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Gluing an Ammonite for Prep Questions


Calli99

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Hi everyone,

 

I went fossil hunting on the Yorkshire Coast a few days ago and picked up plenty of Dactylioceras ammos but not much else. Among them are these two which both cracked after an exploratory 'tap' with the hammer. I have never glued broken ammonites together for prep before but have seen it spoken about a lot. I have a few questions about how to approach this.

 

Firstly, do you think these specimens are viable? The other issue is that I only have a Dremel to prep with so even if I glue them back together there will be an awful lot of matrix to remove..

 

Where do you apply the glue? On the whole surface of the broken fragment including the matrix, or just the fossil?

 

Is there anything to look out for when prepping a glued ammonite?

 

Which side of the ammonite should I prep from once glued? For the smaller ammonite, most of the specimen is on the smaller half of the rock, so obviously I would rather prep from that side in, but would going from the other side be preferable?

 

I'm not sure I've made much sense here so please tell me if I've just spouted some nonsense!

 

Ammo 1

IMG_8299.thumb.jpeg.367e248c31a2b79df43b7430cf99c0a0.jpeg

 

IMG_8285.thumb.jpeg.82f5a68d7748f98848e118b39790a092.jpeg

 

IMG_8286.thumb.jpeg.63db11dc2f490b32fa2d7f6abe7075b3.jpeg

 

Ammo 2

IMG_8287.thumb.jpeg.f373d44b48761232c4484a985a9295c8.jpeg

 

IMG_8288.thumb.jpeg.4ea9806ac5841dfba8bdf9e300d56e22.jpeg

 

IMG_8291.thumb.jpeg.0bf618fdcf595003999448ec539c521f.jpeg

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8 minutes ago, Calli99 said:

Where do you apply the glue? On the whole surface of the broken fragment including the matrix, or just the fossil?

Those are all great questions! 

When I’m gluing a fossil for prep i only apply the super glue to the fossil itself. Making sure i get all the way to the edges. And making sure both pieces are as clean as possible. A little grit in there will make a big difference to the fit.. While using the dremel periodically check to make sure the original crack or other hidden cracks don’t start opening up. I have an adjustable electric engraver so i will use the lowest setting that allows me reasonable progress. I also either hold the piece or rest it on a foam pad while prepping so it help deaden the vibrations. Starting from any side should be fine but knowng me on that multi ammo block i’d be trying to see what else is in there first! LOL! Good luck and can’t wait to see how it comes out!

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When it comes to glue, in many cases less is more. After cleaning both halves, apply as thin a coat as possible (one trick is to give it a good puff of air to spread it), press the halves firmly together, and then wick glue along the crack, carefully removing any excess immediately. You'll then want to clamp it tight to allow for curing. To be on the safe side, 24 hours should do it. :) 

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...How to Philosophize with a Hammer

 

 

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Thank you both for your answers! :D

 

I have medium viscosity superglue to hand, do you think that will do the trick? I'm going to order myself a G clamp and will glue as well if needed. 

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Like RandyW has mentioned, you dont want any grit.  Very important that one.  One little grain of sand will make for a 'not so good' fit.  A practice fit is always a good idea.   Also, I'm one of those that glues the rock too.  Not in all cases, but usually and thats just to help hold things together.  You can always prep past the glue.  Best of luck

 

RB

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If was me I also glued the matrix too as Ron has just said this maybe give more strength and leave you to prepare it how ever you like. Definitely clamp it this will both will squeeze any unwanted glue out of the way of join and make it a lot stronger. 
 

cheers Bobby 

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I would recommend getting as thin of a glue as you can. Makes wicking in deeper easier. Also, it will spread thinner before clamping. I have found the thicker glue can make puddles between the pieces that can make them not fit tight even when clamped.

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I'm in the glue the matrix camp. Clean it well, apply glue to one side, fit and clamp. I don't worry too much about having too much glue. If you clamp it properly, you'll squeeze out any extra glue. You just gotta be prepared to deal with the mess. :P

 

I glue the matrix for the added support. If you have to prep past the glue joint, it can be a bit of a pain but I've had too many glued fossils break during prep when only the fossil had glue. There's a lot of stress introduced during prep. Your medium viscosity cyanoacrylate will work just fine.

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