Plant Fossils In Shale, Preserving?

[zuke]

Thanks everyone for the good stuff you have on this site. Have been looking around this site for making shale more solid. Thanks for any help with this.

Last month I found a lot of plant fossils in the shale layer from a strip mine cut. A lot of the shale is very brittle. Is there something that can be applied to the shale to keep it from flaking so easily?

I left some large layers outside for my niece to examine and break apart and a rain really took its toll on the surface. I have since covered these.

Another site said to to use PVA glue diluted with water and brush this over your specimens. Another person uses simple lacer or clear varnish.

Right now I have them stored in shallow boxes. My wife wants to place some of the neat ferns and grasses in a shadow box for display. So do I leave them as is and be really careful or do I apply something to them to make them more solid? Thanks again for any suggestions.

[Wrangellian]

I'd like to see pics of the stuff, it depends a lot on the nature of the fossil/rock what treatment you apply, if any, and it's hard to get a feel for that from just a description.

[dshamilla]

zuke,

In some instances, it may be best to leave your specimens as is. That’s up to you. The following are some suggestions you might try for holding friable fossil plant specimens together. Various shale types (colors and compositions) will bring varying results. So, its best to test the material, if possible, for the end results. Also, it depends on whether you want to surface coat or saturate your specimens. Most spray or painted applications provide too shiny or too thick a surface covering on specimens. This can detract greatly from the natural look of the specimens. Too many times I have seen lacquer painted or sprayed specimens that look very artificial when finished. Another thing to consider is that many applications (some lacquers and epoxies especially) yellow or change color with age. Also, many applications will darken the specimens and matrices so much as to become “un-displayable”. Water-soluble, glues and sprays etc. are susceptible to humidity, so I would not recommend them. I would say never use varnish on plant specimens, too thick and unnatural in appearance. (No matter what you apply always make sure the specimens are thoroughly dry before any application). Remember, when using any glues, sprays or paints, always provide proper ventilation. When using acetone, be aware the dangers of the vapors and that it can be absorbed directly into your skin.

Some applications I have used with good success on plant fossil specimens (again, dependent on matrix) are as follows:

For surface coatings of specimens: I’ve found spraying with Testors “All Purpose” DullCoat Flat Clear Lacquer Spray Paint or Krylon Low Order Clear Matte Spray Paint works well. The Testors has worked best for me, though it can sometimes be hard to find. For fine work or delicate specimens, I dilute the spray paint (sprayed in the spray can lid) with acetone and then apply with a brush.

For saturation of matrix (i.e., matrix gluing): I’ve used Duco Cement diluted with acetone on smaller specimens. At one time, I had a 5-gallon container filled with toluene into which used Styrofoam coffee cups were thrown and then dissolved (any particles or other liquids would separate out at the base of the container). The upper clear portion would provide a gluing medium for submersing larger specimens in.

Many times following use of the above methods leads to surface buildup of the gluing medium or a shiny surface finish. Washing the surface with acetone, which dissolves and re-absorbs the gluing medium into the matrix and dulls the surface finish, will help to alleviate these problems.

I know there are many other methods that are out there; these are just the ones I’ve used in the past.

[zuke]

Thank you for the suggestions. I really would like to keep them natural. Gave a layer to the children of a friend and just from passing around had some pieces flaking off. I will try some of the methods on some to see what they look like when finished.

I would like to include photos but will have to wait for my son to help me post them. I am not very computer literate. All the fossils are fresh water plant material. They were in a grey shale layer that was above a coal layer. The fossils appear black. We were lucky on some to fracture the shale layer at the right place to get the plant on 1 layer and the imprint on the other. Another amazing thing is that on some layers there is still actual plant material.