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Mosasaur skull - Broken, fragile, in need of advice...


Scribbler

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Hello TFF members - I'm in need so some advice on this one please.

 

So this is my first post (happy to be corrected on any newbie errors) and although preparation is my favourite part of the fossil game, I am 'fairly' new to it - In other words, please go easy on me, I'm aware it's going to be all too tempting to say I've bitten off more than I can chew here...  :unsure:

 

I recently purchased this Mosasaur skull from a well known European fossil auction site; you may have seen it yourself if you follow such things.  It wasn't 'hugely' expensive, but that doesn't mean I'm not serious about making something good out of it and giving it a lot of attention (which clearly it will need...).

 

It is from Morocco, was sold as a Platycarpus (from the teeth I would tend to agree, but please correct if you think otherwise) and originally was complete in a plaster jacket.  The seller decided to prep it and remove from the jacket.  Whilst this may have exposed more of it, some quite nicely, they have also turned it into the most insanely fragile fossil I have ever come into contact with!  It was already in five large pieces when advertised for sale, and despite being very well packaged, has suffered further in transit.  The matrix is not much more than hard (ish) sand and the bone only marginally more solid.  Doesn't help that it's so crushed, so only matrix between each piece.

 

Clearly leaving it in the matrix, perhaps replacing the jacket with something more aesthetically pleasing as part of a mount and prepping only the surface would have been the way to go, but it's beyond that now, so I would really love some thoughts and suggestions on the following:

 

1 - Immediate stabilisation and strengthening to prevent further breakages and reattach the broken sections (buckets of CA to solidify the sand matrix and reduce porosity to enable gluing?)

2 - Rebuilding/mounting (combining these two, as it will never be strong enough to hold in one piece and the mounting technique will likely need to be integral as it will need complete support across the entire back.  It would never be my first choice, but I'm thinking a rebuilt matrix under the fossil to support and hold it together at the same time?)

 

Ok, lots of text there for background and to give you more context, here are some pictures which will help...

 

Original, in jacket:

 

5e0bd06ce5c82_Mosasaur-Inmatrix.JPG.dbc660de702a099bae2c55ad1f217311.JPG

 

Advert pics:

 

5e0bd0942c37b_Mosasaur-All(lower).thumb.jpeg.73fde92d56c7b1f802e31585f4e42987.jpeg

 

And another:

 

5e0bd0e49732c_Mosasaur-Detail(snout).thumb.jpeg.b06b1a45f7667663f88f7e73ace78105.jpeg

 

Now it's home, in a slightly more confused state:

 

5e0bd145df320_MosasaurHome10.thumb.jpg.df6b5a90b63145f105471b14ad9b58af.jpg

 

And another:

 

5e0bd1b3854d6_MosasaurHome8.jpg.8255cc1a82b2246dedecb0e92ca0b74d.jpg

 

Last one, you get the idea:

 

5e0bd21bb532a_MosasaurHome1.jpg.f523c3fbf6708ec959f4077a2fdb284e.jpg

 

If anyone is interested in seeing more of it, please let me know, have lots of pics.  It's an interesting item and despite being crushed to hell, looks to be fairly complete (the reverse tells it's own story too, more teeth there, etc.), but it's realistically only ever going to be an 'in matrix' display piece.  Out of curiosity, I believe it's upside down, with the two maxilla visible on top and the upper jaw section being below, sure someone will easily be able to confirm?

 

Anyway, enough from me, would love your thoughts and really appreciate anyone who has the time to consider and reply.  If I haven't been clear or you need more info, please just let me know.  :)

 

Thank you,

Dave

 

 

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Welcome to TFF.
 

Consolidate the whole thing with Paraloid. I would not soak the pieces in case there are glue joints you don’t see, so brush it on. Dissolve 1 part Paraloid in 50 parts acetone. 

 

Once you have the piece consolidated, I would use a slow set epoxy or non-expanding clear Gorilla glue to put the pieces back together. For these oddly shaped pieces, you can clamp them by using a ratchet strap around them to hold the soon on the joint. Glue one joint at a time, leaving the pieces clamped for at least 2 days per joint.

