Advice On Prep'ing Fish Fins

[JasonH]

Hello all. This is my second post, so still a noob. I'm very happy to have found this forum to help learn about fossils and preparation - I've already read a lot of very helpful information.

I've recently purchased and prep'ed my first fossil - a prisca from the green river formation. It was a lot of fun and good practice. I then purchased a large Diplo and have started working on it. So far the diplo (which is much larger) seems more delicate - fine bones and very thin tissue between the bones (ribs?). But so far so good.

The only area on the prisca that didn't turn out great (for a first attempt) was the fins. And when I say not great, I mean really, shamefully bad. They are so delicate and fine that by the time I got to the tips, I was regularly scraping them off while trying to scrape off the matrix - even while being very careful. I never got to the fine, almost hair-like splits of the end of the fins.

As I start on the Diplo - I've reached the point that I need to address the fins. I really don't want to screw up the fins on this one - I'm really hoping it will be a display fossil.

I'm using a pin vise and carbide tip (from Paleotools) and I'm using a magnification visor (2.5x I think), so I have a good view when I blow it. If better tools will help, I'm open to that. But I have a feeling it's the user, not the tools. I can't imagine a vibrating tool like a dremel or scribe doing better on the delicate fins.

Any advice? I've tried using a gum eraser - and that works if there's just a haze of film left, but doesn't seem to take off a layer. I've also tried using vinegar to weaken the matrix. That also seems to help, but not solve the problem - and I worry it will weaken the fossil.

Thanks for any input/guidance.

Jason

[Auspex]

This won't be the whole answer, but keeping the tools really sharp will help.

[Xiphactinus]

I've used an X-acto knife on the Green River fish fins with pretty good results....like Auspex said...really, really sharp tools and patience. Don't try to take too much off at once.

[Boneman007]

I've used an X-acto knife on the Green River fish fins with pretty good results....like Auspex said...really, really sharp tools and patience. Don't try to take too much off at once.

Words of wisdom!

[JasonH]

Very interesting. I had actually thought the opposite - that a more dull tool would prevent me from 'slicing' down through the fin - and intentionally delayed sharpening. Okay then, back to the wet stone.

Thanks very much for taking the time to offer me some advice.

[siteseer]

I was at the Tucson shows early this month. To show the process and pass the time, a Green River fish dealer (Ulrich's) was cleaning a Priscacara ("18-inch layer") with some kind of eraser. In fact he was selling kits that allowed you to clean your own. A kit with a Diplomystus was $20-25 and a kit with a Prisca was $50. I think the necessary tools are included with the price.

Hello all. This is my second post, so still a noob. I'm very happy to have found this forum to help learn about fossils and preparation - I've already read a lot of very helpful information.

I've recently purchased and prep'ed my first fossil - a prisca from the green river formation. It was a lot of fun and good practice. I then purchased a large Diplo and have started working on it. So far the diplo (which is much larger) seems more delicate - fine bones and very thin tissue between the bones (ribs?). But so far so good.

The only area on the prisca that didn't turn out great (for a first attempt) was the fins. And when I say not great, I mean really, shamefully bad. They are so delicate and fine that by the time I got to the tips, I was regularly scraping them off while trying to scrape off the matrix - even while being very careful. I never got to the fine, almost hair-like splits of the end of the fins.

As I start on the Diplo - I've reached the point that I need to address the fins. I really don't want to screw up the fins on this one - I'm really hoping it will be a display fossil.

I'm using a pin vise and carbide tip (from Paleotools) and I'm using a magnification visor (2.5x I think), so I have a good view when I blow it. If better tools will help, I'm open to that. But I have a feeling it's the user, not the tools. I can't imagine a vibrating tool like a dremel or scribe doing better on the delicate fins.

Any advice? I've tried using a gum eraser - and that works if there's just a haze of film left, but doesn't seem to take off a layer. I've also tried using vinegar to weaken the matrix. That also seems to help, but not solve the problem - and I worry it will weaken the fossil.

Thanks for any input/guidance.

Jason

Edited March 1, 2012 by siteseer

[squali]

I really enjoy prepping the green river plates.

The main thing that I have found is to work in short intervals.

It keeps me from becoming inpatient and lets my hand rest.

[Blastoid]

Get higher magnification. I use a low power binocular microscope on a long boom so I can prep 2' wide plates. That and good lighting = super fun fish prep. More mag means you can pay attention to the varves, the light-dark layers of deposited rock. Quite often you'll be able to zip down to a distinctive varve, just above the bones, with power tools, then go nice and slow from there. This doesn't work so well on the skull, where you get big bones poking out, but it's awesome for the rest of the fish.

Extreme patience is required... an hour's work means just about nothing. If coffee makes you jumpy, don't drink it before prepping, you need to be nice and mellow. Use a comfy chair with good back support, keep your forearms horizontal and feet flat on the floor; if you can. Pay attention to ergonomics! Try to avoid repetitive strain injury. Carpal tunnel is teh suxxor... it's the gift that keeps on giving, and can annoy you for years. Stretch, and/or throw a ball around for a few minutes every hour. Some doctors now suggest that sitting for 4 hours without exercise is as bad as smoking

Vary your angle of attack. Scrape along the fish, at a low angle, for the most delicate bits. Drop your needle to a lower angle, more parallel to the plate.

Perhaps graduate to finer tungsten carbide rod, which will make finer tips, but will also break more easily. I don't grind mine round, like a pencil, but flat, like a syringe, a nice long flat. Achieved very quickly with a diamond hone, which are now easy to find and cheap, but get a flat one, not one with the holes, if you can. (Ditch the oil stone!) Hone the edge regularly; considering how soft this matrix is, and how hard the tungsten carbide is, it's really surprising how quickly it dulls. When you find you're polishing the stone instead of scraping it away, and your hand is cramping from the force required, stop and sharpen.

Occasional blowouts will still happen, and I don't think anybody's prepping the entire fins to perfection, the finest ray ends are thinner than paper and you're thru them in a blink.

End product is worth the work, a 55 million year old fish that you know is the real thing... no paint, no filler, no glue, no touchups... which, in the fossil world, is rare as hell.

A $10 air pump from your local tropical fish shop is great for dust removal, canned air is great stuff too. A dust collector will keep you safe from a slow and grisly death via silicosis.

When hand tools get old, graduate to a compressor, air scribe, and then air abrasive, which allow you to work 10x faster without the hand pain. These tools are fricken awesome fun, the rock just melts away... worth every penny.

The gum eraser is for final cleaning, not serious removal. It just darkens the bones and shines them up a bit, by removing the last traces of matrix.

I'd suggest avoiding vinegar, there's no need, and you may cause problems down the road.

I'm almost done my 18" Notogoneus, done entirely by hand. Only thirty plates to go after that!

Have fun with your diplo!

B

[Pagurus]

Thanks, "Blastoid", for your terrific prepping tips. Everyone on this forum is so helpful.

[old dead things]

All of the above posts give you a lot of good ideas for prepping your fish. We prep a lot fish every year (see www.olddeadthings.com). For some of that fine detail work we use a fiberglass pen. Try widgetsupply.com Go to Hobby tools, then utility for the scratch brush. Be sure to use the fiberglass one not the brass or steel.

We will use three or four a year, but one brush will usually clean 100 plus fish. We bought several hundred brushes five years ago and at that time each brush came with a refill, so you may want to check that too. It's a great item. Anyway try one, they are relatively cheap and as with everything else the more you buy the cheaper they get. They use to be marketed in Germany under the name Ecobra.

They work best on the fish from the Green River split fish layer. I don't know that we have ever tried them on the 18" layer, but imagine it would work there too.

Jim

Old Dead Things

[JasonH]

Wow - again, fantastic advice and suggestions. I can't thank you guys enough for taking the time to provide such detailed guidance.