How To Keep Fragile Shale Fossils From Breaking

[ottawafossil]

Hi forum, i have been collecting many nice (i call decent as a newbie) trilobite fossils from whitby shale in ottawa region (called billings formation here, whitby in southern ontario, utica in NY state i think). Anyway, the shale cleaves cery easily to reveal pygidia, midsections, heads, sometimes whole trilobites, usually small triatherus sp. they look good with lots of detail (photo) but after a week sitting, they get so fragile they crumble and crack when i handle them. What is the "best" way to keep these types of fossil so they will last and be strong enough to handle gently? Most do not need formal preparation as I can see much detail already and they are so small. So i just want to be able to strengthen the shale so they do not crack/flake/crumble. Also, some can be pyritized on occassion if this makes a difference.

[Bev]

Hi, I wish I could remember the name, perhaps someone here will mention it, but there is a water soluble product out there that hardens to protect fossils. Personally, I use Modpodge which I can get at any craft store and is also water soluble - gloss or mat finish. I use it primarily to keep my limestone fossils from shedding sand, but it does add stability. Any glue that dries clear will also do.

You may also consider "mounting" them on foam core board or wood for stability and display. Modpodge will act like a glue and a coating product. Most varnishes will do the same.

Hope this gives you some ideas at least.

[izak_]

I use Paraloid (http://www.workbenchdiary.com/2012/12/how-to-mix-weight-volume-paraloid-b-72.html) OR 10% percent pva glue in water. As in ten percent of the water used. Both work well.

Izak

[Fossildude19]

When you collect them, are they from a stream bed or other environment where it is always wet , or at least continually moist?

Sometimes, when they are constantly under water, or continually wet/moist, if they dry out too quickly, they can split or fall apart.

In such cases, wrapping the plates in newspaper, and allowing them to dry slowly, in a cool, dry place for a week or two will sometimes alleviate the degredation of the shale.

If I were you, I would try that method first, ... before getting into consolidants. It may save you some $$$.

Regards,

Edited September 4, 2015 by Fossildude19

[Taogan]

I transport and store shale in damp newspaper then use Paraloid on them anyway once I've cleaned the specimens. Seems to work so far.

[Ptychodus04]

I also transport the wet shale in damp newspaper and allow to dry slowly. Once dry, I use PVA dissolved in acetone of an acetone/polymer ratio of 40:1.

Works well without the extremely glossy effect that the PVA emulsions tend to have.

[Ridgehiker]

Nice specimen.

You may know but those were some of the first formations studied in Canada. You can go on line and look up old reports from the Ottawa Naturalist group back in the 1880's. It was great the way they continued the British tradition of dedicated amateurs doing a lot of the original exploring.

Good advice from others who mention not letting shales dry out too quickly. I will wrap specimens in newspaper and give the paper a light water spray for a few days. Every matrix is unique but I do the same with Oligocene graptolites, Eocene leaves, etc.

The worse people can do with shale is bring home specimens, wash them and then put them outside in the sun to dry quickly.

As for strengthening. I just use brush on avery diluted water based wood glue. Never had any issues over the decades. Some of this depends on your climate if dry, humid, etc.

If preparation, preservation, etc. is an issue then best to bring home some throw away pieces when out collecting. If worried about vibrations when cleaning or the look of a coating, then you'll have a piece to experiment on.

[Wrangellian]

Oligocene graptolites?

[ZiggieCie]

On damp material has anyone tried B-72 dissolved in alcohol?

Alcohol reacts differently with water than Acetone, and wondered if anyone has tried it. I don't have any of the damp shale or wet bone to try it on. If anyone has any of these it may be worth a try on a sample piece to see how it reacts. I have B-72 dissolved in both Acetone and water. The B-72 dissolves well in both. The B-72 in alcohol has more of a matt gloss sheen on my fossils than the Acetone witch has a glossy sheen.

Here is a link to a supplier I have bought from. http://www.conservationsupportsystems.com/product/show/acryloid-paraloid-b-72/acryloid

[Opisthotriton]

Acetone evaporates more quickly than ethanol, so if you want your B-72 to dry more slowly, which might be good for shale specimens, try the ethanol. Not just any drugstore rubbing alcohol, you specifically want ethanol. Not isopropyl. The purity of the ethanol can be a factor (some have a lot of water, and sometimes that can cause problems), but for price and ease of purchase, I would try the drugstore rubbing ethanol first.

Acetone hates water. Ethanol is water soluble (hence the adult beverage industry). So, if the fossil is a bit damp, ethanol could help the B-72 penetrate deeper into the specimen.

[Just_Liberty]

"Acetone hates water" ? Acetone is completely miscible with water at room temperature. Check any reference work in chemistry or an MSDS for acetone.