 

Once this is finished, you can wipe the whole thing with a rag soaked in acetone to remove some of the sheen caused by the Paraloid if you so desire.

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If it were mine...

To start, many photos of how it goes together.

Next consolidate all visible bone with Vinac or similar material - both sides

Glue Pieces together (piece by piece) with temporary support beneath to assure alignment

Establish display side

Mount on board with form fitting support between fossil and mount surface...perhaps a "shadow box" with metal prongs to secure the piece when the entire rig is upright 

Final prep on display side... clean up...improve aesthetics

Good luck, have fun

 

Edit: That sneaky Kris beat me by a few seconds...listen to him.

Human beings, who are almost unique in having the ability to learn from the experience of others, also are remarkable for their apparent disinclination to do so. - Douglas Adams, Last Chance to See

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I’m an old fool and haven’t been prepping long but if it were mine I dont know if I could resist consolidating all visible pieces and prepping it out and reconstructing it piece by piece. It would probably take me a year or better but super glue and paraloid is cheap. It’d have to be supported from behind the pieces as I went.... but that’s just me. I’m a sucker for impossible preps.....a difficult prep and an almost impossible puzzle. What could be better? ****note***** I am not recommending this by the way just stating what I would probably stupidly try to do....

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I would go with what Kris and Snolly have suggested.  Best to put it back together then leave it alone.  If you try to take it apart you may be surprised to find that a lot of those pieces from the posterior end (jaw joint end) might not fit together.  It will look cool as it was in the first photo.  

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Thank you all, very helpful.

 

Randyw - Reconstructing it was my original 'hope', but it just isn't going to be possible.  Not only are there just too many tiny fragments (I wouldn't want it to appear like one of those reconstructions which look like hundreds of bits, which could be in any order TBH), but they are also too fragile and I fear if I went down that route, I wouldn't be left with a pile of bone fragments I couldn't rebuild, but a pile of dust!  :o  I'm struggling to add more than one photo to this reply, will show you what I mean below...

 

Kris, Snolly, JPC - Getting it back to present in its 'found' state is the direction I will go.  A couple more questions, if you don't mind...

 

Snolly - I love the idea of a shadow box mount.  However I just can't see it being strong enough to 'stand alone' no matter how stabilized and how strongly re-glued.  The joint across the centre in ridiculously tiny, probably about 5 square cm in total.  I suspect it would break every time I breathe near it (see below) and making a mount with form supports (individually) would probably have to resemble one of those pin art boxes.

 

 5e0c8119b35e5_Mosasaur-Centraljoint.thumb.jpg.73e4716d24af49f807ff6b21d1d9e0d4.jpg

 

Kris - Could you please let me know why Paraloid brushed on would be better than CA brushed/dripped on?  Does it soak in better/further?  The reversibility?  The fact it doesn't stick to every other snarge thing in the vicinity as well and harder to remove if it gets on the display side?  CA turns the sand matrix hard as cement (helpful in this case), so keen to understand more about the advantages of using Paraloid instead?  (Please don't misunderstand my question as challenging your advice, just helpful learning for me)

 

My thinking, which is a mixture of your suggestions [please shoot down as appropriate]:

 

- Stabilize (as suggested here) and re-glue as many pieces as possible, ideally back to the original five pieces or fewer

- Build a box slightly larger than fossil and fill with damp/sticky sand.  Cover with cling film to avoid damp sand/fossil coming into direct contact

- Place sections in, so they 'bed' and make a form of the entire fossil underside

- Remove carefully and use sand to make a mould of the reverse; I'm thinking it could be filled with deep-set latex floor screed (strong, flows to fill so no pushing around which could change the shape, etc.)

- Once hard, remove and use as a mould to make a mount (which should effectively be the shape of the original sand mould of the fossil reverse)

- This could be made of anything suitable and only as thick as it needs to be.  I'd probably go for GRP/fibreglass

- Mount the fossil into this 'shell', which would be hidden (doesn't need to protrude beyond the edges of the fossil).  We can discuss mounting with what adhesive later

- This can then be used in a shadow box in whatever frame/background colour/etc. is most pleasing

 

Crazy (quite possibly), genius (highly unlikely), other ideas (almost certainly)?

