Palazzo Valmarana

Conservation of iron gall ink


The Queen's house

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Chimneypiece and overmantel, Queen's House, Greenwich

Inigo Jones (c.1637)

RIBA Library Drawings Collection


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Queen's House drawing under magnification

Inigo Jones (c.1637)

RIBA Library Drawings Collection

On sheet XVII/4 the bleeding from the back sketches to the front of the paper partially obscures the lighter ink drawing by Palladio. The sketches, thought to be by Inigo Jones, have caused fractures and losses in the paper where the iron gall ink has remained dark and the ink has been liberally applied.

The damage caused by iron gall ink can be directly related to both the amount of size applied to the sheet and the amount of ink applied. Insufficient size gives insufficient protection. Areas of dark ink can make the paper fracture as is clearly shown in Inigo Jones' design for a chimneypiece and overmantel at the Queen's House. The deterioration of iron gall ink causes a low pH in the paper.

The treatment of iron gall ink

Most analysis and proposed treatments for iron gall ink have been in relation to documents rather than drawings.

Suggested treatments for iron gall ink found in conservation literature include

  • stabilisation of the cellulose using calcium phytate
  • climate control with enclosed storage, a preventative method
  • deacidification with barium hydroxide
  • full lining on the reverse of the paper with Japanese tissue
  • local repair with Japanese tissue

The majority of the Palladio drawings with the least vulnerable iron gall ink or paper were able to withstand humidification. The treatment was closely controlled to prevent the bleeding and migration of the ink. Further aqueous methods were not considered as they might have caused further risk of bleeding and migration.  

Sheet XVII/4 was consolidated by raising the pH from the verso using a local support repair. Where there is an image on both sides full lining is not preferred. In this case it was not necessary as the damage and loss was not extensive and affected only one area. Local repairs using Japanese paper were applied to the reverse of the sheet as it was the least intrusive method. 

Sheet XVII/4 was inlaid onto a new support paper and mounted using a deep overthrow mount prior to framing for Palladio500.