XRF: Why Should We Get One?

Scott Carrlee and Ellen Carrlee test an arctic tern specimen for arsenic at the Alaska State Museum

The Alaska State Museum has decided to pursue funding to purchase a portable XRF machine.  I’m typically skeptical of technology and reluctant to commit to learning elaborate and expensive techniques I would rarely use.   But in this case, I think YES we should get one.  Here’s a timeline of the decision-making process and what’s made me come around. 

Bruker handheld XRF analyzer

June 24, 2011  Handheld XRF Workshop at the Pratt Museum in Homer.  Dr. Holly Cusack-McVeigh (curator) had been talking with paper conservator Seth Irwin about her concerns loaning out potentially pesticide-contaminated natural history specimens.  Seth knew that some archaeologists in Fairbanks (Jeff Rasic and Josh Reuther) had been using a Bruker XRF for obsidian studies and geological questions. They helped Holly connect with the Bruker scientific rep, Bruce Kaiser.  Bruce was already coming to Alaska to do a training for the Fairbanks archaeologists, and Holly sweet-talked Bruce into an extra training in Homer, with promises of scenic beauty and fish dinner.  The Fairbanks archaeologists attended the Homer training too, and so did Scott Carrlee (Alaska State Museum outreach curator, trained as a conservator) who happened to be doing a survey in Seldovia at that time.  After the training, Bruce Kaiser offered to send the XRF to Alaska on loan.  Smart move, Dr. Kaiser.

July 29, 2011 The XRF arrived at the ASM on loan, where Crista Pack was still doing her summer internship.  As a conservation grad student from the U Delaware/ Winterthur program, Crista had already had some XRF training with Bruce Kaiser.  She was doing a project for the ASM, “What’s That White Stuff?” and helped us kick the tires and take it for a test drive.

Alaska State Museum collection II-A-77 Siberian Yupik pipe from St. Lawrence Island

August 9, 2011  One artifact in particular, a leather tobacco pouch attached to a pipe, brought home to me the utility of the XRF.  I wanted to know if the white crytals on the leather were from lead corrosion that was prevalent on  many of the pipe bowls in the drawer, or perhaps a fatty bloom from a long-ago leather dressing, or maybe arsenic to prevent insect infestation.  What would the XRF say?  It told us we did not have arsenic or lead, but we did have a significant amount of potassium, which made me think about potash in the tobacco mixture the bag would have carried.   This kind of info is really helpful for treatment decisions and handling protocols as well as artifact interpretation, and the XRF was so much faster than the other techniques I know of…without sampling!  I could test for lead with plumtesmo papers, and test for arsenic using potassium hydroxide/ hydrochloric acid/ zinc with mercury bromide test papers…but just those two tests would have taken me more than an hour, and I still would not have known about the potassium.  And really, I probably would not have occasion to spend so much time determining “what’s that white stuff” for this artifact.  But if it is quick like this, there are so many more questions I am able to pursue.

September 2-3, 2011  In addition to analysis like pesticide testing (the arctic tern had arsenic), pigment examination (a mysterious atl atl had mercury in the red pigment, suggesting cinnabar which would be appropriate for an authentic old throwing board), material identification (a woody-looking fiber contained sulfur, suggesting baleen instead of a plant), looking at potential exhibit and storage materials (vulcanized rubber gaskets), and “what’s that white stuff”, we managed to pull off some educational programming. We went on the radio and in the newspaper to promote a “science gun” public program, inviting the public to bring a small metal artifact to the museum for testing.  I cobbled together a cheat sheet of various metal alloys and the mineral content of certain gemstones, and we looked at over 100 artifacts from people in the community, right there in our exhibition gallery.  The conversations were really dynamic and engaging, and we were using the XRF in conjunction with a couple of other techniques, like UV light to see fluorescence of certain gemstones.

Scott describing a silver alloy during the public program.

September 6, 2011 Just before we packed the machine up to send to Monica Shah at the Anchorage Museum, a group of high school students came to the conservation lab for some science-meets-art demos.  We chatted about the periodic table, elements, valence electrons, and the like…then used the XRF on various student bling and discussed the results. 

No, we didn't actually use this event notice. It was a joke from Paul and Jackie in our exhibits department...