 

Thanks again!

Dave

 

Mosasaur - Matrix side.jpg

Mosasaur - Fragile bone close up.jpg

Mosasaur - Fragile bone close up.jpg

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Oooo, on posting I see it did throw in (several) other photos I'd been trying to upload... 

 

Randyw - You see my crumbly bone issue (twice in fact)  :DOH:

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1 hour ago, Scribbler said:

Snolly - I love the idea of a shadow box mount.  However I just can't see it being strong enough to 'stand alone'

Hello, my inchoate, brainstorm approach was to "back" the piece with some material (e. g. clay, putty) that would serve to embrace the non-display side and provide a flat surface to interface the rear of the shadowbox. This would provide stability back to front for the glued fossil. However, seeing the small surface area available to rejoin some of the pieces; this seems impractical, as it probably would not withstand gravity when displayed on edge. I also thought of a fiberglass backing. This applied directly to the non-display side would be plenty beefy enough. However, applying the liquid resin to the irregular back without contaminating the display side - tricky. In the linked example I simply used a tape dam on the even edges of the plate - pretty easy; but not so practical for your irregular shape and contour. Perhaps a carefully applied removable clay dam to encircle the reverse during application? That should contain the resin until it cures. If you could pull off the application of fiberglass, it would allow the strengthened fossil to "float" in the shadowbox with no apparent reinforcement evident. It would look spectacular! (I think). This approach seems a bit more direct at the problem, as opposed to your ambitious idea outlined above (which if not "genius," at least ingenious.)  

Good luck, have fun, it's a stellar project to have.

 

Edit: An additional thought, with the direct fiberglass backing approach; you could lay in a number of bolts during application. These could then be utilized to attach the piece to the wooden shadowbox back wall. The bolts might be most stable, if they protruded from a thin piece of sheet metal that ran a good length of the fossil's back. The whole rig, metal strip and bolts would become encased in the fiberglass.

 

 

 

Human beings, who are almost unique in having the ability to learn from the experience of others, also are remarkable for their apparent disinclination to do so. - Douglas Adams, Last Chance to See

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Thanks Snolly, lots of great thinking here.  However it is done, your method or mine (or a combination), this is a strong, lightweight and cheap option.  All winning points in my book (and thanks for link BTW, read with interest).

 

The metal strip with bolts/threaded bar is a great idea.  Can be adjusted and cut to length to have the perfect 'floating' effect in a shadow box.

 

I'm going to focus on getting it stabilised and re-glued as much as possible and then try out some ideas for support - I'll be back, as a great philosopher once said...  Seems a few are interested to see how I get on so I'll keep you updated with pics as I go.

 

First things first, if I'm to avoid a divorce during the prep, I need to be able to get it off the kitchen table (where I tend to do most 'non dusty' prep work) and out the way of kids without risk of causing further damage every time, so a stretcher was knocked up today!  :default_clap2:

 

5e0cd9c103df1_Mosasaur-Stretcher.jpg.83577486b19c06b0803319d6b66985c9.jpg

 

 

 

 

Mosasaur - Stretcher 2.jpg

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Hey @Scribbler this is quite a project. Paraloid is preferable to cyanoacrylate in many ways. It will typically soak in better, it is easily reversible, and it is cheaper in the long run for a large project such as this. Also, Paraloid is a simple plastic rather than a glue. It does not degrade or cross-link over time as glues can.

 

You can build up the thinner areas and support the back side with Apoxie Sculpt. It comes in many colors and it is applied like modeling clay. It is a permanent application so you better mean it when you put it on. I’ve used it to support delicate fossils many times.

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Thanks Kris, that's clear and helpful.  I'll get myself some Paraloid and Acetone.

 

I do like that idea of directly supporting/strengthening the back of the individual pieces with a product like this.  It would be similar to the GRP idea discussed with Snolly, but easier and more precise to apply.  Given my experience of GRP, it tends to get in/on places you don't want it and is a b*gger to get off anything it touches.

