Making Plans

An up-close perspective of the original materials…

Hello from the Treasure House Conservation Workshop!  Before I describe the digitisation process we’re undertaking I thought it would be worth looking back to the pre-digital age and taking a brief look at the history of technical drawing reproduction and the physical nature of the plans.

Though they span six decades, the Cook Welton & Gemmell ships plans are relatively uniform in size, material and condition. These utilitarian working documents were created with durability in mind, and clearly the ones in our collection have been well used; the signs of wear and tear and surface dirt indicate they weren’t just master copies left sitting in a plan chest. Yet they have survived well with few suffering major tears or loss of information and little conservation treatment is required to prepare them for digitisation.

“Between 1905 and 1962 when the plans were created there were a great number of image-copying technologies in use.”

The ships plans are either hand drawn or reproduced by printing – and it can often be difficult to identify the particular process used or to tell hand-drawn from printed copies.

close up of plan 806
Original ink drawing or gel-litho reproduction? It can be difficult to tell.

Before computer aided design, architects, ship builders and any other industry relying on technical drawings would have had to produce multiple physical copies of their plans from a master copy, as needed. Employing a draughtsman to trace each copy by hand was relatively expensive and time consuming when multiple copies of each plan were needed for both use in the shipyard and as preservation copies to be filed away for future reference. So naturally, various methods to quickly, cheaply and accurately reproduce images were commercially developed. The plethora of different patented technologies and rival brand names can make identifying the exact nature of a plan difficult for today’s conservators and archivists.

Earlier methods used to reproduce technical drawings were ‘photo-reproductive’, using light-sensitive chemicals. Blue prints are a well known and common example of this sort of process. The later methods emerging in the early 20th century are known as ‘photo-mechanical’: these use dyes, inks or carbon to create the image, for example the carbon-based images produced by photocopiers.

Between 1905 and 1962 when the plans were created there were a great number of image-copying technologies in use. Processes commonly encountered in early to mid-twentieth century collections include diazotypes, CB prints, gel-lithographs and later on, electrostatic copying. Different support materials, inks, dyes and chemicals present a variety of preservation challenges, and some formats are more permanent than others. Some plans can damage others if they are stored together, some are suitable for display and some are not, so it is important to know what we are dealing with.

ship plan under mag prob sepia diazo 980 2
Left: This sepia diazo plan (c.1962) is printed in reverse and shows the characteristic white back and discoloured front. Right: Under magnification the lines can be seen to be characteristically soft.

“When it comes to preservation of the physical plans we will be housing them in a climate-controlled strongroom: documents survive longer when they’re kept in a stable cool dry and dark environment.”

The support material used for the majority of the Cook Welton & Gemmell ships plans is tracing cloth, a heavily-sized semi-translucent material widely used because it is stronger than paper. Tracing cloth is made from fine woven cotton which is then impregnated with resins, coated with starch, (and frequently other additives such as oil, clay, blue pigments and later on, synthetic plasticisers) and then pressed between plates or rollers to give it a smooth glossy surface. Tracing cloth had been commercially available since the second half of the 19th century and really took off with the invention of the blue-print process in the 1870s.

ship plan under mag prob gel litho 806 (3)
Under magnification the heavy starch coating and woven cotton can be clearly seen on this c.1949 plan, probably gel-litho.

As resilient as tracing cloth is compared to paper, it is susceptible to mould and distortion when exposed to moisture. Many of the plans in the collection have been rolled then squashed flat during storage resulting in creases and a few show signs of minor historical mould damage. When it comes to preservation of the physical plans we will be housing them in a climate-controlled strongroom: documents survive longer when they’re kept in a stable cool dry and dark environment. They will also be stored in archive boxes which provide an extra layer of protection from impacts, dust and environmental fluctuations.

Although they are a case of form following function, these plans do have a certain visual appeal. Check out the image gallery of plans already digitised by our hardworking (and patient!) volunteers.

Kat Saunt:  Conservator

(East Riding Archives)

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