Preserving Fossils

[MSirmon]

After reading through this I have tried Butvar-76 and actually like the process. I haven’t figured out the thickness yet through as my fossils look wet but are shiny. If I read correctly that means I am too thick. Is there a way to remove and reapply or remove the glossy look?

[Harry Pristis]

 

Sure, you can flush a shiny fossil with acetone to reduce the gloss.  Or, you can wet an old toothbrush with acetone and gently scrub.  My experience is that the Butvar B-76 solution gives best results when it approaches the point of too-thin.  The fossil surface should appear damp, but without a gloss.

 

 

[DLB]

31 minutes ago, MSirmon said:

After reading through this I have tried Butvar-76 and actually like the process. I haven’t figured out the thickness yet through as my fossils look wet but are shiny. If I read correctly that means I am too thick. Is there a way to remove and reapply or remove the glossy look?

acetone with a Q tip

[Sjfriend]

What prep would be recommended on a large plate of plant fossils (mostly Meta Sequoia on this particular one) that was found along ocean high tide line? So, will have had major salt water exposure on rock. Fossils themselves were not exposed (we split rock) to water. Very solid matrix. But some of the rocks from this local do start splitting once really dry. Have used white glue mix on a couple to prevent flaking with ok results. Looking into using Vinac since it's a more professional product (looking at loaning / gifting to university).

[Ptychodus04]

9 hours ago, Sjfriend said:

What prep would be recommended on a large plate of plant fossils (mostly Meta Sequoia on this particular one) that was found along ocean high tide line? So, will have had major salt water exposure on rock. Fossils themselves were not exposed (we split rock) to water. Very solid matrix. But some of the rocks from this local do start splitting once really dry. Have used white glue mix on a couple to prevent flaking with ok results. Looking into using Vinac since it's a more professional product (looking at loaning / gifting to university).

 

I would suggest soaking in clean water with several exchanges for several days. Then, wrap the slab in towels and get them wet. Put the whole thing in a box if you have one big enough and close the top. Let it sit like this for several weeks. This will allow the fossil to dry slowly and help prevent severe cracking.

 

Then mix paraloid or butvar (Vinac is hard to find these days) with acetone (1 part plastic to 50 parts acetone) and apply several coats to the slab on all sides..

[Harry Pristis]

I agree with Kris that the slab should be de-salted.  "Very solid matrix" may require air-drying to some degree before a freshwater soak in order that the water penetrates to the salt locked into the deeper matrix.  This violates the "Never water-wet a dried fossil" but, Oh well!

 

I cannot find any value in the slow-drying regimen that Kris recommends.  I think you'd wind up with a mildew-stained towel with little advantage to the slab.  After de-salting, I would expose the fossiliferous surface to air circulation to quick-dry that face.  When that surface is dry to a fair depth (your call), I would generously apply the consolidant to that face only, minimizing the drips along the still-damp edges.  After the consolidant is dry, I might invert the slab and dry it thoroughly (for a considerably longer time) in the same manner.  Soak, slosh, or slather the dried second side with consolidant as seems appropriate.

 

Keep in mind that this advice - all of it in the thread - is based on minimum information on the nature of the material you're working with.  Extract ideas, not formulae, that you think might work best with YOUR fossils.

[Ptychodus04]

5 minutes ago, Harry Pristis said:

I cannot find any value in the slow-drying regimen that Kris recommends.

I recommended the slow drying method based on the poster's comment that the slabs from this site crack when drying. I interpreted this as caused by differential expansion due to rapid drying. If that's not the case, I would definitely not use the slow drying method (unless one likes mildew).

 

 

[Sjfriend]

My 2nd biggest concern, is what would a long soak do to leaf prints? Don't want them fading/peeling off. I understand the thought of removing the salt but what might happen if I have to prep anyway? Wish I had a hydrometer to test the rocks. Most of the rock seems very dry.

[Harry Pristis]

49 minutes ago, Sjfriend said:

My 2nd biggest concern, is what would a long soak do to leaf prints? Don't want them fading/peeling off. I understand the thought of removing the salt but what might happen if I have to prep anyway? Wish I had a hydrometer to test the rocks. Most of the rock seems very dry.

 

Only experimentation will answer your questions.

