Mammoth Tusk Reconstruction advice

[Chase97]

Looking for some advice on how to stabilize and piece together this mammoth tusk. It came from Iowa. It appears to have some sort of sheen on it right now but the lady I bought it from said that she knows nothing has been done to it for years and didn’t know exactly what was done to it. After doing some research I thought I would do a very diluted acetone and paraloid  B72 solution to consolidate it. After that do you think it would be possible to use a much thicker acetone and paraloid solution to join the pieces together to make it one again? Just looking for any advice and or help before I start this project. Thank you in advance!

[Randyw]

Wow! Great looking piece. On this I think we need to call in our resident restorer @Ptychodus04. matter of fact he just got done working on one!

[Ptychodus04]

Do a test on a section with some acetone and see if whatever is in the tusk comes off, or gets sticky. If it comes off, I would suggest removing it all before you consolidate. It’s probably a lacquer or shellac.

 

Normally, I would advise soaking in Paraloid to consolidate but we don’t know if there’s glue holding anything together and you don’t want that weakened by the acetone in the solution. I’d brush it on and pour some into the cracks.

 

Paraloid can be used as a glue for smaller objects but this is probably too heavy for that to be feasible.

 

The AMNH recommends Devcon 2 Ton epoxy for heavier specimens. Most of the time, epoxy is avoided but in situations like this, it’s the best option.

[Chase97]

14 hours ago, Ptychodus04 said:

Do a test on a section with some acetone and see if whatever is in the tusk comes off, or gets sticky. If it comes off, I would suggest removing it all before you consolidate. It’s probably a lacquer or shellac.

 

Normally, I would advise soaking in Paraloid to consolidate but we don’t know if there’s glue holding anything together and you don’t want that weakened by the acetone in the solution. I’d brush it on and pour some into the cracks.

 

Paraloid can be used as a glue for smaller objects but this is probably too heavy for that to be feasible.

 

The AMNH recommends Devcon 2 Ton epoxy for heavier specimens. Most of the time, epoxy is avoided but in situations like this, it’s the best option.

 

[Chase97]

@Ptychodus04 thank you for your reply and suggestions! I was hoping to get a response from you. Last question. Would you recommend B72 to consolidate it like was the original plan after wiping off the substance that’s on there now or I have been hearing that paleobond 750 is an excellent tool to consolidate as well? What’s your suggestion?

[Ptychodus04]

33 minutes ago, Chase97 said:

@Ptychodus04 thank you for your reply and suggestions! I was hoping to get a response from you. Last question. Would you recommend B72 to consolidate it like was the original plan after wiping off the substance that’s on there now or I have been hearing that paleobond 750 is an excellent tool to consolidate as well? What’s your suggestion?

 

I'm always happy to pontificate regarding proper fossil preparation. 

 

I prefer the Paraloid B72 over all other consolidation materials. I have not used the PB750 and can't find any data on its strength rating but it is marketed as a structural adhesive rather than a consolidation material. You can also mix some thick paraloid and pour it into the wider cracks in the tusk before you start to reassemble it. On specimens like this, I want as much plastic inside it as possible to lock things together.

[Chase97]

1 hour ago, Ptychodus04 said:

 

I'm always happy to pontificate regarding proper fossil preparation. 

 

I prefer the Paraloid B72 over all other consolidation materials. I have not used the PB750 and can't find any data on its strength rating but it is marketed as a structural adhesive rather than a consolidation material. You can also mix some thick paraloid and pour it into the wider cracks in the tusk before you start to reassemble it. On specimens like this, I want as much plastic inside it as possible to lock things together.

I will do just that! Just purchased some B72. Can’t wait to start the process! Thank you again for your help!

[Chase97]

Just now, Chase97 said:

I will do just that! Just purchased some B72. Can’t wait to start the process! Thank you again for your help!

@Ptychodus04

[jpc]

Do the acetone test ptych mentioned to see if it is being held together with an acetone based glue.  If it is, any addition of acetone will risk the acetone dissolving any old glue before the new Paraloid does its magic.  

