At a gig, a customer was embarrassed to have to use his smartphone as a cheat sheet. However, the gaffa tape used for this left some ugly craters in the varnish of the bass when it was removed.
Reusable adhesive pads, such as those offered for mounting things on car dashbioards, are less dangerous for the varnish of a double bass. These adhesive pads do not use glue, but a vacuum, and therefore leave no adhesive residue on the bass. Depending on the condition of the varnish, they are certainly not completely safe, but my tests on various instruments did not reveal any problems when removing these pads.
Manufacturer Fischer offers such vacuum pads with Velcro backing. The specified adhesive force per set is 5 kg.
