Tuesday, June 23, 2009

Acid preparation, Part 2

I'm trying the delayed posting utility, so we'll see how this works when I'm done with my road trip.

Here are some more photos of the acid preparation experiment I tried last month. I shouldn't say 'tried' - because this succeeded beautifully. The jaw took about 8 days of acid bathing to completely remove all of the nodule. It did take about 3 gallons of vinegar (3.2 or 3.5 % Acetic Acid, if I remember correctly), which made for a grand total of $6 - definitely worth it, especially considering that there aren't any tool marks now, and I didn't really have to lift a finger. All this took was checking it daily, and replacing the vinegar after each 'batch' had been used up, so to speak (can you tell I didn't do well in chemistry?).
Photo of the specimen after 140 hours of acid preparation.

In any event, I am extremely happy because many fossils from this locality occur in nodules, and they are all of this same sediment with calcitic cement. I'll be at this locality in three days, so hopefully this time I'll find a skull or something else really neat.

Photo of the finished specimen after 200 hours (8 days) of acid preparation.

1 comment:

Brian Lee Beatty said...

Wow, that really looks great, and for the cost it is certainly worth it. My only concern is for future work on microwear of any specimens containing dentitions. Though gross dental wear is unlikely to be affected, I would be surprised if acid preparation can successfully avoid erosion of enamel that would damage microwear features, at least at the smaller scales.
The FLMNH prep lab always kept records of every preparation job, including methods used. That is not always available from museums, though I hope when acid preparation is done, most people find a way to include that sort of information somewhere with the specimen record. I wonder, how many museums keep preparation records with their specimens?