Removing black adhesive under insulation.

[pianoderby]

I recently started stripping the interior on my S3 coupe. Underneath the carpet and insulation there is a thick layer of back adhesive that is quite determined to stay stuck on the fiberglass shell. Assuming this is a normal thing to find beneath the insulation, is there a tried and true method for removing all of this so I can get down to the bare shell?
Here is a photo of the offending substance.

Brian

[mikealdren]

None on my cars but there was some glue. I removed this and underseal by scraping off as much as possible and then cleaned the rest off with gentle use of a wire brush on an angle grinder (with ear defenders, goggles and a dust mask of course).

[TrevorJones]

only method that worked for me was to attack it with a power wire brush (fine wire) and once only the black bitumen is left wipe over with petrol on a rag.

[jono]

...just be aware that bitumen underseal and adhesives from this era can contain asbestos fibres

[69S4]

...just be aware that bitumen underseal and adhesives from this era can contain asbestos fibres

Blimey! And I thought it was a big enough health hazard just driving them

[DavidP]

Blasting with crushed glass works really well.