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GREEN RIVER FISH PREP


TOM BUCKLEY

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I've got a few Green River fish to prep and am having difficulty with the fins. I've prepped invertebrates before but haven't hit on the technique for these fish yet. I have a Paleo-Aro airscribe and an abrasive blaster, sodium bicarb and dolomite. The Paleo-aro seems too robust for the delicate fin rays and tends to damage a lot of them. I'm thinking of getting a micro jack but not sure of which # would be appropriate. I almost have my air-blaster up and running again. Is using sodium bicarb at a low pressure the answer? I know a couple of people who only use manual picks and have amazing results but, it is very painstaking. I've tried dental picks and am damaging more than exposing. Are dental picks too flexible? Is there anything just as thin but more rigid? Any assistance will be much appreciated. Thanks.

 

Tom 

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first things first.. are these from the split fish layer or the 18 inch?  The prep techniques for each are VERY different.

 

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1 hour ago, TOM BUCKLEY said:

Are dental picks too flexible? Is there anything just as thin but more rigid?

 

I've had good results with x-acto knives, with sharp new blades, but it is very slow, and I can't quite get the tiniest bits of matrix removed. I can't help with air abrasives. I enjoy the quiet of hand prep, and I can do it on my kitchen table. The knives work for me on both split fish and 18-inch layer slabs, but not on the hardest cap layer. I'm sure Kris and others will chime in soon. Good luck.

mike

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19 minutes ago, jpc said:

first things first.. are these from the split fish layer or the 18 inch?  The prep techniques for each are VERY different.

 

I'm not sure. How can I tell the difference?

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18 inch layer is slightly harder with a mixed beige/brown look to it. 

Here is one of Ptychodus04's fishes from the 18 inch layer.

 

5C80BAD9-927E-4067-BE23-3CB5EA77E845.thumb.jpeg.91ed11737d2f307218f9933200bf9e5f.jpeg

 

Split fish layer is more yellow-ish and much softer.

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18 minutes ago, Fossildude19 said:

18 inch layer is slightly harder with a mixed beige/brown look to it. 

Here is one of Ptychodus04's fishes from the 18 inch layer.

 

5C80BAD9-927E-4067-BE23-3CB5EA77E845.thumb.jpeg.91ed11737d2f307218f9933200bf9e5f.jpeg

 

Split fish layer is more yellow-ish and much softer.

 

So.....My Priscacara is from the 18 inch layer and the Knightia is from the split fish layer?

GRF 003.JPG

grf a 001.JPG

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Correct. :) 

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3 minutes ago, Fossildude19 said:

Correct. :) 

 

Thanks Tim. :thumbsu:

 

Tom

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3 hours ago, TOM BUCKLEY said:

I've got a few Green River fish to prep and am having difficulty with the fins. I've prepped invertebrates before but haven't hit on the technique for these fish yet. I have a Paleo-Aro airscribe and an abrasive blaster, sodium bicarb and dolomite. The Paleo-aro seems too robust for the delicate fin rays and tends to damage a lot of them. I'm thinking of getting a micro jack but not sure of which # would be appropriate. I almost have my air-blaster up and running again. Is using sodium bicarb at a low pressure the answer? I know a couple of people who only use manual picks and have amazing results but, it is very painstaking. I've tried dental picks and am damaging more than exposing. Are dental picks too flexible? Is there anything just as thin but more rigid? Any assistance will be much appreciated. Thanks.

 

Tom 

For the non-18 inchers, I use stainless steel dissecting needles and probes. No flex at all in them.

 

Another trick I use for GRF fossils is a bit of water to moisten the matrix. Usually by the time I have driven back a few states to home, my specimens are dried out. I found this can make the smaller and flatter fossils flake away too easily for my tastes.

Here's one I did a while back with nothing but peck and scratch and a bit of water:

image.thumb.png.20b707cc14aba56f976036600b9df8e7.png

 

A bit more on this with pics of the stuff myself and others around here use:

 

For the 18 inchers...well I haven't had the luck to gain any yet...but lots of airscribing on those by the pros.

 

 

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The fins are an outright nightmare. I go about them in a similar way with 18" and Split Fish specimens. If you touch them with a tool, they are done for. I use my Aro scribe to remove matrix (under microscopic magnification) to just above the fish. For Split Fish, I will dab a bit of thin paraloid onto any exposed fish and let it soak in and completely dry for a few minutes before going back to the spot.

 

You want to attack the fins with abrasive. Bicarb or dolomite work if you use a very small orifice and your pressures are insanely low. For split fish, we are talking 6-8 psi. 18" fish can take a bit more pressure but not more than 15 psi typically. You want to angle the nozzle of your abraider at as shallow of an angle as possible. The trick is pushing the abrasive across the matrix without it significantly impacting the fin. You'll know when you have the right angle as you'll be able to slowly remove matrix without the fins exploding or "burning" through. This takes time to learn and doesn't always work. Sometimes, the preservation just doesn't allow it.

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1 hour ago, Ptychodus04 said:

The fins are an outright nightmare. I go about them in a similar way with 18" and Split Fish specimens. If you touch them with a tool, they are done for. I use my Aro scribe to remove matrix (under microscopic magnification) to just above the fish. For Split Fish, I will dab a bit of thin paraloid onto any exposed fish and let it soak in and completely dry for a few minutes before going back to the spot.

 

You want to attack the fins with abrasive. Bicarb or dolomite work if you use a very small orifice and your pressures are insanely low. For split fish, we are talking 6-8 psi. 18" fish can take a bit more pressure but not more than 15 psi typically. You want to angle the nozzle of your abraider at as shallow of an angle as possible. The trick is pushing the abrasive across the matrix without it significantly impacting the fin. You'll know when you have the right angle as you'll be able to slowly remove matrix without the fins exploding or "burning" through. This takes time to learn and doesn't always work. Sometimes, the preservation just doesn't allow it.

I'll have to give this a try on my practice fish.

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17 hours ago, Ptychodus04 said:

The fins are an outright nightmare. I go about them in a similar way with 18" and Split Fish specimens. If you touch them with a tool, they are done for. I use my Aro scribe to remove matrix (under microscopic magnification) to just above the fish. For Split Fish, I will dab a bit of thin paraloid onto any exposed fish and let it soak in and completely dry for a few minutes before going back to the spot.

 

You want to attack the fins with abrasive. Bicarb or dolomite work if you use a very small orifice and your pressures are insanely low. For split fish, we are talking 6-8 psi. 18" fish can take a bit more pressure but not more than 15 psi typically. You want to angle the nozzle of your abraider at as shallow of an angle as possible. The trick is pushing the abrasive across the matrix without it significantly impacting the fin. You'll know when you have the right angle as you'll be able to slowly remove matrix without the fins exploding or "burning" through. This takes time to learn and doesn't always work. Sometimes, the preservation just doesn't allow it.

 

Thanks for the info.

Tom

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Many thanks to all who offered their advice and encouragement. I now feel well armed to go forth and hopefully not destroy too badly the intended fish,

 

Tom

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Those of you using Micro-Jacks from Paleo Tools......what # micro jack are you using? Thanks.

 

Tom

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18 hours ago, TOM BUCKLEY said:

Those of you using Micro-Jacks from Paleo Tools......what # micro jack are you using? Thanks.

 

Tom

I don't do much GRF but I have a microjack 3 for working on Oligocene rodents.  

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On 12/15/2020 at 4:13 PM, TOM BUCKLEY said:

Those of you using Micro-Jacks from Paleo Tools......what # micro jack are you using? Thanks.

 

Tom

I use a #4.

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