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Art conservation that does more harm than good

The Night Watch by Rembrandt is one of thousands of paintings to receive the wax-resin treatment. Credit: Wikimedia commons

The Night Watch by Rembrandt is one of thousands of paintings to receive the wax-resin treatment. Credit: Wikimedia commons

Hindsight is 20-20, as they say.

This week Art Daily* reported that a widespread preservation treatment, developed to help canvases survive humid environments, actually makes paintings more vulnerable when humidity levels soar.**

“The wax-resin treatment was enormously popular in Europe and the U.S. during the 1950s and 1960s,” says Cecil Krarup Andersen at the Royal Danish Academy of Fine Arts, who made the discovery. “Many masterpieces, such as Rembrandts and Van Goghs were preventatively treated with wax-resin linings to help protect the artwork from humidity degradation. The treatment does exactly the opposite.”

Anderson has just wrapped up her PhD work on the topic, a research project that began because museum staff at Statens Museum for Kunst were trying to figure out why Danish Golden Age paintings treated with wax-resin were not resisting the insults of time as well as they should.

I needed a little background on wax-resin treatment which Andersen kindly provided: It was popularized in the 1800s by a Dutch restorer named Nicolaas Hopman. One of the first masterpieces to be treated was Rembrandt’s Night Watch in 1851.

The overall motivation was logical: Hopman thought that coating the back of a canvas with beeswax and an extra layer of canvas would act as a protective support for the painting. Later on, he and others began mixing tree resin in with the wax because it added stiffness. Throughout the 20th century, the treatment gained popularity. Until the 1970s.

That’s when conservators started talking about the importance of reversibility, the idea that any conservation treatment on artwork should ideally have an undo button, just in case a treatment turned out to have unforeseen, negative, long-term impacts or in case a better treatment came along sometime in the future. Continue reading →

Wedding Hiatus

Marc Chagall’s Wedding. Credit: Wikimedia commons.

Artful Science is in the middle of a two week hiatus as I prepare madly for my imminent wedding. (Yay!)

In the meantime, it seems somewhat fitting to direct you to a previous post about mysterious green stains on a WW2-era wedding dress.

Also, since my silver wedding dress makes me look pretty much like a space bride (but thankfully *not* this one), I figure a post on spacesuit conservation is also a propos.

Artful Science will be back to regularly scheduled programming in early August…

Sweat-Stained Artifacts

These green sweat stains on a WW2 wedding dress appeared after sweat corroded the copper threads in the fabric. Credit: Australian War Museum

We all sweat.

Some of us do it rather profusely, particularly when life suddenly gets a tad more exciting or stressful than usual. Such as on your wedding day. Or during military combat. Or on your coronation day—if you happen to be royalty.

Clothing worn during historically important events often finds its way to museums, and that’s when a textile conservator will take a good look—and possibly a deep sniff—in an outfit’s armpit region.

According to four textile conservators who humored my—as it turns out—not so absurd sweat stain inquiry, armpit areas can be colored yellow (no surprise there), but also green, orange, brown and red. The quirkiest sweat stain reported was “a grey-green tide-line stain… with a pinkish interior.”

Staining can depend on a myriad of factors, such as the individual wearer’s sweat chemistry, the fabric, the dye, and whether the person was wearing deodorant or antiperspirant.

Consider the case of a World War II wedding dress that crossed Jessie Firth’s conservation table at the Australian War Memorial. Worn by five different women in the 1940s, the pretty beige dress had green armpits. Continue reading →

Arsenic Contamination Of Artifacts

This armadillo's hairy underbelly is not contaminated with arsenic. Credit: Sarah Everts

A few weeks ago I got to touch the hairy underbelly of an armadillo.

Even though it hadn’t been alive for some time, I was still pretty chuffed about the whole experience—I mean, it’s unlikely I’ll ever have such an intimate moment with an armadillo again.

The beast in question had been briefly removed from its basement cupboard home at the North Carolina Museum of Natural Sciences as part of a behind-the-scenes tour during the recent Science Online conference.

The experience of handling a stuffed armadillo was not just exceptional because it’s a stuffed armadillo. The experience was exceptional because it’s rather unwise to spontaneously handle animal or plant-based artifacts found in museum storage rooms.

Until the 1970s, many biologically-based artifacts were doused with arsenic (as well as lead, mercury and some organic pesticides such as DDT) to keep insect and microbial invaders at bay, explained Lisa Gatens, the NCMNS curator of mammals who let me and others on the tour touch the animal. (For the record, the armadillo was safe.)

Since the practice of adding pesticides to biologically-based artifacts began in the 1800s, there are an awful lot of contaminated museum artifacts out there. And many have levels of arsenic that could pose a problem to human health if handled without protection. Continue reading →

Greening Up Conservation Science

My pedestrian Photoshop attempt to give an Egyptian sculpture a greener feel. With apologies to Amenhotep III and thanks to Wikimedia Commons.

Cultural heritage is important so valuable art and artifacts should be protected at any cost, right?

Not so, says May Cassar, the director of the Center for Sustainable Heritage at University College London.

Most museum, galleries and archives take it as a given that air conditioning and pollution filtration are a must for keeping valuable collections in comfortable living conditions, she says.

“But air conditioning and particularly pollution filtration come at a very high cost–not only to institutional budgets but also from an environmental point of view” because fossil fuels are consumed to drive these systems, Cassar explains. “To me it is a double standard to damage the environment outside but protect the environment inside for collections.”

She’s trying to encourage people in cultural conservation careers to consider the environment outside–and not just around valuable collections.

So for example, Cassar advocates that museums in temperate climates–such as the UK–accept some minor risks to collections if there is a possible gain for the environment. For example, a museum might normally use air conditioning to keep humidity in between 50-60%. If the building’s internal humidity would normally only ever range from 40-65%, reaching the outer extremes only rarely, it could be fine for the museum to eschew humidity control without substantially increasing risk to the collection, she says.

Of course, it’s true that some museums don’t have the luxury of a temperate climate… Consider the soul-destroying humidity of Washington DC’s summer months (I barely survived two of them), or the corrosion potential from the high salt concentrations found in the air around ocean-side museums, or the problem New York City’s sooty air pollution raises for valuable collections.

But there may be other ways for museum, archive and gallery staff to go green.
Continue reading →

Dating Silk With Some Fluffy (But Good) Science

Just a little fluff can reveal the age of silk artifacts, such as the age of this Egyptian textile from 900 A.D. Courtesy: The Textile Museum

Scientists at the Smithsonian have come up with a new way to figure out the age of ancient silk artifacts, such as flags, clothing and tapestries, using just a bit of fluff that’s fallen off the valuable textiles.

The only other scientific way to date silk is by carbon-14 dating, which requires about 100 times more sample than the new technique. (There’s another out-dated “stress-strain measurement” test, which as the name suggests, can put precious silk artifacts through some major mechanical procedures to do the dating. Sounds like just the perfect technique for getting on a textile curator’s black list.)

Anyway, the new technique monitors a component of silk called aspartic acid. Silk is essentially a bunch of intertwined proteins extruded from a silk worm, and aspartic acid is found within these proteins.

Aspartic acid can exist in two forms, the L- and D- forms, which have the same chemical formula but are mirror images of each other. When a silk worm extrudes the silk protein, the aspartic acid is only in the L-form, but over time it transforms into the D-form.
Continue reading →