 

If the leafy surface is completely dry, you might experiment by coating that surface with consolidant BEFORE you de-salt.  You're gambling that the strength of the consolidant will overwhelm or defeat the tendency of salt to crystalize in the surface layer.  It's an experiment, after all.

 

 

[BobWill]

I see where you can get Butvar B-98 on Amazon now. Is it very different from the B-76 everyone talks about here? I didn't get any search results for it here. One website had this comment from a user who tried both.

"I ordered both the 76 and the 98, in order to see which of the 2 would work better when mixed with acetone.I use it to secure fossils in situ prior to extraction.
I much prefer the 98-- the 76 takes longer to dissolve, and does not secure as well as the 98."

[Bonehunter]

On 11/11/2008 at 9:39 PM, Harry Pristis said:

(Ahem!) I understand the reluctance to mess with the consolidant, but it is mis-guided.

If you value a vertebrate fossil (I exclude shark teeth here) -- and you want it to last -- consolidate it with a plastic.

You cannot reliably judge by eye what will happen to the bone after 2 years, or 5 years, or 15 years in your drawer. Bones with which you could drive nails when first collected may split after years in your drawer. Teeth, when thoroughly dry, may split. These splits cannot be repaired to the original condition because of distortion to the bone or dentin or cementum.

This may happen to any bone, so, if you're going to keep the bone, play the probabilities. Consolidate! Impregnation with plastic will prevent many later headaches (I'm not telling you to soak your head in consolidant). I am saying that there is nothing more disheartening to open a drawer and to find a prize specimen tooth split in two.

Trust the decades of museum experience.

Good point!. I have a number of bones, mostly bison, that have some splits already, but could still benefit I think- what is the best you recommend? I seem to remember using shellac when I was a kid, or varnish-would those work?- seems shelllac gets sticky in hotter temps?,..  Thanks!  Bone

[caldigger]

24 minutes ago, Bonehunter said:

Good point!. I have a number of bones, mostly bison, that have some splits already, but could still benefit I think- what is the best you recommend? I seem to remember using shellac when I was a kid, or varnish-would those work?- seems shelllac gets sticky in hotter temps?,..  Thanks!  Bone

Keep in mind many varnishes may yellow with age.  

[Bonehunter]

4 minutes ago, caldigger said:

Keep in mind many varnishes may yellow with age.  

So Butvar 76 seems the most commonly recommended? Thanks!   Bone

[keich1]

Help in repairing Keichousaurus-

I hope I'm sending this to the correct thread.  I've read through the discussion but I need advice to my specific case.  I've owned a sweet Keich that came from China via Germany in the mid-20th century.  In our last move, it was broken. The photos attached show the main break point with missing vertebrae. The next photo shows the cross-section, just for the sake of proving authenticity (you can see how the matrix striae curve around the bone as well as the details of the spine in cross-section). As I was lucky enough to find the missing vertebrae I placed the pieces together in the next photo and held the pieces in place in the final photo to show how it should look when finally repaired.  My question:  What adhesive should I use to repair the matrix and is there something different I should use to glue the delicate piece with the vertebrae into place?  Many thanks to all for any experience/advice.

 

[Josesaurus rex]

Is it necessary to apply the chemical compounds that you have mentioned here in all kinds of fossils?  or is it optional?  
I have teeth of megalodon,

one of carcharodontosaurus,

one of spinosaurus,

pyritized ammonites,

pieces of wood and plate with fossil leaves as the most important of my collection.  

 

Should I submit them to a specific conservation process or may they remain as they are?

[pachy-pleuro-whatnot-odon]

Very informative thread, a lot of useful insights shared here! I remember having used a 1:5 mixture of Velpon in aceton as a kid, but haven't really used any consolidant since taking up my hobby again a few years ago. I'm planning to use Paraloid B72 on a recent find in a couple of days, though, albeit primarily with the aim of making the fossil - an ophthalmosaurid vertebra - stand out from its enclosing matrix.

