Oreodont Skull Turning Green?!

[ajgus]

Hi! I was recently given a partial oreodont skull to prep & restore. The reconstruction went well, there was a very little excess rock to clean away & the pieces that I do have went together smoothly. BUT after it was assembled, certain areas of the skull began turning green. The skull fragments had been stored in a temperature & humidity controlled environment  for a number of years before i began working on it. I'm wondering if a change in environments or being handled for the first time in a long time might have something to do with it? Has anyone experienced anything like this before? Much appreciated!!

[Brett Breakin' Rocks]

7 minutes ago, ajgus said:

Has anyone experienced anything like this before? Much appreciated!!

Woah .. that's crazy. I'm assuming you didn't use and water or wire brushes to clean and restore it ? It looks like copper staining of some sort .. .maybe a chemical reaction. The preppers on the site may have come across something like this. Let's wait and hear what they say. 

 

Cheers,

Brett 

[rfarrar]

I have seen green discoloration of White River fossils under 2 different situations. When bone has been exposed to a cyanoacrylate accelerator the bone often gets a green discoloration. This can happen almost immediately, or it can take long time (days or weeks) to appear. The other situation where I have seen the green discoloration is when the bone has been stored in contact with soft foam rubber packing material over a period of time.

 

Bob

[ajgus]

10 minutes ago, rfarrar said:

I have seen green discoloration of White River fossils under 2 different situations. When bone has been exposed to a cyanoacrylate accelerator the bone often gets a green discoloration. This can happen almost immediately, or it can take long time (days or weeks) to appear. The other situation where I have seen the green discoloration is when the bone has been stored in contact with soft foam rubber packing material over a period of time.

 

Bob

Ah, yes. I did indeed use a Paleobond activator spray. Is there anything that can be done to reverse these effects? And more broadly, would you recommend not using it in the future? I'm wondering why it is even used at all if it can have such effects?

Edited October 23, 2020 by ajgus
typo

[jnoun11]

hi ajgus

a fabric with acetone will removing the green due to cyanocrylate accelerator.

[Bobby Rico]

I never seen this happen before any restoration you think would have cured. It must be reacting to something in it’s environment, if you clean it off it may just come back if you can’t find the problem. Lets ask our good  friend Kris he many be able to help you@Ptychodus04. 
 

7 hours ago, rfarrar said:

bone has been stored in contact with soft foam rubber packing material over a period of time.

 

I seen packing beans  react (leak, shrink and harden ) to the the minerals in fossil . I must remember this when we get the question how to pack fossils. 
 

cheers Bobby 

[LordTrilobite]

I've seen this on several skulls before on our favourite auction site. I was wondering why they were green.

[Ptychodus04]

Thanks for the tag @Bobby Rico. @ajgus the comments above are correct regarding the accelerator. It reacts with clays in the matrix. This is why some turn green whilst others do not. The only way I have found to remove this is with bleach. Dilute (I like 1:1 to help with the smell) with water (I know you’re never supposed to put water on a dry vertebrate fossil but it is what it is here) and wipe the solution on with a rag dampened with the bleach water. Don’t use more than you have to.

[LabRatKing]

Is this a result of the benzene in the accelerator bringing dissolved copper out of the matrix?

[rfarrar]

Bleach does help, but does not entirely clear up the green. Some fossils are more susceptible to discoloration than others, and certain formulations of accelerator cause worse reactions than others. The pump accelerators tend to be somewhat less reactive than the aerosols. It is best to keep the accelerator off the exterior of the fossil just to be safe. The brush-on accelerators tend to be less reactive and easier to control than either the aerosol or pump varieties.

 

Bob

[jpc]

Others beat me to it.  Accelerant.  I do not allow this stuff in our lab.  We tried to remove some with bleach, as mentioned above, it worked or it didn't, so I just banned the stuff.  Not allowed.  

[FossilDAWG]

Out of curiosity, what is an "accelerator" in this context?  I assume we are not talking about some red shift due to accelerating the fossils to near light speed in a particle accelerator, or stepping on a gas pedal, or anything like that.  The skull in question seems quite immobile.

 

Don

[Randyw]

3 minutes ago, FossilDAWG said:

Out of curiosity, what is an "accelerator" in this context

It’s a spray that makes the super glue set up instantly. I won’t use it on my fossils... 

[FossilDAWG]

Seems dangerous, even apart from the color change issue.  I find it all too easy as it is to glue things in the wrong place, or to glue my fingers to the fossil, without making it set instantaneously.

 

Don

[rfarrar]

There are applications where the accelerator or activator is very helpful. Some types of material will not bond with cyanoacrylates without out the use of an activator. Other times where the area to be glued is very hard to keep in place the accelerator can be helpful. Also it is good when the substrate is porous and the glue must be set quickly, before it runs away into the rock. Our joke is that when instant setting glue isn't fast enough we use the accelerator...

 

Bob

[ajgus]

Wow, thank you for all of the insight. I may try some of the remedies listed above, or maybe just leave well enough alone. I'm thinking I may leave the accelerator out of the equation in the future.

[jpc]

1 hour ago, ajgus said:

Wow, thank you for all of the insight. I may try some of the remedies listed above, or maybe just leave well enough alone. I'm thinking I may leave the accelerator out of the equation in the future.

Bob makes a valid point, but it is particularly greening on White River fossils.

[smokeriderdon]

I use accelerator all the time in model building. I use the same stuff with my fossils. Never had an issue, though I have also never had a White River fossil. I also never spray it on fossils, only apply it directly to the area I need it. But good to know about this. 

On 10/23/2020 at 12:34 PM, FossilDAWG said:

Seems dangerous, even apart from the color change issue.  I find it all too easy as it is to glue things in the wrong place, or to glue my fingers to the fossil, without making it set instantaneously.

 

Don

 

I use a longer setting super glue. Its great so that I have time to move pieces around. But that can be a definite issue sometimes and I need it to bond quickly. And I use tweezers when I can to avoid the glued on fingers. LOL

[ajgus]

Thanks for all of the input. I ended up using a diluted bleach solution & it worked remarkably well. Here is a shot of the final result, complete with a modest mount that I built for it. Thanks again!