Printing on Plastron Pieces

The best plastron print obtained so far

I've been getting better results from my latest experiments with printing on turtle shell fragments. I'm calling them my "Plastron Prints" even though not all the bits of shell are actually from the plastron. I just happen to like alliterative appellations.

There have been three new prints on larger pieces of shell, all fairly successful. In each case, the chemistry displayed the same odd behavior that I was puzzling over in the last entry. By the time each one was dry, it had turned extremely dark and a blueish-green-yellow far from the ordinary color expected of unexposed chemistry. I went ahead with the printing, despite the discoloration.

The bones don't look like they're exposing properly, but they do come out pretty much spot-on. Directly after the exposure it isn't easy to be sure what the final result will actually be. It takes a peroxide bath and a complete drying cycle before the image is plainly visible, but eventually they look like the one displayed here.

Dandelion plastron print

As a side note, I've found a way to accelerate drying of these bone prints: a toaster oven. I dry my bone prints on a sheet of parchment paper in the toaster oven. I run them at 180° F, in 15 minute cycles. Generally a single cycle is enough to dry the bones, but sometimes I run a second cycle just to be extra sure. There has been a slight issue with the high temperature melting any residue scale left on the bone, but this is actually a bonus for me. I want that stuff gone anyway, and if it melts off, that's fine. It turns into brown goo that I can scrub away with a bit of effort, instead of having to sand it off with a lot of effort.

My last experiment was trying to reclaim some of the earlier pieces that I discarded as ruined by the chemical exposure. Now, having learned what I have from these last three pieces, I actually feel certain I could have exposed those earlier pieces and gotten results. I was just too put off by their odd initial appearance to try. So far, I only have one result from this new experiment, and it isn't quite what I wanted, but it is encouraging. I soaked the discarded fragments from the first run of coating in a strong soda ash solution to bleach away the blue. Once they were completely bleached, I washed them twice and allowed them to soak overnight in clean water to remove any trace of the chemistry. Then, after two drying cycles in the toaster oven, I re-coated the shell fragments in new chemistry.

First re-coated plastron print

The first result is, as I noted, encouraging. It has a distinct image visible, even if the coating of blue is a bit patchy. I'll be doing more of these to see what I can get with better, more even coating.

As always, the entire series of experiments can be viewed on Flickr or Instagram.