Tumido Prep Number 3

[Kosmoceras]

Very nice prep work.

I just wish some of the ammo preppers could be as careful...

Wrangellian, I don’t feel the two can be compared. They are in different types of nodule (speaking of composition) from different locations and depending on that, the shell flakes off differently from what is being prepared. Often it is just not possible as the shell is more firmly attached to the matrix than the ammonite itself.

[fossilized6s]

Doc Mud, you should post the finished prep in here.

A fantastic prep job on this guy from what I've seen in FOTM. Top notch, especially for only your third crab.

I can only hope to find my own crab nod and prep it. Hopefully l won't have to travel to NZ to do so, but it may be a welcomed vacation.

[Doctor Mud]

Doc Mud, you should post the finished prep in here.

A fantastic prep job on this guy from what I've seen in FOTM. Top notch, especially for only your third crab.

I can only hope to find my own crab nod and prep it. Hopefully l won't have to travel to NZ to do so, but it may be a welcomed vacation.

Thanks Charlie!

I posted the finished specimen last night in FOTM and time to finish the story here as well.

[Doctor Mud]

TA DA!!

Finally, after over 150 hours he is finished.

Since the last update I worked on the pincers the tips of the legs and the "business end" the eyes and spines.

Tricky work as the pincers are right there near the eyes.

To finish I did smoothing with a dremel and sharpened the shell rock interface with the Microjack to sharpen it up.

Could probably do with a bit more smoothing - but there is always something else that could be done.

I got really lucky in the split and all the bits were there.

After prep, I can see where two legs were just peeping out and I didn't notice in the field. I don't feel bad though, one was just a tippy tip and the other wasn't so obvious. I felt better lugging this guy out over km of boulders knowing exactly what was inside.

My next one is going to be my smallest conc. yet. 5 cm across which is a tiddler as far as Tumidos go!

[Wrangellian]

Very nice prep work.

Wrangellian, I don’t feel the two can be compared. They are in different types of nodule (speaking of composition) from different locations and depending on that, the shell flakes off differently from what is being prepared. Often it is just not possible as the shell is more firmly attached to the matrix than the ammonite itself.

I knew I'd be shot down for saying that...

But didn't Dr Mud's crab present the same sort of flaky shell problem as you speak of, and how many ammo preppers spend 150 hours on a specimen? I gather that no one cares to spend that long because it's 'just an ammonite' and there are 100s-1000s of them.

[Doctor Mud]

Thanks for the high praise for my efforts Wrangellian!

The thing that takes the time with these large nods is the amount of rock to be removed. I think I'll invest in a minijack or something to speed up bulk removal - like RB does.

Things might speed up a little with experience and an air abrader might help with that flaky shell issue. I tend to be very cautious - more so as the piece progresses as so much time has been invested. One miss placed scribe stroke can mean disaster!

I wouldn't say I'm better or more patient than anyone else and I know that everyone strives for the best that they can to get the best out of their fossil. I think your right though when you say that more effort might be put into crabs - even incomplete ones since they are rarer. That's coming from a non-ammonite person though and I'm sure there are the Tumidos of the ammonite world where every specimen - even an incomplete one is prepped like a brain surgeon

I guess its an effort - reward calculation we sub-consciously make. Take a look at all the effort I out into what I would consider now to be a "crab cobble". It was the best Tumido I had and didn't know if I could get another.

Edited February 28, 2015 by Doctor Mud

[Doctor Mud]

I wonder if the issue for this crab is slightly different than the problem Kosmoceras described?

The problem with some crabs is that the shell can be a little soft in places and although the rock with come off the shell can be pulverised if it is prepped too aggressively.

These are called "softies" I've found that otherwise robust crabs can have soft areas, and the top of the carapace seems to be a common area. Perhaps a mineralisation issue?

You just have to turn the scribe way down and switch into what RB calls prep and glue mode (Beast Mode will definitely not work).

Sounds like the ammonites have a different problem where the outer layer of shell adheres more to the matrix than to itself and the matrix won't flake off nicely. This does also happen with crabs and these get called "sticky" crabs. You almost have to grind down or abrade to the shell surface rather than have it flake off. At least with the crabs I suspect this is due to mineralisation at the shell rock interface and the composition of the shell is very similar to the matrix. This means that the two don't want to easily separate.

That's my two cents after only three crabs though!

