I managed to spend some time this week preparing a few of the finds from Penn Dixie. It looks like I had a few more full trilobites than I had thought, so there was a good deal of material to practice on.
Preparing these Eldredgeops rana is a fairly straightforward job. The shell is thick and forgiving, and there are no big spines, flaky lappets, complicated horns, and the like to present much difficulty. I managed to prepare three, which I'll show in ascending order by size.
Bug #1 - 1.7 cm
This one was fairly small, but I had recognized it as being complete in the field, and my friend Malcolm was able to chop it out of the block with his saw. There are areas on this where I could have bit in a bit deeper around the sides and the anterior of the glabella, but these smaller ones can be a bit tricky. I may take this one back to the bench for some detail work.
Process: a quick trenching with the ARO clone air scribe, some spot work with the pin vise, and three rounds of blasting at 55 PSI using dolomite and the Paasche AECR. No finishing oil applied.
Time: 25 minutes
Bug #2 - 3.8 cm
This shows a before and after picture (in the field, and after prep). This was one of Deb's finds, so I took care not to screw this one up! There is some slight damage to the left side pleura near the ridge of the cephalon, and some damage to the right side pleura as well, but in all not a bad prep.
Process: Alternating between ARO clone scribe and Dremel, pin vise work, multiple rounds of dolomite blasting (20-60 PSI) using Paasche AECR. Finishing is just a light oil to bring out the detail, but it fades back to matte.
Time: 90 minutes
Bug #3 - 4.6 cm
Before and after
This big bug had some issues. When I found it in the field, it had been cleaved diagonally, so there is some missing pleurae bits on the upper left and lower right where the rock had split. I wrapped it up in a secure container, and when I got home I used cyanoacrylate to stick the pieces together with some clamps, and suitable time for curing. Despite the ugly fracture mark with some stubborn glue, it looks okay. I may take to trimming the excess matrix on either side to better centre this bug.
Process: The right side had a lot of bulk matrix which took some time to scribe off. I trenched around to reveal the tips of the pleural segments and cephalon features, sculpted the surrounding matrix a bit to even out the jagged parts, sanded off the scribe marks, and blasted it with dolomite (25-55 PSI) with the Paasche AECR.
Time: 75-90 minutes
There are a handful of others that will need prep, including both prones and rollers. With time and practice, I am doing much better in terms of technique - but there is still a lot to learn. Fortunately, I'm in no hurry and will hopefully have decades to fine tune my preparation skills.
Here are the others in the prep queue: four rollers and two prones: