Case of a 150 year old engineering drawing

June 26, 2018   By Manit
When we first saw the drawing on site, it appeared to be in a fairly good condition. Once it arrived in our conservation lab and we started a thorough diagnosis, there were a lot many observations and analytical details that were required to be considered before any treatment methodology could be prescribed or finalized. In this blog post we will share some simpler diagnostic observations. IMG_5064
  1. The drawing is showing full-width horizontal creases at regular intervals suggesting that it must have been kept rolled for a long time before getting framed.3
  2. There are creases and marks created by framing too. 9cats
  3. Apart from the horizontal creases created by rolling, there were many smaller creases in vertical direction (may be because of handling). 10

4. Besides the physical distortions like creases, we also found a couple of biological deteriorating agents, namely, fungus/mold and termite larvae.


possibly, larvae of termite

5. Another interesting feature is  regarding the apparent surface coating provided between the first draft and the final drawing. This is evident from two observations:

a.  We can see a clearer original paper in a portion where a drop of water or some other liquid seems to have fallen. 3

b.  Certain areas have lighter ink as there seems to be a layer of some surface coating and some other lines are drawn on top of the surface coating.  The surface coating also bears tiny brownish fibers that are just on the top, not in the depths of paper.4

                                     Detail showing under-drawing and the top lines


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