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Questions on Knightia Prep


Sagebrush Steve

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When I was at the Tucson fossil show I picked up several slabs of unprepared Green River fish from the 18-inch layer.  I've been working on this Knightia and have a few questions.  I only have hand tools so I have been carefully removing matrix using some pin vises with various needle tools I picked up from PaleoTools.  Here's how it looks so far:

5ad186b372bb9_fullbodysmall.thumb.jpg.cf894fb4b70744174692ac54d9494b77.jpg

 

First question:  If you look in the areas of the anal fin and the dorsal fin, there appear to be random swatches of organic material not associated with the body.  Perhaps these are regions that "blew up" as the fish was decomposing.  Should I be removing these and trying to restore the original outline of the fish or should I leave them alone?  For example, here's a closeup of the dorsal area:

 

5ad187776cd44_DorsalFin.thumb.jpg.7079abfcfdeada5ea9d67f14b890e26d.jpg

 

Next question.  It's been difficult to remove all the last bits of matrix with needle tools.  The photo below shows the bits of matrix remaining in areas around the backbone.  I don't think I can do much more on it with needles.  Would it help if I were to invest in something like a Paasche AECR air abrasive tool or should I stop here.  I would need a compressor, blast cabinet, and all the paraphernalia if I were to do this, but if it would help I might consider it.

 

backbone.thumb.jpg.12cb0003f68c06edb05d4a9debc14889.jpg

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@Sagebrush Steve   I think youve got some scales beyound your fish outline.  and yeah, in my opinion an air abrasive system would work out great for these fish in harder rock.  I myself try and not go beyound the outline of the fish.  Here is an example.

 

RB

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Hi, Steve! 

I reckon that's a darned good job with only pins and things. :)

Life's Good!

Tortoise Friend.

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I would guess the same - disarticulated scales and bones due to "explosions" of decompositional gasses.

Air abrasion would do the trick, just be aware of the possibilities of the air blowing off scales or bones.

I'm not sure that is an issue with the 18 inch layer material as much as the sandwich (split fish) layer material.

 

Looking good so far, Steve. Thanks for sharing your progress with us. 

    Tim    -  VETERAN SHALE SPLITTER

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I agree with the above that you have some random scales etc there. I would not try to remove them or prep them. Just leave them as they are at this point.

 

An abrasive system will work wonders but is a big investment. You can also hit the specimen with a gum eraser to help remove more fine matrix. Then a layer of really thin PVA/Paraloid/Butvar (50:1) over the whole specimen will disguise some of the leftover matrix by darkening it.

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