[hadrosauridae]

Probably not the best fossil to make your first attempts at preparing.  You should spend a lot of time researching and reading about consolidating fossils, chemicals, glues, etc before you start.  Just to clarify a couple things posted, PB750 is a cyanoacrylate glue.  It is thick.  It is NOT for consolidation.  It is also on the "light" end of structural  repair.  You want something stronger.  PB02 is a super-thin cyanoacrylate glue that is good for consolidating micro-cracks and broken ends before repairing.  It souldnt be used as a glue except on small items that naturally have a tight fit.  If you find (or have significant doubts) that there has been past repairs, it would be wise to dissolve your paraloid in 100% alcohol instead of acetone.  Either way, it would probably be a good start to wrap each piece with lots of hose clamps, using light pressure.  Dont give it a chance to fall apart when you soak it.

 

[Chase97]

1 hour ago, hadrosauridae said:

Probably not the best fossil to make your first attempts at preparing.  You should spend a lot of time researching and reading about consolidating fossils, chemicals, glues, etc before you start.  Just to clarify a couple things posted, PB750 is a cyanoacrylate glue.  It is thick.  It is NOT for consolidation.  It is also on the "light" end of structural  repair.  You want something stronger.  PB02 is a super-thin cyanoacrylate glue that is good for consolidating micro-cracks and broken ends before repairing.  It souldnt be used as a glue except on small items that naturally have a tight fit.  If you find (or have significant doubts) that there has been past repairs, it would be wise to dissolve your paraloid in 100% alcohol instead of acetone.  Either way, it would probably be a good start to wrap each piece with lots of hose clamps, using light pressure.  Dont give it a chance to fall apart when you soak it.

 

@hadrosauridaeSo if it wipes off with acetone then it was done with acetone correct? What if it doesn’t wipe off am I ok to use acetone then?

[Ptychodus04]

10 hours ago, Chase97 said:

@hadrosauridaeSo if it wipes off with acetone then it was done with acetone correct? What if it doesn’t wipe off am I ok to use acetone then?

The acetone test is only to determine if the mystery material is subject to dissolution in acetone, it won’t tell you what the material is.

 

I would not, under any circumstances soak this specimen to consolidate it. It could be held together by something that will lose its structure as @jpc mentioned. Even using ethanol as your Paraloid solvent is not safe as some things used in the past are soluble in alcohol.

 

It’s likely your acetone test will not fully remove the mystery material. It might just temporarily soften it. If it does, repeat the same test in a different place with ethanol, and in a 3rd place with isopropyl.

 

These are the 3 most common solvents that affect old consolidation materials. Whichever one has the least effect on it is your safest solvent for your Paraloid solution.

 

[trilobites_are_awesome]

On 10/21/2024 at 12:20 AM, Ptychodus04 said:

Devcon 2 Ton epoxy

Have you ever used the devcon?

 

I have a HUGE South Dakota ammonite that is split in half and am trying to research what glue/apoxie would be best.

[Ptychodus04]

34 minutes ago, trilobites_are_awesome said:

Have you ever used the devcon?

 

I have a HUGE South Dakota ammonite that is split in half and am trying to research what glue/apoxie would be best.

 

I have not personally used it. Any 24 hour cure epoxy will take care of your ammonite and will hold up longer than quick set epoxies. I've also used the non-expanding Gorilla glue with great results but can't recommend it as it hasn't really been tested for long term curation. It is super strong and bonds well. 

[Balance]

@Ptychodus04 @jpc

 

Do y’all ever “dowel” repairs like these? 
 

If I’m mating two “butt joints” I’ll drill a hole with some manner of cardboard template. This puts the hole in the same center on both pieces. Then you could slip an aluminum or wooden dowel in both sides to give it structural stability.  
 

Same long cure epoxy along with that step. 
 

??

 

Jp

 

edit:  Forgot to mention I used Devon products exclusively for over 10 years until about 3-4 years ago. The once “clear” epoxy was starting to yellow after a very short period. Failure rate also increased. So I stopped using Devcon and went back to JBweld brand.  Since failure rate is almost non existent and it’s back to crystal clear after a year or two. 
 

