Protective Coatings

[CreekCrawler]

What product would be the best to preserve shark teeth roots and echinoids like a Macraster? Is there a specific shellac or coating that is best?

thanks

B

[Xiphactinus]

What product would be the best to preserve shark teeth roots and echinoids like a Macraster? Is there a specific shellac or coating that is best?

thanks

B

Don't coat unless something is really in danger of falling apart. If you do need to, I suggest dilute Vinac. It will penetrate the fossil, not just coat it. If dilute enough, it won't change the appearance of the fossil at all. You can order it through the mail from the Black Hills Institute of Geologic Reasearch (the guys who found Sue the T-Rex)

[Harry Pristis]

What product would be the best to preserve shark teeth roots and echinoids like a Macraster? Is there a specific shellac or coating that is best?

thanks

B

Don't coat fossils! That is the general rule. Don't use shellac or polyurethane or laquer or anything with "hiding" properties. (You want good hiding in a house paint, for example.)

Generally, shark teeth and echinoids (or any invertebrate fossils) should not be treated with anything. Bones are routinely consolidated -- some require it, some highly-mineralized bones may not.

For an unusual circumstance, what you may want is a consolidant -- a thin solution of plastic which will penetrate a fossil specimen and bolster its internal structure. As the solvent vehicle evaporates away, the plastic is left behind to line the voids and pores, providing an artificial endo-skeleton. The consolidant binds together weak components and stabilizes micro-fractures that later might become problems if left untreated.

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 consolidation is a polyvinyl butyral plastic such as Butvar-76, but that material is hard to find in small quantities. I have used this plastic, dissolved in acetone, for many types of fossils. It works quite nicely on bones or on Silurian-age shales with brachiopods. It penetrates well, and in the proper dilution it produces a "damp-looking" finish with no gloss.

So, what works best? I recommend a solution of Duco Plastic Glue (clear, like model glue) in acetone. (It was $0.97/ounce yesterday in WalMart.)

Dilution? Start with a one-ounce tube of glue dissolved in about eight ounces of acetone in a glass jar. Stir or 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!

Ideally, you would submerge the dry specimen in this consolidant for a brief time (say 20-30 seconds, or until the specimen stops fizzing). Set each wet specimen aside to dry on cardboard (I use beer-flats).

For a specimen too large 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

[Cody]

Wow i hope you use that snakekeeper,im sure that took harry a long @$$ time to type that.I hope it works though.I would vote against gluing or anything,keep it au naturale.

[tomclark]

Yeah, what Harry said! Exactly.

Fizzy Fizzy! No Shiny!~

[CreekCrawler]

Thanks guys, the reason that I asked is because while in a creek I found a sharks tooth still in part of the matrix. Well since it was wet I decided to pull away some of the matrix with my fingers"big no-no" half of the root came off with the matrix! Funny thing is that I had a small bottle of clear nail polish in my backpack.I just should have collected and wrapped it up for working on at home. "Lesson Learned"

[Harry Pristis]

Well, here at the museum I work for, our final step in bone prep (note, we are mainly dealing with Edmontosaurus annectens fossils, but in general it's Cretaceous age dino bits) is a thin coating of either Vinac or Acryloid. Both start out as tiny, clear plastic beads.

A jar full of acetone is the base, and then a heaping spoonful of beads are poured in and the mixture is shaken until all the beads dissolve. For a thicker mixture, cut down on the acetone and up the amount of beads. Personally, I go for a more dilute mixture myself. MUCH less shine that way.

Wm.T.

I don't want to argue the meaning of "coat" here. For the purpose of this thread can we agree that you put a coat of paint on a house? The paint adheres to the siding, creating a hide or film, but doesn't penetrate deep into the wood. The coat may bubble, and after weathering, it may need to be scraped off with a putty knife so that it can be repainted.

That is not what we do with vertebrate fossils.

Vinac or Acryloid or Butvar-76 in a thin solution with acetone is a consolidant intended, not to coat the fossil, but to penetrate and make the fossil material more durable. It does this by depositing a plastic endo-structure in the pores and spaces within the fossil.

(In a thicker solution, these plastics may be use as an adhesive to hold pieces of bone together.)

I don't know about your dino bits, WmT., but I think most preparators seek to minimize the coating while maximizing the penetration.

Fizzy Fizzy! No Shiny!

