Rubber cement

To my knowledge, there is no solvent for rubber cement, if you make the
cement from natural rubber. Hydrocarbon solvents and chlorinated
hydrocarbon solvents cause rubber particles to swell, but they do not
dissolve these particles. In the swollen state, you can emulsify the
mixture to get a uniformly fluid mixture we know as rubber cement.

This insolubility may not be the case with rubber cement made from
synthetic rubber. (However, one of the properties that makes rubber an
important material is its inertness. This inertness includes resistance
to chemical and solvents.)

As natural and (many) synthetic rubbers age, they oxidize and become
more inert and insoluble. Aging causes the rubber to become yellow, then
brown, then black. As the color gets darker, the rubber becomes more
inert. (You can see such stages of degradation if you use cellophane
tape. Historically, these tapes were a mixture of resin in rubber
cement. This is why "cello' tape changes in color when in contact with
paper. The rubber is degrading.)

Trying to physically remove this rubber cement from paper, or the backs
of photographs may result in the removal of the paper along with the
dark residue. If the residue is already black and there is no
discoloration of the photograph, do not do anything. The residue may no
longer be a source of degradation of the image.

Before doing any work on an original photograph, make a good replicate.

See:

    FELLER, R.L. and D.B. Encke (1982). "Stages in deterioration: the
    examples of rubber cement and transparent mending tape." In N.
    Brommelle and G. Thomson [eds.] Science and technology in the
    service of conservation, p.19-23. London: IIC.

Robert C. Morrison

                                  ***
                  Conservation DistList Instance 8:60
                Distributed: Thursday, February 2, 1995
                        Message Id: cdl-8-60-003
                                  ***