I think all these products are made by the same parent company. The bottles for every single brand are the same. The instructions are the same. Cure and set times the same. So I wonder if Devcon was buying the formula from JBweld or whomever owns JBWekd and then the didn’t renew the copyright or patent??

Edited Tuesday at 03:10 PM by Balance

[trilobites_are_awesome]

1 hour ago, Ptychodus04 said:

 

I have not personally used it. Any 24 hour cure epoxy will take care of your ammonite and will hold up longer than quick set epoxies. I've also used the non-expanding Gorilla glue with great results but can't recommend it as it hasn't really been tested for long term curation. It is super strong and bonds well. 

Thanks!

[jpc]

dowels... I did this once.  It is easy on wood where you can get the dowel hole to go into the wood perfectly perpendicular to the surface being joined.  This is incredibly difficult with uneven surfaces as the dowel holes must be perfectly aligned.  I did it once on a block that was small enough that I placed the two pieces into position and was able to drill into the outside of one and drill straight into the second block, thereby creating a single hole in two blocks.  I used a piece of coat hanger as the connecting 'dowel'.  HOpe this makes sense.

[jpc]

use 2 ton or 24 hr epoxy, not 5 minute epoxy which does not stand the test of time.  

 

 

[Balance]

2 minutes ago, jpc said:

dowels... I did this once.  It is easy on wood where you can get the dowel hole to go into the wood perfectly perpendicular to the surface being joined.  This is incredibly difficult with uneven surfaces as the dowel holes must be perfectly aligned.  I did it once on a block that was small enough that I placed the two pieces into position and was able to drill into the outside of one and drill straight into the second block, thereby creating a single hole in two blocks.  I used a piece of coat hanger as the connecting 'dowel'.  HOpe this makes sense.

That makes perfect sense. 
 

I deal with this with furniture. With furniture repairs (think a turned leg of a chair with broken , jagged edges) I’ll drill the hole too big. So a 3/8” hole for a 1/4” dowel. Down in the holes  I’ll usually put a 1/4” pocket for the dowel to sink into snug but because it’s oversized I can move each section around with the dowel inserted to get them room to match up. I’ll overfill my holes with epoxy or wood glue  so once it’s dried the holes are still strengthened but I didn’t have to be dead on with each piece. Basically an epoxy dowel with a dowel inside it to give it strength at that point. 

[jpc]

25 minutes ago, Balance said:

That makes perfect sense. 
 

I deal with this with furniture. With furniture repairs (think a turned leg of a chair with broken , jagged edges) I’ll drill the hole too big. So a 3/8” hole for a 1/4” dowel. Down in the holes  I’ll usually put a 1/4” pocket for the dowel to sink into snug but because it’s oversized I can move each section around with the dowel inserted to get them room to match up. I’ll overfill my holes with epoxy or wood glue  so once it’s dried the holes are still strengthened but I didn’t have to be dead on with each piece. Basically an epoxy dowel with a dowel inside it to give it strength at that point. 

I like it.  I do some woodworking to and will keep this in mind.  

 

 

[Ptychodus04]

@Balance I have used a similar "dowel" process to the one you described above. I have also heard about a process that the Gray Fossil Site uses for spanning gaps with Paraloid. I haven't delved deeply into the process but they build a mesh of thin Paraloid strands to support pieces that don't fit well together. I guess I need to do some research.

 

I did a repair of a broken mastodon humerus where a large section of the trabecular bone had crumbled, leaving a large hollow below the harder cortical bone. I consolidated the bone with a massive amount of Paraloid on both ends, hardening it and filling the pores with plastic. Then, I drilled out a space in each end for the dowel, offset from each other and set them with Paraloid. The sections of dowel were long enough to span the gap but just short enough to miss the opposite edge of the hollow. I then packed each side with Apoxie Sculpt (slightly overfilling the sections) and shoved the sections together after smearing some Paraloid on the cortical bone. A ratchet strap was employed to hold everything tight for a week to ensure a strong bond. The resulting bond was insanely strong.