Leaf imprint prep. questions

[terfezia]

Hello everyone,

Just joined this place and cant wait to get aquainted. I have a few questions regarding a large (15 kg) slab of oligocene sandstone containing large numbers of leaf imprints which are in pretty good condition. Iam still debating if i should split a few more layers from the slab to expose more leaves and pick the best ones for preping or if I should leave the slab as it is and just clean the already visible leaves. I only have a hand held manual tools for the job. We do have an electric turbine though with lots of different driling and polishing bits which might be of use.

Are there any safety measures I can take before going about doing this? Iam thinking of things like spraying the surface with sugar water to stabilise the imprints and the surface rock.

Is there any other substance I can use to coat the end product to make it a bit more long lasting? This rock seems like something that will crumble away over time.

What do you guys think?

Close up of the top left corner

Picture (a bad one at that) of the whole slab. Leaves on both sides and obviously even more in the inner layers.

Edited January 7, 2016 by terfezia

[Ptychodus04]

Welcome and well done on the find.

The sandstone looks to be very loosly cemented so I would not recommend attempting to split it. You will probably just end up with a bunch of crumbs!

Without access to an airscribe, I would use a dental pick to remove loose bits of matrix and a small hammer and a nail to remobe larger bits that are covering any of the leaves. In order to consolidate the slab and preserve it, the best materials are PVA or Butvar. They are museum conservation grade plastics that can be dissolved in Acetone or Alcohol and applied to the specimen.

[ZiggieCie]

That is a very nice specimen. I would suggest that you save that, "indoors" and find other similar pieces to practice on. This way you would get an idea of how the material responds to cleaning and opening up the fossils.

The preservatives Ptychodus04 mentions are very inexpensive and can be found here. ( http://www.conservationsupportsystems.com/product/show/acryloid-paraloid-b-72/acryloid )

Some instructions here.

http://www.connectingtocollections.org/wp-content/uploads/2014/02/Davidson_and_Brown_2012_Paraloid_B-72-_Practical_tips_for_the_vertebrate_fossil_preparator.pdf

Waiting to prep a good specimen till you would have more experience, never hurts. It has been sitting around for hundreds of millions of years and can be ruined in seconds. We have all been there.

Welcome to the forum.

[Ptychodus04]

Great advise Ziggie.

[Auspex]

Your specimens are beautiful, and fascinating

Please do not put sugar water on them; this will cause more harm than good. If you cannot get the professional conservation materials, hair spray will help bind the surface, but only against light handling.

[terfezia]

Welcome and well done on the find.

The sandstone looks to be very loosly cemented so I would not recommend attempting to split it. You will probably just end up with a bunch of crumbs!

Without access to an airscribe, I would use a dental pick to remove loose bits of matrix and a small hammer and a nail to remobe larger bits that are covering any of the leaves. In order to consolidate the slab and preserve it, the best materials are PVA or Butvar. They are museum conservation grade plastics that can be dissolved in Acetone or Alcohol and applied to the specimen.

Thanks Ptychodus ill look into these materials. The slap has some thickness to it but your right about it being fragile. Furthermore the layers arnt well defined. The surface you can see here is actually the freshly exposed face of half of the original block. Ive found the original seam this block came from though. Its from an old clay mine beside Budapest, Hungary. Ive got plenty of material to practice on. Ive got a few smaller pieces from the other half which look reasonably good.

By the way back to these stabilising agents, is there anything less volitile I could use?

That is a very nice specimen. I would suggest that you save that, "indoors" and find other similar pieces to practice on. This way you would get an idea of how the material responds to cleaning and opening up the fossils.

The preservatives Ptychodus04 mentions are very inexpensive and can be found here. ( http://www.conservationsupportsystems.com/product/show/acryloid-paraloid-b-72/acryloid )

Some instructions here.

http://www.connectingtocollections.org/wp-content/uploads/2014/02/Davidson_and_Brown_2012_Paraloid_B-72-_Practical_tips_for_the_vertebrate_fossil_preparator.pdf

Waiting to prep a good specimen till you would have more experience, never hurts. It has been sitting around for hundreds of millions of years and can be ruined in seconds. We have all been there.

Welcome to the forum.

Thanks ZiggiCie,

I dont even have to look for it

The subject has been indoors and so far so good. The drying hasnt really done any damage it seems.

Practice makes perfect and Iam in great need of it. An airscribe is on my wishlist too. But for now some basic dental tools and that turbine I mentioned will have to do the job. Ill post some pictures of my progress.

[RJB]

Ditto, Ditto and ditto

RB

[terfezia]

Your specimens are beautiful, and fascinating

Please do not put sugar water on them; this will cause more harm than good. If you cannot get the professional conservation materials, hair spray will help bind the surface, but only against light handling.

Thanks Auspex,

I will by no means put sugar water on it. Remember reading such instructions somewhere in the distant past. Ill see if I can get a hold of the above mentioned materials instead.

[Ptychodus04]

By the way back to these stabilising agents, is there anything less volitile I could use?

Actually, volatile is what you are looking for in a carrier for the plastic. It penetrates deeply and evaporates quickly.

Some collectors water down white glue which is actually a PVA emulsion. This is less volatile and is common practice for wet specimens but is not recommended for dry specimens as it is VERY difficult to remove if needed in the future.

[terfezia]

Actually, volatile is what you are looking for in a carrier for the plastic. It penetrates deeply and evaporates quickly.

Some collectors water down white glue which is actually a PVA emulsion. This is less volatile and is common practice for wet specimens but is not recommended for dry specimens as it is VERY difficult to remove if needed in the future.

Understood. Ill go through the instructions and decide on a solution. I actually checked on the smaller fragments yesterday and the drying isnt doing too much good to the specimens. The imprints are fading somewhat after only about 2 weeks. They are kept in the garage, about 5-10 celsius.