I'm looking to use cork as internal wall insulation, it's cheaper then wood fibre. As cork looks nice I'm thinking of leaving it exposed and unsealed. This will mean using an adhesive to fix it to the walls and possibly some galvanized nails to improve stability. The supplier recommends using cold mastic to fix the boards to the wall but I'm wondering how green this stuff is. Auro produce a latex based adhesive which is expensive but may do the job.

What experience/advice have people got on green adhesives. One major benefit I can see is no drilling into my walls and improved air tightness/cold bridging.