Preservation

During listing the condition of the plans was assessed using the National Preservation Office’s Preservation Assessment Survey criteria. This means the plans are described as being in good, fair, poor or unusable condition and numbered 1-4 accordingly. Those plans assessed as 3 or 4 were then singled out for more intensive conservation treatment.

Hundreds of the plans were in very poor condition, and required conservation work before they could be used.

A bundle of plans on tracing paper before treatment.

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This tracing paper is made by coating thin paper with linseed oil. The oil has aged, turning the paper brown and making it very brittle.

The plans have been carefully separated.

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Gentle localised heat is used to ease out the creases.
The spatula has a thermostat so it doesn’t get too hot and damage the plan.

 

Special tissue paper is used to strengthen the plan.
The glue on the tissue paper is activated by the heat of the laminating press.

The finished plan

[BC/S1/0]

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A blueprint before treatment showing tears and missing areas.

The plan is relaxed with moisture, flattened and the missing areas filled with Japanese paper and starch paste.

The finished blueprint.

[BC/S1/7948]

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