Consolidating film fossils

[connorp]

I recently acquired this nice algae specimen from one of the many Chinese Cambrian lagerstatten (Hongjingshao fm). The algae is preserved as a film on the shale, and unfortunately the shale is quite flaky.

Several pieces of the lighter gray matrix have flaked off already, and there are quite a few other areas that look like they could fall off with the slightest bump. I can go ahead and glue the pieces that have fallen off back on, but I'd like to prevent the rest from coming off.

 

However, I'm worried that the algae would quickly wash away if liquid touched it, especially something as harsh as acetone (if consolidated using standard methods). This is certainly the case with many fossils from similar formations. Do I have any options here?

[Wrangellian]

Interesting piece... Where can I get my own specimen? 

I would try my best to avoid coating the surface with anything, otherwise you might lose something in the process - either the contrast of the fossil against the matrix, or a shininess which would hinder photogenicity [there's a word I've never used before but I'm pretty sure it's a word].... but I might try applying some thin Paraloid/Acryloid solution or maybe superglue into the sides (edges) where it can wick into the cracks, hopefully without it flowing out onto the fossil surface. Let us know how you make out.

[Ptychodus04]

@connorp, I would heavily consolidate the back of the slab with Paraloid/Butvar/Vinac. Then, drip/brush the same onto the edges, allowing it to seep into any cracks. For the front, you have to be very careful. I have consolidated leaves preserved as thin carbon films in the past using a very thin solution of Vinac in acetone. The trick is to apply it in the most gentle way. 

 

It will take forever, but you can dip a VERY small artist’s brush in the solution and lightly touch the specimen with the dampened tip. The fossil will pull the solution off the brush. I use a brush that is so small that it won’t even hold enough solution to form a drop to do this. In this way, you are not moving the brush across the film nor are you hitting it with the force of a falling drop.

[Wrangellian]

Somehow the material doesn't look all that soft or fragile to me and I would be you can get away without putting anything on the fossil surface itself.

If there are pieces coming off anywhere, it shouldn't be too hard to glue them back on, and wick the thin Paraloid solution into the cracks and edges as described. I find it works better to get the broken piece back in place nice and snug and then wick the Paraloid in, rather than putting a drop of glue down and then resetting the broken piece - the glue could already be dried or partly dried by the time you get the broken piece in place!