The tech service person assigned to this within 3M supplied the following information:
Thank you for your interest in 3M aerosol adhesives.
3M Spray Adhesive's: 77, Photo Mount, Vac-U-Mount and Spray Mount have been tested by the Rochester Institute of Technology, Image Permanence Institute for pH and Photographic Activity. They are all pH neutral in the dry adhesive film state and pass the Photographic Activity Test for both color and black and white photographs.
Those are the only two tests we are aware of that would indicate if a spray adhesive is suitable for mounting prints/photos. We should not reference "archival" but rather these tests.
If I can try to help in any other way, please let me know.
Robert ( B. Jay ) Inserra
3M Industrial Adhesives & Tapes Division
Technical Service - Aerosol & Cylinder Spray Adhesives
3M Center, Bldg. 230-2S-29
St. Paul, MN 55144-1000