How do I protect carbon-film fossil on shale?

[tombk]

Hi all, I’m excited to be going on a field trip with a a group in Illinois (ESCONI) later this month to a site that has a huge mound of mined-up Pennsylvanian shale. There may be some carbon-film plant impressions there. I’ve never collected this type of fossil before, and I’ve heard that carbon films can disappear quickly when exposed to the air. 
 

My question is should I bring something to coat this type of fossil? And if so, what? In doing some research, I see that some people recommend spray-on Krylon while others recommend against it. Would brushing on a thin coat of Paraloid do the trick? (I’ll check with some members from ESCONI, but it’s a new site for them, and their material says that there is a lot they have yet to learn about preservation of specimens from this location.)

 

[JimB88]

Not all carbon films require it, but I have heard of people using hairspray as a fixitive. You should ask the folks in ESCONI if anything is needed.

 

[connorp]

@tombk I am happy to talk about this site with you, but via PM only.

[Bguild]

With the Carboniferous plant imprints I find, I haven’t needed to apply anything right away. I do however paint them with a PVA solution back home when I have a chance. Would recommend to help preserve them long term, but I wouldn’t think you need anything in the field. 

[RJB]

When I first started digging plant material I would spray the intire rock with some kind of spray to seal it.  I quit doing that after some time and started applying my glyptal solution to the plant matter only.  I didnt like the shine on the rock.  Ive got examples if you'd like to see some.

 

RB

[tombk]

5 hours ago, RJB said:

Ive got examples if you'd like to see some.

I’d love to see some samples. 

[RJB]

19 hours ago, tombk said:

’d love to see some samples.

Here ya go. 

 

RB

 

Here is a rather large poplar type leaf that is in need of some help. 

 

Here is the same leaf with the stem uncovered but you can see how my glyptal made the leaf 'POP', but more importantly it protects that super thin layer of plant material.

 

My youngest son found this when he was 8.  Here you can see the shine from the spray acrylic i used to use.  I do not like the shine at all.

[tombk]

Thanks for the photos! I definitely agree that the pop of the glyptal beats the shine of the acrylic spray. Uncovering the stem must have been delicate work. Did you use an air scribe to do it?

[Crusty_Crab]

I think the best rule to follow is to not apply any overcoats unless absolutely necessary. The reason why is that these fossils have persisted for millions of years without human intervention. What does human intervention add? Applying an overcoat will actually make any molecular studies in the future more difficult. Degradation usually follows because we have removed it from its context, such as exposing it to an oxidizing atmosphere. In that case, an overcoat protects it from the oxidizing atmosphere. In that case, you have to make sure the overcoat is 1. Stable, and 2. won't discolor over time. Commercial sprays such as the Krylon are avoided because we don't know what's in the mixture and how it will react over time. 

Some of the common overcoats that are used are Paraloid B-72 (ethyl methacrylate co-polymer) or polyvinyl butyral (Butvar B-76 or B-98) or polyvinyl acetate are better studied. I like Paraloid B-72 since to date, it appears to be stable and there are no known examples of it discoloring. My experience with cyanoacrylate (super glue) is that it discolors very quickly into a yellow color. 

 

In short, I would do nothing. If it becomes apparent that you absolutely have to do something, I would start with B-72 and experiment. 

[Wrangellian]

15 hours ago, RJB said:

Here ya go. 

RB

Here is a rather large poplar type leaf that is in need of some help. 

Here is the same leaf with the stem uncovered but you can see how my glyptal made the leaf 'POP', but more importantly it protects that super thin layer of plant material.

 

My youngest son found this when he was 8.  Here you can see the shine from the spray acrylic i used to use.  I do not like the shine at all.

 

I agree, the shiny coatings are not so attractive and make the thing look like a plastic cast, and difficult to photograph without the glare, too.

I like the results of your glyptal, Where do you get the stuff and how is it applied? Is it difficult to precision-apply to only fossil only, and what would it look like if you coated the whole rock?

[RJB]

20 hours ago, tombk said:

scribe to do it?

ME9100 from Paleo Tools.

 

7 hours ago, Wrangellian said:

like the results of your glyptal, Where do you get the stuff and how is it applied? Is it difficult to precision-apply to only fossil only, and what would it look like if you coated the whole rock?

I bought my quarts of Glyptal many years ago and easily have enough to outlast my lifetime.  My youngest son will get whats left when Im gone.  I dilute it with acitone and apply with whatever size of small art brush that seems suitable to me.  I carefully apply it onto the fossil being careful not to create any puddles. 

 

RB

 

 

[Wrangellian]

So it's a type of varnish, or what? I see on the Glyptal website they have a whole range of products.

[Megalodoodle]

On 9/9/2021 at 7:59 AM, Wrangellian said:

So it's a type of varnish, or what? I see on the Glyptal website they have a whole range of products.

I believe you are looking for this product? http://www.glyptal.com/products/9620tech.pdf