Art Conservation Project: Watercolours of an Early Ontario Naturalist

July 27, 2020 | Wendy M

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Drawing of birds in lab with weight placed on it and brushes and tools nearby
Treatment of Magnolia Warblers drawing by William Pope.

In 1917, Toronto Public Library acquired 226 drawings of birds and mammals by William Pope (1811–1902). Pope lived much of his life in what is now Ontario. He was Canada’s first artist-naturalist of European background. Learn more in our post about Pope.

These beautiful watercolour and ink drawings date from the 1830s to 1860s.

They are held in the Baldwin Collection of Canadiana on the 5th floor of Toronto Reference Library. Some of the drawings are digitized

Back in 2009, our conservators created a long-term preservation plan to treat and properly store these pieces of history. While our conservation lab was temporarily closed due to the COVID-19 pandemic, we put together this summary of the process.


Condition of the works

A survey of previous ad hoc treatments was completed, noting how many of the watercolours were still matted and framed, and how many had been unmatted for exhibitions in the TD Gallery at Toronto Reference Library.

The watercolours were matted and framed with acidic materials. Acidic mats and backing boards stain and weaken the watercolours.

Of the 226 drawings, 144 had never been treated.

Illustration of black bird on old paper in frame withe surroundings of measurement tools
Framed Pope watercolour of Magpie showing its greyish window mat. Note the brownish edges of the mat window and the caption below, clear signs of acidity.


A multi-staged treatment plan spanning many years was made. It allowed our conservators to gradually work their way through the treatments in between their other work.

The individual watercolours were painted on heavy-weight, high-quality wove paper. Unfortunately, they had been mounted to an acidic backing board with an acidic window mat glued to the front of the watercolour with animal glue. Treatment included removing the matted watercolours from their frames, followed by mechanical removal of the window mat and caption.

Once the window mats were removed, the water soluble animal glue could be removed. This first stage took about two and half hours per drawing.

Side by side images of old paper drawings with the left one showing debris along border and the right image showing no debris along same border
Left: details of acidic mat board remnants glued to the Warblers’ watercolour. Right: A clean border after glue removal.

A common condition issue is mat burn, a reddish-brown linear stain formed where the mat window opening contacts the watercolour paper. Acidity stains such as mat burn are not easily reduced. That's why good quality mat board is always recommended for valuable works. No attempts were made to reduce the mat burn stain.

The next stage is the most tedious: completing a backing removal of the acidic mounting board. This is a very slow, precise process, carefully thinning the layers of the backing board mechanically. Estimated time for completing this stage was four hours per watercolour drawing.

Old paper drawing of bird with paper curled
This ink drawing of a Red Headed Woodpecker has had both the remaining window mat board and its glue and backing removed. You'll notice that the process has left it a little curled.

Next step: humidification and flattening. The watercolours are placed in a shallow tray atop a water vapour source and allowed to take on moisture for a limited period of time. Once the watercolour is limp and relaxed, it is carefully transferred to a cotton blotter stack to dry under weight for a number of days.

And then the treatment is complete!

Flat paper drawing of bird with long beak
The woodcock after humidification and flattening. An example of piece after treatment.

A revitalization of the project in 2016 focused on unframing and removing the window mats on all the remaining watercolours. These two procedures are relatively quick, and were completed in a number of weeks. Since adhesive reduction and backing removal are relatively lengthy processes, they will be performed at a later time.

Now all of the watercolours have reduced contact with acidic materials, which is key to preserving them for current and future research.


Storage and access

Prior to the completion of unframing, the collection was spread across different locations. Now the collection is together again.

All of the Pope artworks have been placed in individual folders and temporarily housed in archival boxes. This has a double benefit: the watercolours are more accessible than when they were framed, and the dark storage helps keep their colours vibrant.

We also digitized several of the works for better access: check out high resolution versions on our Digital Archive!