 

Apoxie Sculpt isn't so easy to get hold of in the UK (at least it's very expensive), but I'm assuming any similar product would do the trick?  They all go rock hard and are permanent.  Many of these sorts of products are very similar and get used for different applications (with prices varying according to the budget/volume of said application/user).

 

I was thinking of using chemical/anchor resin, the sort that comes in tubes with a gun and used in construction.  Various types are available; polyester, epoxy, vinylester, but all set like granite and are fairly clean and simple to apply from a tube.  Any reason you can think of why this wouldn't work or should be avoided?

 

Once the (five) pieces are back together and strong, whatever chosen mounting technique will have a considerably reduced risk of causing damage.

 

 

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2 hours ago, Scribbler said:

Apoxie Sculpt isn't so easy to get hold of in the UK (at least it's very expensive), but I'm assuming any similar product would do the trick?  They all go rock hard and are permanent.  Many of these sorts of products are very similar and get used for different applications (with prices varying according to the budget/volume of said application/user).

 

I was thinking of using chemical/anchor resin, the sort that comes in tubes with a gun and used in construction.  Various types are available; polyester, epoxy, vinylester, but all set like granite and are fairly clean and simple to apply from a tube.  Any reason you can think of why this wouldn't work or should be avoided?

Any of the slow setting epoxy clays would be fine for this application. I have used Magic Sculpt in the past as well. My only concern with using an adhesive that is dispensed from a tube is the viscosity of the adhesive. They tend to have a caulk-like consistency and the higher viscosity might cause the adhesive not to fill in some gaps. You would just have to be more intentional about spreading it around I would think. The other concern is lifespan of the adhesive. Those are unknown in the construction adhesives. Adhesives that quickly cross-link will experience shrinkage that may be acceptable in the construction industry but would be catastrophic to your fossil. It's a bit of a dice roll.

 

Amy Davidson (AMNH) recommends Devcon 2 ton slow set epoxy for high strength bonds for heavy specimens (i.e. saurapod bones).

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Thanks Kris.  I did some research and you are absolutely right.  Of these three product types I listed, epoxy resin is the best (strongest with no shrinkage), then vinylester (nearly as good) and lastly polyester resin (strong, but not as long lasting and prone to shrinking over time).

 

I think I'll just play it safe and splash out the extra cash to find some of your Apoxie Sculpt - It's not crazy (about $100 in your money for a 4lb tub).  Looking at the pictures and your text, I assume it has the consistency/viscosity of a thick liquid/silicone sealer, rather than a clay/caulk, meaning it can be with a spatula, rather than pushed on with a trowel? 

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1 hour ago, Scribbler said:

Thanks Kris.  I did some research and you are absolutely right.  Of these three product types I listed, epoxy resin is the best (strongest with no shrinkage), then vinylester (nearly as good) and lastly polyester resin (strong, but not as long lasting and prone to shrinking over time).

 

I think I'll just play it safe and splash out the extra cash to find some of your Apoxie Sculpt - It's not crazy (about $100 in your money for a 4lb tub).  Looking at the pictures and your text, I assume it has the consistency/viscosity of a thick liquid/silicone sealer, rather than a clay/caulk, meaning it can be with a spatula, rather than pushed on with a trowel? 

Apoxie Sculpt has a clay consistency. You would apply it by hand the same as modeling clay. You do not want to use it as your bonding agent, only as the support for the back/thin areas. For the bond, you would want to use the lower viscosity slow set epoxy like the Devcon.

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I little progress update and a question...  I've been taking full advantage of my enthusiasm for this project and spending too many nights into the early hours.  Time flies!

 

The method which is working best is to stabilise/strengthen the fragments, cracks, weak areas and edges (basically just sand) with CA and then rebuild either using CA (small pieces and frags) or epoxy (large sections).

 

There were around 30 small pieces which took quite some time to find where they went.  I'm happy with about 25 of them and have rebuilt, the remaining 5 proving more tricky, but I'll get there.

