Saturday, November 21, 2009

Rehydroxylation Dating-- 10-21-09 update

Our collaborating student researchers are making steady progress in their efforts to replicate the ceramic rehydroxylation dating technique published by Moira Wilson and her colleagues over the summer. If you wish to read all my posts about rehydroxylation, click here.

Helen Ranck, Patrick Bowen, and Jessica Beck have been working on different parts of the problem and they've learned a great deal so far.

Here is one of Helen's graphs that describes the mass gain of one of her test samples:
She and Patrick have been trying to find out the best way to keep the sherds at a constant temperature and atmosphere while the fragment absorbs water. Patrick has discovered some key changes in practice that have really helped reduce the variation in calculated dates, bringing the projections closer to our expectations. Jarek Drelich, associate professor in Michigan Tech's Materials Science and Engineering department, has been very helpful working with them both.

Jessica Beck has finished some of her testing. She calculated the porosity of a group of the sherds using a methodology outlined by the National Institute of Standards and Technology (NIST). Jessica discovered that the Davenports' earthenware ranges from 10%-15% porous, and that both the median and the mode will be around 13% or 14%. I'm looking forward to her final conclusions and her estimates on firing temperature as revealed through her other testing!

Friday, November 13, 2009

Lab photo update

The students are working on their projects and Jessica is making progress on cataloging the collection from the Davenport Pottery site dig.

Max and Allison are cataloging their pottery frags and getting ready to start their cross-mending study.

Frank is studying the charcoal we recovered from our flotation of sediment samples. He hopes to describe the Davenport family's choices for fuel use when firing their kiln. He's examining little chunks of charcoal with an optical microscope.

This week I also taught the students the basics of archaeological drawing, drafting, and illustration. We learned by drawing two random objects from the stuff that I keep around the lab for activities just like this. This year we drew a mini-terra cotta warrior, lent to us by Pat Martin, and a model of someone's thumb.

Jeremy was doing a measured drawing using drafting tools.

After working with measured drawings, we also used digital photographs as tools to produce our drawings, but still working free-hand. I taught them stippling, a standard technique for technical illustration. Alison is drawing the thumb in these photos.

This photo and drawing are of the same thumb, but don't show the same view. You'll notice that the light falls from the left in the photo and the right in the drawing. This drawing was by Jessica Beck and was her first attempt to anything like this!

The students didn't finish any drawings, since these objects were just for exercises. If anyone ends up drawing objects in their project, we'll post the final drawings here. Over the summer, we also did technical drawings of the pottery in the Utah State Parks collection. Perhaps we will post some of those drawings as well.