QUARTERLY

NUMBER SIXTEEN–1961

THIS ISSUE OF THE 'QUARTERLY' is devoted to
notes on some of the many works, both in the permanent collection and on long term loan to the Gallery, which have passed through our Conservation Studio.
  The Conservation Department is under the charge of Mr L. C. Lloyd, and his notes accompany the illustrations.

THE CONSERVATION OF WORKS OF ART is made
rather more trying in this South Pacific latitude by the sudden temperature changes. The relative humidity ranges from 23 per cent to 86 per cent over the year.
  At times it is possible to see the condensation of the saturated aqueous vapour on the paintings – in particular, those upon canvas with stretcher, when the surface will be seen to be covered with droplets of moisture.
  The canvas having absorbed a great deal will appear limp and sagging. The only complete remedy is, of course, air conditioning.
In the meantime we are gradually working our way through the collection and attaching all suitable paintings to a new, rigid support of compressed fibre-board by means of a wax

resin mixture. With a varnish film on the paint surface, this treatment prevents absorption of moisture both from the front and rear and consequently its limp appearance –which of course tightens again as soon as conditions become dryer.
  The subjection of the paint surface to the tension of such a variable support as canvas is bound to become evident sooner or later. The paint attachment becomes weakened and begins to cup and flake, hence the present treatment of isolating the canvas from moisture permeability.
  With these humid conditions pictures on paper are prone to a brown mould (or foxing) which grows on these substances which, being hygroscopic, present a suitable medium for the fungus cultures. This brown mould has been proved to germinate above 75 per cent relative humidity – a condition frequently experienced in Auckland. Here again air conditioning would help. However, the Gallery has installed a sterilisation chamber and the whole of the collection is being subjected to routine treatment in order that the more radical treatment of chemical bleaching, and its consequent dangers, will be avoided.

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