Edited February 28, 2015 by Doctor Mud

[Wrangellian]

Yes, I guess there is a range of stickiness or softness to the shell with ammos as well as with crabs, but I think (speaking for what it's worth as a non-prepper) anything is possible with the right amount of care, time and the right equipment. I just don't think you see as much of these put into ammonites (with some exceptions) as you do with crabs and trilobites. I have seen a few good examples of prepping even on those Yorkshire Dactylioceras ammos but I wonder if those are flukes or if they had more care put into them. It seems like people (not naming names) are just barreling through, cleaning off all the shell down to the inner mould and showing them off anyway... Maybe they hope the next one will be an easier/more cooperative one that will respond better to the rushed technique? Again I can't speak from experience but your 150 hours of effort and carefulness has certainly paid off and deserves praise even though you may not have much experience. Apparently you don't need hundreds of hours of experience to get good results, even with crabs, though I don't mean to downplay experience and you can only get better with more of it. You are not an ammo guy but I'd like to see what you could do with one of my ammos in hard matrix...

Edited March 1, 2015 by Wrangellian

[fossilized6s]

I don't want to hijack this thread at all, but i know depending on where the ammonite is found they can be steinkerns and will not take a prep.

[Doctor Mud]

No worries Charlie,

That's what TFF is all about. Open discussion about everything fossil!

Yes - with all fossils there is a wide variety of preservation types and if it is a steinkern, no amount of prep. magic could put the shell back on.

Interesting tangent we ended up going on here. Its got me curious to try an ammonite now! I bet there are all sorts of challenges I haven't even imagined - the surface topography for one, ribs and spines. I bet spines could be a nightmare!

I've got a Miocene nautiloid to try and this might be a nice intro to the world of cephalopod prep.

Edited March 1, 2015 by Doctor Mud

[Wrangellian]

I don't want to hijack this thread at all, but i know depending on where the ammonite is found they can be steinkerns and will not take a prep.

The ones from Yorkshire are not steinkerns, they have their shell still.

I'll be interested to see what you can do with the nautiloid, Dr, and if you'd like I have a Yorkshire ammo I could send you to try!

I did not mean to hijack either, but that tends to happen when I say something controversial....

Back to the originally scheduled program!

[Ludwigia]

The ones from Yorkshire are not steinkerns, they have their shell still.

I beg to differ. The majority of them are pyrite steinkerns from which the shell has sprung away. It's not so often that the shell comes out of the concretion in one piece.

[Wrangellian]

I beg to differ. The majority of them are pyrite steinkerns from which the shell has sprung away. It's not so often that the shell comes out of the concretion in one piece.

So you're saying that even if someone spend the kind of time and care on one of these that Dr Mud spent on that crab, they could still not prep it and leave the shell intact?

[Ludwigia]

No I'm not saying that.

[Auspex]

The aragonite of ammonite shells and the chiton of crab exoskeletons are very different in chemistry and structure; I would expect them to be very different from one another after diagenesis and to behave differently during prep.

[Wrangellian]

Be that as it may, if people don't put the same kind of time/care into the ammo as the crab preppers put into the crabs, they aren't going to get as nice a result as if they did, right? Have any crab preppers had any experience with ammos, specifically the Yorkshire Dacs? If I heard it from someone who did, I would be satisfied. But I don't want to hijack this any longer than I already have, maybe it deserves a separate thread if there is any more to say.

[fossilized6s]

Here's a Crab next a Yorkshire Ammo before and after prep. Looks good to me.

http://www.thefossilforum.com/index.php?/topic/50955-november-2014-invertebrate-plant-find-of-the-month/?hl=%2Byorkshire+%2Bammoniteyorkshireammonite

[Kosmoceras]

Be that as it may, if people don't put the same kind of time/care into the ammo as the crab preppers put into the crabs, they aren't going to get as nice a result as if they did, right? Have any crab preppers had any experience with ammos, specifically the Yorkshire Dacs? If I heard it from someone who did, I would be satisfied. But I don't want to hijack this any longer than I already have, maybe it deserves a separate thread if there is any more to say.

Agreed, a separate thread might be good. And yes, I do think they come out at a higher quality with more time, a lot of them have been poorly prepared with too many prep marks. With the shell maintained though, not so much.

Just want to add, Mike Marshall is among the top fossil preparers in the UK. No doubt more time is put into his work (alongside with his experience and skill), yet his dacs are still missing shell.

