this is what your home had...just food for thought. Just when you think youv'e seen it all..........