Cork insulation?

Specific Inspection Topics Inspecting HVAC Systems
1

Home built about 1950. Looks like cork insulation on air ducts. Take a look at the image. I have never seen this. Any information?

cork1.jpg
cork1.jpg1175×1211 336 KB

2

Cork was an exceptionable insulation back in the day mostly used on Chilled water lines industrial type. I don’t recall ever observing it on supply air duct. As long as it was in tac I don’t see a problem. Yours looks pretty rough

3

Thanks. You are correct. This home had a chilled water/boiler system when first built. I found information about Armstrong cork on the net. Here is an old booklet showing cork being used on air ducts.

Armstrong’s insulation and interior finishes ; corkboard, cork covering, di corkboard, Temlok, Temok deluxe, Vibracork. : Armstrong Cork Company : Free Download, Borrow, and Streaming : Internet Archive