Edited March 3, 2015 by Kosmoceras

[Wrangellian]

I suspect he doesn't spend as much time as he could, because he's 'in the business' and doesn't find it economical to prep every one that carefully (not that he doesn't know how to make a shell-less ammo look good - they look very nice and that's enough to make people buy... apparently it's just me who wishes he could see more with shell and I would pay more money for such a one if I had the money..), but again, I don't really know!

Maybe the mods can split this off in a separate thread for us?

[Doctor Mud]

Maybe the mods can split this off in a separate thread for us?

I have no problem with this interesting, and obviously slightly controversial discussion staying here.

Then there is continuity for later readers so they can see how this discussion evolved.

An alternative - and maybe a way to involve more members in the discussion would be to peel this bit off and re-title it to make it easier for preppers to pick up on the content. With a note and link to this thread as the point of origin.

I'm fine either way.

[Ludwigia]

The great obstacle in achieving the effect which you desire is the fact that the overwhelming majority of the ammonites in the Whitby concretions have their separating layer between the shell and the mold. The outer side of the shell is on the other hand firmly cemented to the outer matrix of the concretion. When you use a hammer to "crack the nut", then the shell almost invariably gets sacrificed in the process, unless you've managed to get one of the rare lucky splits. Obviously then, if you want to try to preserve the shell, you need to spend hours and hours scribing at low pressure getting down as close to the shell as you can, and then doing the rest with the abrader, which also takes a long, long time, since the matrix is quite hard. The difficulty however even by this method often arises, that the separation layer is so sensitive that even the light pressure can cause parts of the shell to suddenly spring away. Then you need to glue it back on in the hopes that it doesn't happen again if you have had the luck to find the bit that has just flown through the air. So even with this method, good results are not guaranteed. I'm speaking from experience.

Edited March 3, 2015 by Ludwigia

[Auspex]

There are a bunch of highly experienced, highly skilled preparators of ammonites here, and I do not think that what you deem 'inferior results' are from expedience toward a lesser goal. The circumstances of the specimen's preservation will determine what is possible, and extraordinary efforts to circumvent the loss of shell are fruitless (short of artificially recreating one, which result would be unnatural).

[6ix]

Wow Dr Mud - thats come out fantastic and got me itching to get back to my one!

Is there any reason you didnt expose more claw? I guess its because they will angle back towards the mouth too far.

Congrats man, you gotta be proud!

[Doctor Mud]

There are a bunch of highly experienced, highly skilled preparators of ammonites here, and I do not think that what you deem 'inferior results' are from expedience toward a lesser goal. The circumstances of the specimen's preservation will determine what is possible, and extraordinary efforts to circumvent the loss of shell are fruitless (short of artificially recreating one, which result would be unnatural).

Eloquently expressed Auspex (as usual )

Given the passion for fossils and ingenuity of our members I would expect preppers with the time and means to give it their best shot at producing the best specimen.

It seems (like Ludwigia said) that preservation might be an issue preventing the presence of shell on some specimens and this is the reason some ammonites don't have a shell.

Edited March 5, 2015 by Doctor Mud

[Doctor Mud]

The great obstacle in achieving the effect which you desire is the fact that the overwhelming majority of the ammonites in the Whitby concretions have their separating layer between the shell and the mold. The outer side of the shell is on the other hand firmly cemented to the outer matrix of the concretion. When you use a hammer to "crack the nut", then the shell almost invariably gets sacrificed in the process, unless you've managed to get one of the rare lucky splits. Obviously then, if you want to try to preserve the shell, you need to spend hours and hours scribing at low pressure getting down as close to the shell as you can, and then doing the rest with the abrader, which also takes a long, long time, since the matrix is quite hard. The difficulty however even by this method often arises, that the separation layer is so sensitive that even the light pressure can cause parts of the shell to suddenly spring away. Then you need to glue it back on in the hopes that it doesn't happen again if you have had the luck to find the bit that has just flown through the air. So even with this method, good results are not guaranteed. I'm speaking from experience.

Sounds like a nightmare!

At least with soft crabs there is usually matrix inside right up to the shell and gentle prepping and consolidation may help. That being said, sometimes there are voids with no matrix inside crabs. Don't want to jinx myself....but haven't seen one of those yet.

I wonder why the shell is easier to separate from the internal mold than the matrix?