HUMIDITY, IT’S ALL RELATIVE: HUMIDIFICATION TREATMENT OF A BIRCH BARK CANOE MODEL PART 1

CONSERVATION TIPS & TRICKS

BY: NIKITA JOHNSTON

For this post, instead of focusing on general tips and tricks, I thought I would showcase a specific object treatment that I am working on at Grey Roots Museum & Archives. This fall one of the upcoming exhibits will display a variety of folk art created in Grey County or brought to the county by local individuals. Pieces to be exhibited include: carvings, stitched samplers, hooked rugs and tramp art.

In preparation for this exhibit, I have been given the challenge of prepping several pieces of folk art for the exhibit. One of the pieces I will be working on in the coming weeks is a birch bark canoe model.

Johnston 2015

Donated by a prominent family from Owen Sound in the 1970s, this canoe is a great example of Canadian folk art. Models like this were popular as toys and handicrafts traded among Europeans. Models resembled canoes built by indigenous groups and used by explorers and fur traders in the woodland and sub-arctic regions of Canada. This example showcases additional First Nations influence in the beautiful floral quillwork designs across the sides of the canoe.

Johnston 2015

Unfortunately, this beautiful piece requires some extensive work before it can be exhibited. The canoe, which is in three main pieces, was acquired by the museum in its current condition. At some point in the past, two parts of the bottom hull became detached from the main body of the canoe. Little remains of the original thread used to attach these pieces to the body. As they were no longer held under tension the pieces of birch bark proceeded to curl, as they will do, particularly in low Relative Humidity environments such as we try to maintain in collection storage.

Johnston 2015

At this point, it would be impossible re-attach the hull pieces without damaging them, as they are far too rigid to bend back into shape. The solution therefore is to re-introduce moisture in a controlled way, so that these pieces can relax and be reshaped to better fit the canoe body without causing damage. Unfortunately, as is common in many small museums we do not have a commercial humidification chamber on hand, so this treatment requires me to be somewhat creative!

Source

That’s right ladies and gentlemen, I built myself a humidification chamber out of common materials around our lab, including: an archival quality textile storage box, polyethylene sheeting, double sided archival tape, cardboard tubes, polyethylene foam…and every handy man or woman’s favourite …duct tape. Oh, and of course my water source for raising the relative humidity of my humidification chamber, a small commercially available ultrasonic humidifier.

Johnston 2015

Of course, before beginning the humidification of the canoe pieces, which I will chronicle in Part 2, there are several necessary and essential steps in the treatment process.

Step 1: Condition Report

Before commencing any treatment it is important to document the condition of the piece, examining the object to be treated and describing its current condition in detail, including any damage, or evidence of previous treatment and repairs.

Johnston 2015

Step 2: Spot Test

Before placing the canoe into the humidification chamber, or performing any type of wet cleaning, it is important to test the paint used on the quills for colourfastness and solubility in water. This is a simple test involving distilled water and a cotton swab. The slightly dampened swab is gently rubbed on an indiscreet part of the painted quillwork to test for colourfastness.

Johnston 2015

If no paint comes away, we can assume it is safe for the humidification chamber. Each paint colour is tested in this way as some colours and dyes are more likely to degrade, or run than others. These are often referred to as fugitive dyes or colours. Lucky for me none of the paint colours appeared to be soluble in water. Yay!

Step 3: General Clean

Finally, before starting the humidification process, it is essential that a general cleaning of the surface be conducted. This is to ensure that any addition of moisture does not cause the surface dirt to penetrate into the birch bark causing irreversible staining. Cleaning also provides another opportunity to examine the piece in detail and note any areas of potential weakness.

Cleaning is done mechanically using soft brushes, a vacuum and sponges. If necessary, a wet cleaning may be performed using cotton swabs slightly dampened with distilled water. As birch bark is hygroscopic, and has the potential to warp with the addition or removal of moisture, a wet clean must be done carefully so as not to introduce more moisture than is necessary to remove the surface dirt.

Now that my initial steps are taken care of, it is time to begin the humidification treatment. The aim is to raise the general humidity without soaking the birch bark or quills, allowing the bark to relax and be reshaped without causing unnecessary damage. Humidification should never be hurried, nor taken to excess, and care must be taken in terms of monitoring for potential mould growth.

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Research has shown that previous humidification treatments of birch bark objects have taken up to several days, hence the reason for a two-part post.

Wish me luck for Part 2!