[Harry Pristis]

Thanks guys, the reason that I asked is because while in a creek I found a sharks tooth still in part of the matrix. Well since it was wet I decided to pull away some of the matrix with my fingers"big no-no" half of the root came off with the matrix! Funny thing is that I had a small bottle of clear nail polish in my backpack.I just should have collected and wrapped it up for working on at home. "Lesson Learned"

I'm confused. What does a bottle of clear nail polish in your backpack have to do with breaking off the root of the shark tooth??

I do understand your dismay. I have had to console myself occasionally with the thought, "It was broken anyway -- before I did anything -- and would have crumbled/cracked/broken in the prep lab with no avoiding it!"

There are more matrix pieces to be found! Good hunting!

[RJB]

I know how some fossil folks like to keep things all natural, and I also know how some fossils really do need some kind of stabilizer to keep them intact. There really is lots of different types of glues and such and a bit of knowledge to know which type of glue or such to use with what type of fossil of hows its been fossilized in order to 'save' it, but im the type of guy who likes to enhance the fossils that I prep with glytal or vinac. After prepping out a fossil crab or lobser, I then apply a very thin coat of these glues to really bring out the fossil! The difference is night and day!!! and not only that, but it seals the fossil and keeps the oxigen in the air from doing any more damage and also keeps any flaky parts from comming off later in time. also, if its an important scientific fossil, both glyptal and vinac can be taken off. In fact, if I remember, I will take before and after photos of the next crab I do to show you folks the difference. Thar ya go.

RB

[Auspex]

I really like the varied responses in this thread! To me, the big message is that you want to determine just what it is that you want to accomplish BEFORE you apply any technique or material.

"If you don't know where you're going, you could end up someplace else."

[tracer]

I've found several good articles through Google on consolidating various types of fossils. I worry more about stuff found in or near salt water. I usually soak it a while and let some of the salt come out if what I'm trying to conserve might be damaged by salt crystalization. I've read that unknown formulations of commercial products shouldn't be used because you can't know how to undo what's been done should you have something rare and a better consolidant come along years from now. So, for instance, if you use pure PVA in acetone, you know what it is and how to deal with it going forward. If, on the other hand, you use XYZ Wonderglue, it may be a great product but what's in it and how do you get it off, or is that even possible?

Having said all that, I tend to use Vinac and sometimes cyanoacrylate glue, if I use anything at all. I probably shouldn't mention this for purists, but if you're going to try to make something super stable to say, make jewelry out of it, there are lapidary-type epoxies that become super hard and super clear. Some people seal porous lapidary material, like cut dino bone or petrified wood, so that it will polish well if it isn't perfectly agatized.

Regards,

Tracer

[jax]

Thanks guys, the reason that I asked is because while in a creek I found a sharks tooth still in part of the matrix. Well since it was wet I decided to pull away some of the matrix with my fingers"big no-no" half of the root came off with the matrix! Funny thing is that I had a small bottle of clear nail polish in my backpack.I just should have collected and wrapped it up for working on at home. "Lesson Learned"

I do this alot it seems while prepping teeth in matrix. Personally I use the clear liquid nails. Theres a hobby type tube. Just put a tiny bit on there and it works perfect. Just dont put too much cause it will seep out.

[flyguy784]

When I worked in engineering we needed absolute penetration of a silicon material on our sensors. Now mind you we were using a relatively inert silicon potting matterial. To achieve full penetration we'd use a vacume sealer, like you use to seal vegatables. Put the part in the partialy (one end) sealed bag, put in enough liquid to cover part, then vacumize. It would pull every bit of air out of the part replacing that air with the liquid. The result was absolute penetration of the material. I'd be concerned about pumping acetone fumes but for any water based product I'll bet it would work on fossils as well. It was amazing how well that sytem achieved penetration.

Just a thought.

[Ramo]

You "just happened" to have some nail polish. Don't tell us you also "just happened" to have some lipstick, rouge, woman's dress, etc. also. What you do (and wear) out in the field is your business, not ours.

[Auspex]

You "just happened" to have some nail polish. Don't tell us you also "just happened" to have some lipstick, rouge, woman's dress, etc. also. What you do (and wear) out in the field is your business, not ours.

In southern chigger country, clear nail polish is essential survival gear! I learned that leading birding tours in the lower valley.

[Eureka]

Dear friends,

Please, could you let me know if every time you use glyptal or vinac are applied 100% pure directly on the surface of the crab with a brush or

dissolves them in acetone.

If a dissolution becomes, what´s the proportion? for instance, 90% acetone and 10% glyptal.

Thanks in advance for the answers.

PD: RJB could you post the after and before of a fossil crab after apllying glyptal.....

Eureka