The power of drawing

I bought a painting from an exhibition of local artists. It is a mundane sounding subject: Landscape of the Manchester Ship Canal looking towards the Barton High Level Bridge. If you have visited the Trafford Centre, you have probably been there. The canal and the bridge have been a constant feature in my life, but that was not the main reason for buying the painting. They fill only a third of the canvas and the remainder is the sky, where the sun is struggling to break through some dark threatening rain clouds while illuminating the land below. It evokes the sentiments of home with ever-present rain clouds and always the possibility that they will soon clear away.

I have long been in awe of people who are able to paint or draw and capture both the likeness and the essence of a person, animal, place or object. I did not do art at school and the nearest I came to drawing was making diagrams of experimental equipment in science. So, not too long ago, I decided I would try to develop my drawing ability. This was not as big a challenge as you may think; I was starting from such a low base that anything would have been an improvement. I still do not practise as much as I should, usually only on holiday, but at least now my sketches of birds no longer look like two ping-pong balls stuck together, with a beak on one and legs and tail on the other.

It is 25 years since the founding of the Royal Drawing School and The Times marked the occasion by interviewing various artists about why drawing is important to them. Two particular quotations resonated with me. David Hockney said: “Drawing allows you to see the world more clearly. It is not just about recording reality, but about understanding it in a deeper, more intimate way. I do think that drawing is really about noticing.” Antony Gormley described drawing as “the freedom to dream as well as the diagnostic ability to work out relations between parts and wholes”. Even as a novice I can see the truth in these statements. I can also see their application to non-destructive testing (NDT).

The output of NDT, irrespective of the technique used, is a report of indications observed and in many cases the NDT report once contained a space for a sketch of the indication relative to the component. In the process of drawing this sketch, the operator acquired an understanding of the origin of the indication: where it is relative to the weld, whether it is geometric and whether it is unexpected and likely to be a flaw. It made you see the indication more clearly and enabled you to diagnose its relation to the component.

The Times noted that technology has displaced drawing, but some technology can actually help with the drawing process. Take the plotting of ultrasonic indications. To do this accurately, it is necessary to plot out lines of the precise length at accurate angles to the surface normal. Initially, this was performed with a ruler and protractor, progressing through the use of plotting boards, simple drawing software and computer-aided design (CAD) to the flaw detector providing the necessary stand-off and depth information. In all these instances, despite the technology, it is still necessary to go through the thought process of constructing where and how the indication originates within the component, which is key information for understanding and subsequent interpretation.

However, with more recent technology we have lost this embedding of the process. For visual and surface techniques it is possible to just snap a photograph and put it in a report without any further consideration. With advanced imaging techniques, how a particular image is generated is no longer a concern. The question is whether there is an indication of a certain amplitude and, if so, to measure it to two decimal places using the digital cursor. The images are not even displayed on a one-to-one scale to give a true picture of the indication positions.

I understand that when conducting an inspection, image recognition is an efficient method of analysis when a lot of data is generated. I even used it myself in black and white days. But when it becomes the norm, there is a likelihood that the ability to deconstruct the image and get a better understanding of an unexpected or unusual defect will be lost. With the increasing use of machine learning it will soon become a relic of past operators.

Even if I have not convinced you to better understand the defects you detect and report, I hope I have inspired some of you to pick up a pencil, a chalk or a pen and have a go at drawing. If I can do it, anyone can.

Please note that the views expressed in this column are the author’s own personal ramblings for the purpose of encouraging discussion within NDT News. They do not represent the views of Amentum or BINDT.

Letters can be mailed to The Editor, NDT News, Midsummer House, Riverside Way, Bedford Road, Northampton NN1 5NX, UK. Email: ndtnews@bindt.org or email Bernard McGrath direct at bernard.mcgrath1@global.amentum.com