Treating the back of a canvas painting

Reports and write-ups on “Conservation of a canvas paintings” generally skip or very slightly mention the problems (and their treatment) at the back of a canvas painting. We need to understand that back represents the health of the canvas support on which the paint layer is resting. Dust/dirt has a tendency to collect on the back of paintings. It settles between the canvas and stretcher bars, and gets engrained in the exposed canvas.

In this write-up i will discuss  how we might be able to treat some common problems at the back of a painting to avoid accelerated degradation of the painting. Here i would share the experience of treating the back of a painting in our conservation lab these days.

Following pictures would help understand the problems that need treatment to improve and increase the life of a painting:

dirt accumulation, water damage, tide-lines, old repairs, tapes
Dust has been removed with the help of dust attracting sponges in some of the area
water damage causing tide-lines and accumulation/concentration of acidic and other components at the tide-line

From the pictures we can identify some basic problems in this particular canvas painting, for which we can create a methodology and start treating. We might find more problems or new more accumulated deteriorating agents while cleaning the back.

We started treating the back of this canvas painting from simple to more thorough and comprehensive cleaning procedures.

1. Removing the dust with dust attracting sponges, brushes and vacuum

The loose dust and accretions are easily removed with brushes. More deeper dirt is picked-p with dust attracting sponges and mini vacuum.

Dry-cleaning sponges being used for picking up dust that wouldn’t go by simple brush and is stuck up in depths of the canvas texture

 

Right portion of canvas in the picture is cleaned with dry-cleaning sponges

2. Treating the tide-lines with agarose gel

Tide lines are actually concentrated accumulation of various water-soluble components accumulated in the canvas because of spilled over water and its movement through capillary action.

Tide lines are the result of a chemical reaction when contaminated water reacts with soluble degradation products in canvas (or paper, in case of paper paintings) that has the ability to pull liquids either by wicking or capillary action through the material to the point where evaporation takes place leaving behind the contaminates and degradation products producing a line that disfigures the object and weakens it.

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At room temperature, individual agarose pieces are applied to a portion of tideline and allowed to rest on the surface for some time. The agarose pieces imbibe the soluble components in the tide-line during contact with the surface of the canvas, by diffusion and capillary action. Slow acting agarose pieces not only pick up the acidic and damaging water soluble components of the tide-line but also hold moisture in check .

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Most of the water soluble components of tideline are absorbed by the agarose gel, rest were diffused.

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All the tidelines were carefully removed from the back of the canvas and it looked much better than before. There were still some stains and some diffused components left from the tide-lines.

 

3. Cleaning with pH adjusted water

The back was further cleaned with adjusted water and results were great.

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Whatever processes we were doing at the back, we checked regularly if it is affecting  the front. Some tests were also being conducted at the front in between the three cleaning processes of the back. It was interesting to note that as the back was cleaned, the complete painting (both from front and back) looked healthier and much more treatable.

Author: namitajaspal
Namita Jaspal, with inherited skills of art and aesthetics and passion for science, opted to pursue post- graduation in ‘Conservation of Cultural Property’ after her graduation in Science from Delhi University in 1992. Four year intense training at National Museum Institute provided the right foundation to start a career in Conservation. She is currently practicing conservation consultancy for Heritage property including monuments and collections. She has been doing independent research in conservation techniques and procedures in Indian context. She is currently working on the conservation of wall-paintings of Sri Harmandir Sahib Ji (The Golden temple at Amritsar. The project is nearing completion and getting a lot of appreciation for the organized and ethical treatment it is providing. It is for the first time in the history of Sri Harmandir Sahib Ji (The Golden Temple) that wall painting conservation and preservation is being done in a scientific manner, keeping the codes of Ethics into consideration while decision making. Another project just completed is of the Conservation of Krishna Temple at Kishankot, Gurdaspur, Punjab. In her private Conservation Laboratory, she is not only providing onservation services, but also mentoring young aspiring conservators and archaeologists by the way of training and paid internships. She has been a guest lecturer at DIHRM (Delhi Institute of Heritage Research and Management). With all the updated knowledge database and innovative practical approaches relevant to the Indian conditions, she could successfully do curative and preservative treatment of very old textiles like a nine feet long flag from nineteenth century that is regarded as priceless memorabilia of second Dogra regiment at Chandi Mandir, and four hundred years old (seventeenth century) Chola Sahib Ji of Sixth Guru of Sikhs, Sri Hargobind Sahib Ji. Apart from this she has done conservation of Photograph collections, archival records, numerous paintings, manuscripts and other cultural objects. She is also involved in preparation of up-gradation proposals for museums and such organizations. Her expertise includes Conservation and preservation technologies and procedures for conservation of varied material like wall paintings, paper, photographs, textile, ceramics, stone, metal and archaeological objects.

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