Insulation identification question

[Michael Thomas]

New to me, can anyone identify this material and/or comment on its flammability?

Thanks in advance as always.

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[Scott Patterson]

New to me, can anyone identify this material and/or comment on its flammability?

Thanks in advance as always.

Looks like an old hemp rug.

[Michael Thomas]

There is hundreds of square feet installed, not only the entire underside of the roof, but there's also a similar material under the insulation at the attic floor - I've never seen anything like it.

House was built in 1915 by the way, and there seems to been a major upgrade sometime in the 1950s.