 

If this works out well, I have a batch of Eocene terrestrial/lacustrine fossils (primarily teeth and scutes) that I'm thinking of consolidating with Paraloid B72 as well... However, one of the things I did not find an answer to in this thread is how this would work with drying. For larger fossils I can imagine application of the consolidant with a turkey baster/ pippet or brush, but these fossils are max. 1.5 cm, thus thought impregnation / submersion in the consolidant would be the best way to go. But how would one prevent the fossil from sticking to the tweezers used to remove the fossils from the consolidant, and how would you prevent the fossils from sticking to the surface of whatever you're using to dry them on?

 

Any suggestions on this, @Harry Pristis, or am I just seeing problems that aren't there?

[Harry Pristis]

9 hours ago, pachy-pleuro-whatnot-odon said:

But how would one prevent the fossil from sticking to the tweezers used to remove the fossils from the consolidant, and how would you prevent the fossils from sticking to the surface of whatever you're using to dry them on?

 

Any suggestions on this, @Harry Pristis, or am I just seeing problems that aren't there?

 

Yes, such a problem is not there if you are using a thin, watery solution of consolidant.  Your forceps over much time may develop a coating of consolidant, but that has never been a problem.  It is not sticky.  The build-up is inhibited by frequent immersion in the consolidant.  Recycle the built up consolidant by scraping it off the forceps.  

[pachy-pleuro-whatnot-odon]

21 minutes ago, Harry Pristis said:

 

Yes, such a problem is not there if you are using a thin, watery solution of consolidant.  Your forceps over much time may develop a coating of consolidant, but that has never been a problem.  It is not sticky.  The build-up is inhibited by frequent immersion in the consolidant.  Recycle the built up consolidant by scraping it off the forceps.  

Thanks! Good to know

[Meganeura]

@Harry Pristis Reviving this thread to ask you a question - if I've put an elmer's glue/water mix on a fossil, and want to use Butvar/Vinac/Paraloid B72 or whatever on the same fossil - can I just dip it as I would any other fossil that hasn't had glue used on it?

[pachy-pleuro-whatnot-odon]

34 minutes ago, Meganeura said:

@Harry Pristis Reviving this thread to ask you a question - if I've put an elmer's glue/water mix on a fossil, and want to use Butvar/Vinac/Paraloid B72 or whatever on the same fossil - can I just dip it as I would any other fossil that hasn't had glue used on it?

 

I've noticed that if completely immersed my waterproof wood glue will come undone from the acetone. And as this is normally the case for water-based glues immersed in water as well, I'd expect the same to happen to these glues in acetone. A thin white film may, however form, that you'll need to clean either with acetone or a preparation needle. You'll then need to redo your old restorations. However, if you just use application, the acetone may evaporate before affecting the glue and you'd be okay. Also, don't forget that thick enough Paraloid will act as a glue to, a trick I've used many times when a small piece of a fossil broke off during impregnation: just put it back in place while the Paraloid is still wet, maybe apply an additional layer on top, and everything's back to the way it was...

[Meganeura]

2 minutes ago, pachy-pleuro-whatnot-odon said:

 

I've noticed that if completely immersed my waterproof wood glue will come undone from the acetone. And as this is normally the case for water-based glues immersed in water as well, I'd expect the same to happen to these glues in acetone. A thin white film may, however form, that you'll need to clean either with acetone or a preparation needle. You'll then need to redo your old restorations. However, if you just use application, the acetone may evaporate before affecting the glue and you'd be okay. Also, don't forget that thick enough Paraloid will act as a glue to, a trick I've used many times when a small piece of a fossil broke off during impregnation: just put it back in place while the Paraloid is still wet, maybe apply an additional layer on top, and everything's back to the way it was...

It’s Elmer’s glue that I used actually - but that’s good to know! I’ve got my whale vert that I put one coat of Elmer’s glue/water on that I want to dip. Or paint. 

[Harry Pristis]

5 hours ago, Meganeura said:

@Harry Pristis Reviving this thread to ask you a question - if I've put an elmer's glue/water mix on a fossil, and want to use Butvar/Vinac/Paraloid B72 or whatever on the same fossil - can I just dip it as I would any other fossil that hasn't had glue used on it?

I think you're stuck with the white glue.  

The acetone will break down the white glue joins and coating (I say coating because the white glue does not penetrate very well).  You will be left with strings of adherent snot which will resist removal.  Better to live with the original coating.

  White glue has very limited use as a consolidant.  I think I have never felt the need to use white glue to consolidate a Florida river fossil.

 

Here's what 'oilshale' had to say about white glue (wood glue is just another polymer formulation):

"Don't get me wrong - Elmer's White glue is a great stuff for glueing wood and can be also great for "hardening" crumbly fossils!

"But I fully agree with Harry's opinion (even so I am a polymer chemist and my job is to develop white glues and other latices....): I would never use a white glue unless the fossil is wet, crumbly and the substrate is porous and can't be dried before consilidation!

"There is no way to remove this white glue once dried (not even with solvent). It will form a dense polymer layer on the surface without penetrating much into the substrate (white glue are tiny polymer particles dispersed in water with a particle size of around 1µm, so the penetration depth won't be much).

"Butvar, a Polyvinyl butyrate (the company I am working in is also producing these polymers, of course different brand names) in this respect is much better (will penetrate better and can easily be removed by solvents).

"I do have a couple of fossil fish which were mistreated by someone else in such a way. Since the substrate was almost nonporous (diatomaceous earth!) and quite soft (and may be also the amount of white glue and concentration used was too high) there is now a thick slightly yellowish polymer film on top. Unfortunately, this is not all: The film shrinks and now peels off (with bones attached to the polymer film of course)!
Thomas"

[Meganeura]

4 minutes ago, Harry Pristis said:

I think you're stuck with the white glue.  

The acetone will break down the white glue joins and coating (I say coating because the white glue does not penetrate very well).  You will be left with strings of adherent snot which will resist removal.  Better to live with the original coating.

  White glue has very limited use as a consolidant.  I think I have never felt the need to use white glue to consolidate a Florida river fossil.

 

Here's what 'oilshale' had to say about white glue (wood glue is just another polymer formulation):

"Don't get me wrong - Elmer's White glue is a great stuff for glueing wood and can be also great for "hardening" crumbly fossils!

"But I fully agree with Harry's opinion (even so I am a polymer chemist and my job is to develop white glues and other latices....): I would never use a white glue unless the fossil is wet, crumbly and the substrate is porous and can't be dried before consilidation!

"There is no way to remove this white glue once dried (not even with solvent). It will form a dense polymer layer on the surface without penetrating much into the substrate (white glue are tiny polymer particles dispersed in water with a particle size of around 1µm, so the penetration depth won't be much).

"Butvar, a Polyvinyl butyrate (the company I am working in is also producing these polymers, of course different brand names) in this respect is much better (will penetrate better and can easily be removed by solvents).

"I do have a couple of fossil fish which were mistreated by someone else in such a way. Since the substrate was almost nonporous (diatomaceous earth!) and quite soft (and may be also the amount of white glue and concentration used was too high) there is now a thick slightly yellowish polymer film on top. Unfortunately, this is not all: The film shrinks and now peels off (with bones attached to the polymer film of course)!
Thomas"

I appreciate the response! I only used it on the whale vert I have, which was found in Bone Valley - and I really didn't want it to break.  It was crumbling a good bit before I put the glue on it. Didn't know about plastics for preservation before that, unfortunately. I'll make sure I preserve the whale tooth I have with plastic though. 

Edited July 12, 2022 by Meganeura

[Fin Lover]

Should I put Paraloid on all of this tooth, or just where there is no enamel (root, bourlette and peeled area)?  If I put it on all of it, would I use the same strength for all of it, or would I use a weaker solution on the enamel?  From reading posts, I think many people don't put it on the enamel, but I don't want more to peel.  Thank you!

[hadrosauridae]

1 hour ago, Fin Lover said:

Should I put Paraloid on all of this tooth, or just where there is no enamel (root, bourlette and peeled area)?  If I put it on all of it, would I use the same strength for all of it, or would I use a weaker solution on the enamel?  From reading posts, I think many people don't put it on the enamel, but I don't want more to peel.  Thank you!

 

I would submerge it in a 2% solution for a minute, then take it out to let it dry.  Give it a day to thoroughly dry.  The surface may appear dry, but because it soaked in, it can take a while to completely evaporate all acetone.  Any excess consolidate on the surface can be removed with air abrasion or with a cotton ball dipped in acetone.