Chelating agents

re: chelating agents

The AIC paper conservation catalog, ch.16, washing, section 16.3.6,
chelating agents,  explains that EDTA can be used to decolorise or
solubilize metallic stains, esp. Iron in paper.

(They are also used in paper manufacture.: J.R.Hart, Chelating agents in
the pulp and paper industry, TAPPI journal no.64 ,1981)

Helen Burgess, Practical considerations for conservation bleaching IIC
(Canadian Conservation Institute) CG Vol 13 or, Helen Burgess, "The use
of chelating agents in conservation treatments" in The Paper
Conservator, Vol 15, as " (concentrating on EDTA) It has a large
bibliography.

There is apparently an article on Rust Removal using Vitamin C, by D
Baynes Cope, Society of Archivists


    **** Moderator's comments:   Mark wrote back to add:

    It appears the Baynes-Cope rust for removing rust from paper using
    vitamin C was never published, but it involves using vitamin C to
    reduce iron+++ to iron++ and then dissolving the iron++ in
    hydrochloric acid.

    Dissolve 1g ascorbic acid in 100cc of 10% w/v HCl. Apply to rust
    stain. When rust stain disappears, wash and deacidify. It helps if
    you keep it warm--place a beaker of water at 45 deg C on the area
    under treatment. Alternatively, pile on dry ascorbic acid and
    saturate with 2M HCl. This works but may be too drastic for your
    object

Mark Clarke

                                  ***
                  Conservation DistList Instance 8:78
                 Distributed: Thursday, March 23, 1995
                        Message Id: cdl-8-78-006
                                  ***