Sealing Your Fossils?

[UnderwaterHunter]

what is the best way to clean fossils you have found under water? Ive herd 50% apple cider vinegar and 50% water. And to "seal them" to use either baby oil or 50% elmers glue and 50% water. Any new ideas or are those good??

[Harry Pristis]

On 5/22/2010 at 9:11 AM, UnderwaterHunter said:

what is the best way to clean fossils you have found under water? Ive herd 50% apple cider vinegar and 50% water. And to "seal them" to use either baby oil or 50% elmers glue and 50% water. Any new ideas or are those good??

You haven't said what sort of fossils you have in mind, and that makes a difference.

Vinegar has some limited applications. Straight vinegar might help oxidize bog iron crust (Goethite).  (Why use a pungent apple cider vinegar when white vinegar works just as well?)  Better to use straight Hydrogen Peroxide on algae crud.

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 bones and teeth, what you 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.  It is a nightmare to remove.

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? Plastics dissolved in acetone.

Down and dirty? A solution of Duco Plastic Glue (clear, like model glue) in acetone. (Duco was $0.97/ounce yesterday in WalMart.)

Dilution? Start with a half-ounce (volume) of plastic beads (or one-ounce tube of glue) dissolved in about eight ounces of acetone in a quart glass jar. Stir or shake well for an extended time.

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

[Seldom]

Good info Harry as always. Thanks

I use a hair dyer to dry and heat the fossil and do everything outside

[UnderwaterHunter]

Thanks Harry ill have to try it out. I found a mammoth spit tooth, and im guessing some kind of whale bone diving off venice, ill post pictures later so you guys can see them and identify them if im wrong.

[Rover]

The only fossil I've ever had to put a protective coating on was the Knightia in my avatar picture, which had started to flake away a little at the edges. I applied clear modeling glue (Tacky Glue, by brand) in a thin layer, and, while it's a little shiny, it doesn't hide the features of the fossil and it has protected it from further damage.

For any further protective coatings, though, I'll probably use the acetone/glue immersion method.

[Harry Pristis]

The only fossil I've ever had to put a protective coating on was the Knightia in my avatar picture, which had started to flake away a little at the edges. I applied clear modeling glue (Tacky Glue, by brand) in a thin layer, and, while it's a little shiny, it doesn't hide the features of the fossil and it has protected it from further damage.

For any further protective coatings, though, I'll probably use the acetone/glue immersion method.

Consolidant and vertebrate fossils go together! I wouldn't immerse a Green River fish, but I have no problem applying small amounts to stabilize such a fish. I did so, after consulting with the original preparer, to my Green River stingray.

[Stonebreaker]

How about things such as leaves or more importantly leaf imprints? And the best way to transport them home over a long distance? Should I seal them on site? Thanks for the advice and patience w/ all my endless questions. Should have some pics tomorrow of some thing I got this weekend.

[tracer]

underwaterhunter - hi and welcome

type the word "consolidant" in the search box on this forum and read every topic associated with it. may find a couple of links in those topics to outside info sources like "nautarch" which i've linked to before here.

you really asked two questions that each could have books written about them. fossil prep and fossil consolidation. big, complicated issues. i can say i've never used apple cider vinegar or baby oil on fossils.

lots of info on these subjects here and elsewhere on line.

[bear-dog]

Can't reply on the leaf imprints.As far as the bone and teeth,I use butvar and acetone.Many clubs sell it.Works great for me.Just make sure the fossil is dry first.If you get a milky look in an area just dab on some acetone,it goes away.Have tried the duco cement and acetone,works good but Im hooked on the butvar.For washing I use dawn dish soap and a finger nail brush.

Hope the info.helps. :beerhat:

[Megaselachus13]

What about the 96º alcohol to dilute instead of acetone?.

I usually dilute the paraloid B-72 and polyvinyl acetate in alcohol. Firstly because it is cheaper (here at least) and secondly by subject harmful vapors.

For now it works in my understanding.

[sweeneyb]

I mixed the duco with the acetone and once if dried it had white residue on it. You could see a build up of duco that looked like spider webs on it which peeled off. How do I remove all of it without ruining the fossil and also did I soak it too long for this to happen?

[bear-dog]

Sweeneyb,just read my reply above.If you get the milky white residue there was still moisture left in the fossil.Just dab on some acetone and it will go away.

[ashcraft]

How about things such as leaves or more importantly leaf imprints? And the best way to transport them home over a long distance? Should I seal them on site? Thanks for the advice and patience w/ all my endless questions. Should have some pics tomorrow of some thing I got this weekend.

I have coated leaf imprints with a number of things, painted on elmers/water mixture, painted on duco/acetone mixture. The best results I have achieved were with spray on finishes, like you can get at wal-mart. The cheaper the better (less coating, more solvent). I am getting ready to do some pleistocene leaves that actually "burn" on contact with air when split out of the clay. It was recommended to get art spray, like you would coat a pencil drawing with to keep from smearing, or hairspray, which will probably deal with moisture better. These, hopefully, will seal the freshly exposed specimens from the air and stop them from oxidizing.

Brent Ashcraft