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Spence Shale Trilobite Prep


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Recently collected these trilobites at Spence gulch along with a few more.  The all seem very fragile.  1st picture is of the trilobite and second is the cast.  Anyone experienced with these and have any ideas about what to do to prep from here?  I am concerned about doing more damage than help and was just considering putting a light coat of PVA on them as is. 


I think these are Amacephalus but not sure what species.



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Thanks for your response.  I have used PVA for years but did research on the Paraloid B-72 and this seems like a much more appropriate materials for bonding/coating as you suggested. Seems like it is the material of choice for conservation type of work.  


A couple of questions.  Seems like it can be thinned with a number of chemicals (acetone, & toluene for example). What are using?  Second, does it leave a shiny surface when thinned as you suggested?

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Don't use toluene, it's too toxic.  B-72 is more soluble in acetone, but ethanol works too.  Acetone evaporates much faster, which may make it harder to work with for some purposes such as a bonding agent, as you have less time to get pieces into the right contact.  However it's fine for that use as long as you know to work quickly.  Also acetone absolutely needs a well ventilated work area.  If the finish ends up a bit too shiny, you can briefly dip the specimen in acetone to remove some of the excess surface coat.



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What Don said. :) one thing I will say is a mix of ethanol (it's difficult to get Paraloid to dissolve just in ethanol) and acetone. Using acetone alone can cause 'skinning' as it evaporates so quickly. You can either do what Don suggested or with a lint free rag and a little acetone just dab the surface. In my opinion over-glossy fossils look a bit rubbish. 

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