This is not what you want to see when you take apart any frame, let alone a drawing by L.S. Lowry. Self adhesive tapes such as seen here (yellow/brown masking tape and parcel tape) should not be used inside framing, and should NEVER come into contact with the art. You can see in the second photo where the adhesive in the parcel tape has dried out and left a nasty residue.
These are some of the frames I have been working on for the last few weeks. The watercolours are by Nigel Ashcroft for an exhibition at John Noott Galleries in Broadway, www.john-noott.com