Conservation internship (2022) at HPA

INTERNSHIP EXPERIENCE- OIL ON CANVAS PAINTING

– Priya Agarwal

Each painting has its own character, its own challenges and therefore requires an individual treatment. During my internship at Heritage Preservation Atelier, I had the chance to observe these variations firsthand. Being a part of HPA’s interdisciplinary environment and learning more about how science and art can coexist were two of my main reasons why I wanted to intern here. I arrived in the lab at a busy period, when more than five paintings were being worked on.

I spent my time learning various documentation techniques, cleaning methods, mending and framing of an oil on canvas painting. Documentation is an ongoing process at every new stage of the conservation treatment, and it involves photography and making condition assessment reports. A painting is said to be well documented if every step is photographed properly and a before and after treatment picture is taken. A detailed condition report includes pictures showing the damages, a written summary of deterioration and its probable causes and the proposed treatment plan. Before starting the cleaning process, it is of utmost importance to acquire a thorough knowledge of its material composition. The structure of an oil on canvas consists of many layers: auxiliary support, canvas, size, ground, paint layer and surface coating (or varnish).

The back of an oil painting is often the most overlooked aspect of the artwork. Although this area is often ignored, it is by no means less important. The accumulation of dirt, dust and grime, while a painting has been hanging can be substantial. The painting is first removed from its stretcher bars in order to thoroughly clean the back. Some of the dry cleaning methods that I learnt during the process were using brushes to remove the loose dust, sponges, kneaded rubber/archival eraser, and vacuum used to remove the engrained dust in the canvas. One of the most exciting things was getting to know about treating the tide-lines with agarose gel. An area of tideline is covered with agarose pieces which are left to rest there for a while. In contact with the canvas, the agarose pieces absorb the soluble components by diffusion and turn yellow.

Mechanical wear and tear of the canvas by repeated stretching, abrasion with stretcher bars and the holes caused by the use of nails weaken the canvas support near the folded edges on the stretcher. Tears or holes in canvas paintings can be repaired using a number of different techniques and materials. One of the methods I learnt here is thread-to-thread mending of the torn area. An adhesive is applied with a hot needle to attach the loose threads to the torn thread ends around the large holes or tears. Another method which I used to mend the small holes is called the patching method:

  • Firstly, I chose the canvas that closely matched the original one and aligned it with the weave of the painting.
  • A patch of canvas was traced and cut to the exact size of the hole.
Tracing the lost area
  • The edges of the patch were then chamfered and pasted to the back of the canvas using a heat activated adhesive (BEVA film) with the help of a tacking iron or a heated spatula.

After all the tears are mended, the front of the painting is cleaned thoroughly using solvents and gels. Sometimes the painting gets darkened or turns yellow due to ageing and darkened varnish which covers the finer details of the painting and hides the original paint. Before starting actual cleaning, patch tests are often conducted on small unimportant areas of the painting to choose a proper solvent and method of application. This process helped me gain comprehensive insight into various chemicals and solvents being used in cleaning.

Comparative study of cleansing systems

I also assisted with the process of framing paintings. It is significant both aesthetically and as a preventive conservation measure. A frame protects an artwork during handling, storage and display. Therefore, to ensure the safety of a painting and prevent damage, it is crucial to use correct framing techniques. All paintings should have protective backing boards. Foam core board is a lightweight acid-free board consisting of micro-chamber technology. It is a safer backing than regular plyboard and is ideal for the mounting and backing as it prevents the artwork from harmful gases. In one of the paintings, the client wanted to get the frame repainted. Here I got the opportunity to make a comparative analysis of the effect of toluene, xylene, acetone, xylene-carbopol gel and acetone-based gel in the removal of thick paint layers. Later, a paint removing gel was used to remove the remaining paint. A micro-emulsion was prepared in the lab for cleaning thoroughly the underlying surface.

Removing paint layers from the frame with the help of different gel preparations

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