Paleonet: A sticky situation

Howard Gibbins gibbins at ualberta.ca
Tue Feb 23 03:43:00 GMT 2016


Greetings,

I recently ran across an odd situation, and was wondering if anybody has, and whether they may have a solution?

One of our volunteers recently prepared three Ceratopsian pedal phalanges. They were easily cleaned and had minimal matrix. When they were done the specimens were given a coat of Paraloid and put aside ready for cataloguing and storage. This all happened at the very least 4-5 weeks ago. 

When I went to pick up the three specimens the other day Paraloid had not hardened, and in fact the surfaces of the specimens were extremely sticky. The specimens easily adhered to my fingers, as well as to the wooden tray they were laying on. It felt like they had been dipped in a thin coat of honey.

It was easily removed with acetone, after which I let the specimen air dry and then gave it another coat of 1:10 Paraloid. Within a few hours the surface was once again sticky (although not to the same degree-thankfully). We have good air circulation in the lab, and the temperature is constant at approximately 20 C. We don’t have anything in the lab that the volunteer could have mistakenly put on in place of Paraloid in the first instance, and I know it was Paraloid I put on, as I’d been using it all day and everything else worked properly.

So the question is does anyone know of anything that can prevent Paraloid from drying, and even seemingly thicken it on the surface? I assume it would have to be some chemical / or mineral that had leeched into the bone during the fossilization process, or that the bone was exposed to prior to collection, and was possibly released by interaction with the acetone. Unfortunately I wasn’t the collector, so I don’t know the environmental conditions at the site, but it came from Dinosaur Provincial Park in Alberta.

Thank you in advance,

Howard Gibbins
University of Alberta
Laboratory for Vertebrate Palaeontology
Edmonton, AB., Canada
(780) 492-9366


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