September 26, 2011 Several of us attended another training on the way home from the Museums Alaska conference. For Monica Shah (head of collections and conservation at the Anchorage Museum), Scott Carrlee, and Holly Cusack-McVeigh, it was their second training. It was my first, and I was thrilled to get some of my questions answered after taking the XRF for a spin back in Juneau with Scott and Crista.  Monica had the loaner XRF at this time, and it was heading to Holly next.  We encouraged Holly to try the public program angle we had done in Juneau, and gave her my “cheat sheets”.  Upon my return from the training, I wrote the following for the Alaska State Museum Bulletin:

“Ellen Carrlee and Scott Carrlee attended a day of XRF training September 26, 2011 at the Anchorage Museum at the invitation of Head of Collections/ Conservator Monica Shah.  They were joined Holly Cusack-McVeigh and Bill Walker from the Pratt Museum in Homer.  The training was led by Dr. Bruce Kaiser, a name well-known in museums and universities for connecting institutions with handheld X-ray fluorescence  technology provided by the company Bruker AXS.  One of these “science guns” has been traveling between the Alaska State Museum, the Anchorage Museum and the Pratt Museum, on loan from Bruker.  The device shoots photons (or low-energy X-rays) at a sample, analyzing them non-destructively by measuring the movement of electrons.  After a few seconds, a graph of peaks appears on the computer screen and the software helps identify which elements are present in the sample.  Knowledge of physics and an understanding of how the machine works greatly enhance the interpretation of the data.   Museums worldwide have been using XRF extensively in recent years to explore questions of alloy compositions of metal artifacts , pesticide contamination on ethnographic and natural history collections, pigment identification , and other questions that can investigated with elemental analysis. We’ll keep you posted as we discover the potential benefits offered for Alaskan collections.”

Some of the white powder that was making Holly nervous

October 21, 2011  The Pratt Museum in Homer hosted a free evening public program called “Trinkets or Treasures?”  Holly says it was huge success and great fun for staff and visitors alike.  During the time she had the machine, Holly focused on arsenic testing of taxidermy.  Now she is turning her attention toward possible organic pesticides, but the pile of work has been narrowed down from the first round of XRF testing.  She no longer feels bad about turning a school down for a loan of puffins now that she knows for certain they have arsenic on them.  She tells me that as user-friendly as the instrument is, she knows there is even more information to be pulled from the data that she isn’t trained enough to extract yet.  I have that same feeling…we are getting amazing info, but it is the tip of the iceberg.  I also agree with Holly in her observation that the XRF is so helpful for collections research not just in answering questions we already have (Is this really silver? Is there arsenic here?) but also in sparking new questions we never would have thought of before. Holly sent the loaner XRF over to State Archaeologist Dave McMahan.  He and Dr. Charles Holmes have been using it to examine glass trade beads and glazes on ceramics.  I believe the touring XRF is now back with Bruker.

November 18, 2011  Scott and I are working on a grant proposal to buy the XRF.  Not only could we use it for public outreach and researching our own collection, but Scott could take it out on site visits to museums and cultural centers statewide and loan it out to institutions with staff who have had XRF training.  Holly suggests we might be able to have an XRF training workshop at the next Museums Alaska conference to increase the number of museums in Alaska who could get the XRF on loan from the Alaska State Museum.  As I write this, Scott Carrlee is soliciting letters of support for the grant.  I’ll keep you posted if we get it!


3 Responses to XRF: Why Should We Get One?

  1. Wlodek Witek says:

    Good article, thanks. We are also thinking of the XRF and need background info.

  2. […] As many of you may have heard, the Alaska State Museum was able to purchase a Bruker Portable X-Ray Fluorescent Analyzer through a generous grant from the Rasmuson Foundation.  For some background leading up to the purchase you may want to read Ellen Carrlee’s blog posting on the subject.   https://ellencarrlee.wordpress.com/2011/11/18/xrf-why-should-we-get-one/. […]

  3. Kate says:

    Ellen, for marking on the back of resin-coated photos, Cretacolor solid graphic artist pencils work better than the blue ones. The softer the easier to write. Recommended by a conservator at CCAHA in Philadelphia.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: