Do I Need To "treat" Or "prep" My River Bones?

[JpaIowa]

Here is my scenerio and question: I'm finding bones and teeth in a river, some are fossilized, others arent. Most of them are pretty solid and free of cracks. I bring them home and have been storing them in clean water (it seems this would be the thing to do for now since they have been in water for a long time). My question is, before letting them air dry do I need to do anything to them to keep them from cracking or becoming less stable? Ive got some nice pieces and would hate to have their condition go south. Any advice would be greatly appreciated. Thanks.

[Xiphactinus]

JpaIowa -

Here's how I've treated bones from a river....

I get some Vinac, here's a source: http://www.bhigr.com/store/product.php?productid=262&cat=37&page=1

and mix up a dilute batch.

Let your bones dry slowly (inside or in a garage, not out in the sun).

When they are really good and dry (and they might be fragile at this point) really soak them in vinac. It will consolidate them and make them strong. That should do it.

[Harry Pristis]

There is a good chance that some of your bones and teeth WILL go south, if you don't consolidate them.

[From an earlier thread]

"Here is a workable technique for consolidating fossils.

Polyurethane will not give the desired penetration of the fossil. This resin is very difficult to remove. Putting polyurethane on a fossil is usually a bad idea.

I recommend against white glue (polyvinyl acetate) as a consolidant because there are better materials available.* (Normal prep lab dilution of white glue is one part water to two parts glue.) Rarely, a specimen cannot be dried without it crumbling, and white glue is the only reasonable answer. In my experience, white glue is messy and never looks good when the specimen is fully-prepared.

A much better material for bone is a polyvinyl butyral plastic such as Butvar B-76, but that material may be hard to find in small quantities. I have used this plastic, dissolved in acetone, for many types of fossils. (I have used it successfully on Silurian-age shales with brachiopods, for example.) It penetrates well, and in the proper dilution it produces a "damp-looking" finish with no gloss.

Butvar B-76 (but not other Butvar varieties) is also soluble in alcohol. (I assume that is denatured alcohol that you can buy in gallon cans.) I have never tried this solution for consolidation. The alcohol takes considerably longer to boil off the treated specimen.

So, what works best? [most convenient, if you don't have Butvar-76] I recommend a solution of Duco Cement (clear, like model airplane glue) in acetone.

Dilution? Start with a tube of glue dissolved in about five or six ounces of acetone in a glass jar with a metal screw-top. Shake well.

Adjust the dilution with more acetone until, after shaking, the tiniest air bubbles are just slightly retarded in their rise to the surface.

I usually heat specimens with an infra-red lamp to drive off moisture just before dipping the fossil. I do this with all sorts of fossils, and have never had one damaged by the heating. The untreated specimen is always at least as wet at the relative humidity of the air around it, I suppose. (A microwave oven may be as effective, but I've only dried glass beads for my air-abrasive unit.)

Do NOT heat the acetone solution directly. The acetone solution will get warm after dipping a number of heated fossils. You must have good ventilation to deal with the fumes!

I use a long-jawed forceps -- ten-inch tweezers, really -- to dip and/or retreive the fossils from the jar.

Ideally, you would submerge the dry specimen in this consolidant for a brief time (say 15-30 seconds, or until the specimen stops fizzing). Set each wet specimen aside to dry on cardboard (I use beer-flat because that cardboard is absorbant and doesn't readily stick to the fossil).

To avoid pooling of consolidant which may want to drain from a bone, I rotate the bone once or twice in the first minute or two after placing it on the cardboard. This helps avoid a "drip-bead" of consolidant near the lowest point of the bone.

For a specimen too thick to be submerged, you can use a turkey-baster to flood the difficult areas. I treated an adult mammoth tibia that, because of its size, I dried in the Florida sun, then used the baster to pump consolidant into every opening of the bone.

I use a RubberMaid-type cake-pan to hold the consolidant for this soaking step - that plastic seems to be impervious to the acetone. Get 'em at your local dollar-store.

Acetone evaporates very quickly. Replenish the consolidant mixture with a bit of acetone if you are using it on many specimens. Store it in a tightly sealed glass jar. Even if some acetone evaporates away between uses (it always does, it seems), you can reconstitute the solution by replacing the acetone.

Acetone is a nasty solvent. The fumes are explosive. The fumes are toxic. The liquid penetrates the skin-blood barrier. It's best to use gloves. Use in a well-ventilated area.

--------------Harry Pristis"

* Here's what 'oilshale' had to say about white glue:

"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"

[JpaIowa]

This is great stuff guys, Thanks for all the advice. This is just a sample of the stuff I might find on a little adventure down the river. I'm not soo worried about the larger bones and vertebra, but like the hoof core, upper jaw section (of whatever it is) and various teeth and things of that nature I feel are maybe more fragile. I think I might try the duco cement and acetone method, both of those ingredients seem pretty available. Can I just brush it on to larger items instead of dunking, to avoid having to make so much of the consolidant?

[Harry Pristis]

This is great stuff guys, Thanks for all the advice. This is just a sample of the stuff I might find on a little adventure down the river. I'm not soo worried about the larger bones and vertebra, but like the hoof core, upper jaw section (of whatever it is) and various teeth and things of that nature I feel are maybe more fragile. I think I might try the duco cement and acetone method, both of those ingredients seem pretty available. Can I just brush it on to larger items instead of dunking, to avoid having to make so much of the consolidant?

The idea is to penetrate the micro-spaces in the bone, so brushing on a consolidant is not getting the job done. You can't buy less than a pint of acetone, and a tube of DUCO Cement is what . . . about $2.00?

[JpaIowa]

Did a few small test pieces in the duco cement and acetone. Bison 1st phalanx- went well. Bison lower 3rd molar- not as well. It bubbled like hell, as it was in the consolidant I could see the bubbles lifting little flakes off of the root portion of the tooth. After being taken out and allowed to dry the root was very dry and crumbly. I did it on the same tooth again today and it got worse. Maybe not the consolidant to use in that situation? The root of the tooth was dry and not real stable prior to the treatment, but way better than it is now. Any suggestions?

[Harry Pristis]

Did a few small test pieces in the duco cement and acetone. Bison 1st phalanx- went well. Bison lower 3rd molar- not as well. It bubbled like hell, as it was in the consolidant I could see the bubbles lifting little flakes off of the root portion of the tooth. After being taken out and allowed to dry the root was very dry and crumbly. I did it on the same tooth again today and it got worse. Maybe not the consolidant to use in that situation? The root of the tooth was dry and not real stable prior to the treatment, but way better than it is now. Any suggestions?

Anytime you dry and re-wet bone/tooth material you run the risk of dislodging already-loose material. Without consolidation with a plastic, some of these pieces are likely to just disintegrate in your drawer.

If the tooth root is still crumbly after soaking it in consolidant, you should try using more DUCO and less acetone in your solution. This is something you should approach on a trial and error basis. Don't scrimp on the plastic, or you'll be wasting your time.

[JpaIowa]

Good points. Thanks Harry!