Palazzo Valmarana

Conservation condition: sheet XVII4



Palazzo Valmarana

Enlarge image Enlarge image

Detail of Sheet XVII/4r

Andrea Palladio (c.1566)

RIBA Library Drawings Collection


Palazzo Valmrarana

Enlarge image Enlarge image

Detail of sheet XVII/4v

Attributed to Inigo Jones (c.1610)

RIBA Library Drawings Collection

Date of drawing: circa 1560

Laid lines: 28mm apart

Watermarks: anchor and a six-pointed star and the letters BA

Weight of paper: very thin, lightly sized

Conservation condition of the drawing: fair; heavy embedded creases, ink deterioration, losses, ingrained dirt

The thinness of the drawing paper has made it very vulnerable to creasing, and there is a build up of ingrained dirt, undulations and extensive cockling. The sheet has been trimmed in the right-hand corner.

The drawings on the back are thought to be sketches by Inigo Jones of Palazzo Valmarama .These sketches have caused most of the damage to the paper because of the dark iron gall ink.

Deterioration happens in stages:

  • fluorescence, visible under UV, of the support around the area of ink application
  • brown feathering of the ink at the edges
  • bleeding into the support; ink can offset onto other papers
  • total degradation can lead to physical losses as the support (paper or parchment) becomes increasingly fragile

Iron gall ink oxidises quickly in the open air and goes from a ferrous state to a ferric state. As a result the paper or support decline in their natural properties.

Because the ink consists of iron and other transition ions copper and zinc, they deteriorate. The chemical reactions between the gallic acid and the iron sulphate can produce sulphuric acid and an excess of iron sulphate. This becomes worse with fluctuating environmental conditions.

The iron gall ink used by Palladio on the front of the sheet is light brown. The fading of iron gall ink is due to many factors, including original ink composition, oxidation and pollution, light degradation and humidity levels. In the sketches by Inigo Jones the ink remains dark.