 

The front section of the skull is coming together nicely, see below, and after the above process it's a little stronger than I initially expected:

 

5e1241d7b3e4c_Mosasaur-Progress2.jpg.8379f95f82398ebc0117a716b1d96aed.jpg

 

So here's my question.  Given the entire skull is in exactly the position found and extracted, would it be heathen of me to reposition a tooth?  There is a beautiful tooth on the rear of the matrix (several in fact) due to the inverted position and the very front tooth in the upper jaw is missing.  Unthinkable to remove this tooth and reposition?

 

The tooth could be removed fairly easily and any tooth on the rear is going to be lost forever once I epoxy/fibreglass the back for mounting, so this would retain the tooth visibly and add something to the display effect.

 

Pics added of the tooth and the front of the nose.

 

If it's a crime even considering this, I know you won't be shy in telling me...  :whistle:

 

Thanks,

Dave

 

Mosasaur - Progress 3.jpg

Mosasaur - Progress 1.jpg

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Just to add, the entire fossil will get coated in Paraloid once back together, I'm not ignoring your helpful advice, Kris.

 

The surface has Paraloid on now and whilst it has certainly strengthened it, CA does making the edges where gluing needs to take place much stronger.

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If the tooth is from the opposite side of the same jaw element (maxila or dentary) the curvature will probably be wrong as Most teeth have a slight curve labially. If it is from the opposite member, the curve will be correct.

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Kris - Tooth is actually from the same maxila, just a little further back (would effectively be replacing tooth 1 with tooth 7 or 8),

 

I would never ‘hide’ that I’d done this (not that I’m planning on selling or parting with it anyway), just wondering it you would consider this an acceptable part of a restoration project?

 

RuMert - Nah, that’s not going to be possible, too fragile and too many bits.  Will be displayed in 2D, as found.

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5 hours ago, Scribbler said:

Kris - Tooth is actually from the same maxila, just a little further back (would effectively be replacing tooth 1 with tooth 7 or 8),

 

I would never ‘hide’ that I’d done this (not that I’m planning on selling or parting with it anyway), just wondering it you would consider this an acceptable part of a restoration project?

 

RuMert - Nah, that’s not going to be possible, too fragile and too many bits.  Will be displayed in 2D, as found.

 

Relocating the tooth is acceptable IMHO on a restoration. I have been asked to composite crowns with roots and completely fabricate missing teeth for restorations in the past. That is an acceptable practice in the industry as long as the restoration is discernible and recorded.

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Thank you, appreciate your opinion on this.  Still undecided if I will, but wouldn't waste another minute considering it, if the consensus was that this is an awful idea.

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On 1/1/2020 at 6:10 AM, Scribbler said:

Randyw - You see my crumbly bone issue (twice in fact)  :DOH:

Yep. I see your problem. 2d is the way to go on this one....

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  • 2 weeks later...

Quick update on my little Mosasaur project (do tell me to calm down if boring you).

 

The pieces have all been reattached.  Managed to get it into two large sections, which to be honest, is better than expected considering the original condition.  Cracks need a little work to gently fill/cover with original matrix material (of which I have a bag), but otherwise it's gone together nicely and is also now reasonably strong.

 

There were probably about 30 small to tiny pieces which had broken off in transit, of which I've managed to locate and reattach 28.  there are two very small pieces which I've given up on, but to be honest, a fair bit of base matrix also broke off and they could have been attached to that, so I'll never find where they went.  I need to move on, you're a long time dead...

 

I successfully removed three nice teeth from the reverse of the fossil.  Two have been relocated, one doesn't quite fit (shape, curvature) so I'll leave it and give it to my daughter for her mini display.  One in the mid jaw has worked very well (IMHO) but I'm not overly happy with the one at the very front.  I'll leave it for now, but might have to take another crack at this (or junk it) if it irritates me too much.

 

I contacted a local epoxy company to get their advice on best product for coating the reverse in to strengthen for mounting and the seriously kind chaps are making me a bespoke product which will be slow setting and exactly the consistency requested.  Making products for filling gaps in garage floors can't be that exciting and the owner was very excited to make a bespoke product for this.  Think he saw himself as the next Dr Alan Grant! :)

 

Next step will be coating the back of these two pieces (with said above epoxy mix) and then working on a GRP form to hold it all together.

 

 

 

 

Mosasaur - Progress 4.jpg

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