This weblog includes several posts (some in draft form) that reflect my notes regarding PEG (polyethylene glycol) treatment for waterlogged wood. The posts, when complete, will include:
1) PEG Summary: Alaska State Museum (this post)
2) PEG Bibliography Annotated (with Dana Senge)
3) PEG Shipwrecks
4) PEG Basketry (with Dana Senge)
5) What Do We Know About PEG?
6) Waterlogged Wood Deterioration
7) PEG Adhesives
8 ) Early PEG Treatments at the Alaska State Museum
All of these will be incomplete, but are the extent of my notes and investigations to get the Alaska State Museum lab up-to-speed for PEG treatment. Since it has taken me WEEKS of reading and pondering over the past two years, it seems that this effort might be useful to others in a public forum like this blog. Conservator Dana Senge (DKS Conservation) is also grappling with these issues and we’ve teamed up to share our observations and investigations. Dana will be treating a wet basket excavated recently on the property of the Baranov Museum in Kodiak, Alaska. I would imagine if she gets up to speed on PEG, she will be an excellent resource for people who have this kind of material that needs to be treated since she is a conservator in private practice. CCI treats some of this kind of material, but only from Canadian sites and only those that they have the resources to commit to.
The Alaska State Museum has several baskets from a Baranof Island site that are in water, dated around 4, 000 years old. Probably spruce root. One basket from this group, as well as the even older Thorne River basket, have already been treated. The protocol, recommended by CCI more than 10 years ago, preserved the baskets but has left them fragile and impossible to handle, exhibit or travel. Perhaps travel will never be possible, but there is a great desire (especially among weavers) to have them travel to communities in Southeast Alaska. To that end, I am looking into variations on the PEG treatment to make the remaining baskets more robust, as well as methods to further consolidate the surfaces of the baskets already treated. I am nearing the end of a test of higher mw PEGS in samples of the yet-untreated archaeological material. I am still rather early in the testing of possible consolidants but am focusing on the use of an asthma nebulizer for application.
There are certain aspects of the PEG literature that I am not looking at too closely. One is freeze-drying, since we don’t have a freeze drier. I am not completely clear what is happening, however, in just using a low temperature tissue freezer (-35C) I am guessing that there is a bit of freeze-drying that happens, since the basketry does lose weight in the freezer, but that perhaps there is also some evaporation of liquid water with the subsequent controlled slow-drying? I am also not particularly concerned with biocides, since we are using small quantities of PEG with these small artifacts and we can jsut make up a fresh batch if we have biological growth. I suppose this might affect biological activity that I can’t see, but I have a gut-level instinct that adding in more chemicals makes the whole PEG-wood-water system even more complicated and unpredictable? Ditto with including anti-oxidants, although I still worry about oxygen accelerating the breakdown of PEG over time. And then there is the issue that these baskets might have iron in them that would eventually produce acids…should I be trying to remove that iron first? The poor baskets have been waiting for treatment for 10 years now. Part of me just wants to get ON WITH IT ALREADY! Don’t be such a chicken! But there are always more articles to read, more people to talk to…how many people in the world really understand PEG treatment after all? Just a handful, I’m sure, can really grapple with all these variables. And those few people can’t treat everything that is out there, although they have been heroic in the publications they have produced.