Is Elmers School glue really not removable from fossils?

[VRFossils]

I'm a little confused.  On the forums I have read a number of times (at least I thought I did) that Elmers school glue cannot be removed from a fossil, once it has dried.  But just for the sake of experimenting, I coated a small rock in elmers glue and let it dry.  After it sat in the warm sun for awhile and was good and dried, I put it in water.  And almost immediately, the glue softened up and turned white and sticky again.  I let it soak for awhile and then washed it off.  The Elmers glue washed right off.

 

Did I miss something?  Or an I experimenting with the wrong kind of glue?

 

I know Elmers glue is not very recommended for coating fossils, but I just got curious and wanted to experiment. :-)

So if anybody can fill me in, that would be great!

[Harry Pristis]

 

What is the point of your experiment?  That is, what application do you anticipate for school glue in preparing fossils?  

 

I suspect you are confusing 'school glue,' a formulation that allows the reversal of children's accidents, with typical 'white glue.'  Perhaps @oilshale is in a position to comment.

 

 

[Mark Kmiecik]

Elmers glue and Elmers school glue are two different products. There are many adhesives marketed under the "Elmers" logo. Google and read the wikipedia info. They make every kind from casein and PVA to cyanoacrylate types.

[oilshale]

White glue usually consists of a dispersion - tiny polymer particles (diameter ~1µm)  of polyvinyl acetate in water. To achieve high water resistance and good shear strength, N-methylolacrylamide (a monomer that can react as a crosslinker) is polymerized onto the surface of the polymer particles. When the water evaporates, the polymer particles - the polyvinyl acetate - melt into a polymer film and the N-metylolacrylamide begins to crosslink the polymer chains. The polymer chains will form a three-dimensional network that can still swell in solvents such as acetone, but is no longer fully soluble.

 

Elmers school glue is a special formulation that deliberately has a very low water resistance, is redispersible with water and can easily be washed out of soiled / glued clothing.

 

Wood glue should not be confused with PVA B15 beads (trademark for example Vinac). Both materials consist mainly of polyvinyl acetate, but the PVA beads do not contain N-methylolacrylamide as a crosslinker and therefore are permanently soluble in acetone or other solvents.

 

SPNHC Leaflets: A Technical Publication Series of the Society for the Preservation of Natural History Collections

"ADHESIVES AND CONSOLIDANTS IN GEOLOGICAL AND PALEONTOLOGICAL CONSERVATION: A WALL CHART"

Wall Chart - Adhesives and Consolidants.pdf

[Mark Kmiecik]

You learned that you can use the "school glue" for adhering things either temporarily or things that you are not sure will work as planned and may need to be undone until you have a sure-fire method developed and a permanent adhesive or a more robust adhesive can be used. In most cases fossils need no coating or repair and coating them just to make them look "shiny" diminishes both the monetary and scientific value of the specimen. If you look at specimens displayed at museums you'll notice that only the specimens that absolutely need it have any adhesive used and in most cases its only function is to keep them from falling apart.

[Harry Pristis]

2 hours ago, Mark Kmiecik said:

 In most cases fossils need no coating or repair and coating them just to make them look "shiny" diminishes both the monetary and scientific value of the specimen. If you look at specimens displayed at museums you'll notice that only the specimens that absolutely need it have any adhesive used and in most cases its only function is to keep them from falling apart.

.

Ahem!!  . . .  Mark 

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.

[Mark Kmiecik]

16 hours ago, Harry Pristis said:

.

Ahem!!  . . .  Mark 

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.

I look at my post and it says "most". So what you are saying is that these types of fossils would absolutely need it, correct? To keep them from "falling apart"? That is what I said. I also said that coating fossils to make them "shiny", like they did in the old days with Mazon Creek specimens using albumin, subtracts from their value. There's no point in clearcoating every fossil you find is the point I thought I had made.

 

Sorry, I didn't mean to confuse anyone.

[VRFossils]

Ok, yeah, the explanation of the difference between "Elmers school glue" (which is usually white) and the actual "white glue" helps clear things up! 

 

So I understand now why school glue can be dissolved in water, but "white glue" cannot.

 

Thanks!

[Harry Pristis]

25 minutes ago, Mark Kmiecik said:

I look at my post and it says "most". So what you are saying is that these types of fossils would absolutely need it, correct? To keep them from "falling apart"? That is what I said. I also said that coating fossils to make them "shiny", like they did in the old days with Mazon Creek specimens using albumin, subtracts from their value. There's no point in clearcoating every fossil you find is the point I thought I had made.

 

Sorry, I didn't mean to confuse anyone.

 

What I said, Mark, was that you cannot tell which vertebrate fossil might be damaged by the stresses of drying, and that a wise curator will impregnate (not "coat"!!) all those fossils, thus forestalling the probabilities that some of them would otherwise split or fall apart.  It sounds like you think all fossils are from Mazon Creek . . . clearcoating is not a term I hear when talking about vertebrate fossils. 

[Ptychodus04]

With the ease of procuring proven conservation grade materials like Paraloid B72, Butvar B76, and Rhoplex WS24 (for wet specimens), I continue to be amazed that we regularly have these conversations about using white glue, wood glue, lacquers, etc. for fossil conservation. These have unknown long term stability concerns at best and some have known long term issues. Why would you temporarily glue anything fossil related with school glue when you can use Paraloid B72 or Butvar B76 to glue it, both of which are 100% reversible with acetone indefinitely? Using school glue even for this can have serious consequences.

 

For example, let's say to have some Pleistocene mammal bone you are repairing and you're not sure how the fit works. In scenario 1, you slather on some school glue, put the pieces together, clamp and let the glue dry. Once dry, you have a poorly bonded bone that fits together. Now, you have to soak it in water to de-bond the substandard joint you created. Most fossil bone is extremely hydrophilic and you remove your de-bonded bone fragments from their soak and set them out to dry. Later, you return to find your bone in dozens of pieces since it broke apart while drying due to the nature of fossil bone. In scenario 2, you slather on some Paraloid or Butvar, put the pieces together, clamp and let the glue dry. Once dry, you have a well bonded bone that fits together... End of story.

 

Let's say that your bone fragments don't go together as well as planned and you have to de-bond the plastic. You soak the whole thing in acetone, take out the fragments, and let them dry without worry of the utter destruction you caused by using water.

 

I'm with @Harry Pristis on the consolidation of vertebrate remains. When I was prepping in the Perot lab, we didn't touch a fossil bone without a bottle of low viscosity Butvar solution as our side. Every bone I work on in my lab gets a hearty dose of Paraloid B72 to consolidate it. Even fossil bone that appears stable isn't really stable. They are almost looking for an excuse to fall apart.

 

 

[Randyw]

5 hours ago, Ptychodus04 said:

With the ease of procuring proven conservation grade materials like Paraloid B72, Butvar B76, and Rhoplex WS24 (for wet specimens), I continue to be amazed that we regularly have these conversations about using white glue, wood glue, lacquers, etc. for fossil conservation

+1. I recently got my first order of paraloid b72 and i was surprised at how easy and cheap to get it really was.

[Wrangellian]

On 10/4/2019 at 11:24 AM, Ptychodus04 said:

With the ease of procuring proven conservation grade materials like Paraloid B72, Butvar B76, and Rhoplex WS24 (for wet specimens), I continue to be amazed that we regularly have these conversations about using white glue, wood glue, lacquers, etc. for fossil conservation.  stable isn't really stable. They are almost looking for an excuse to fall apart.

 

I can't speak for the OP but I think a lot of people are unaware of B72 etc, but everyone is aware of white glue and probably a lot of them assume it is OK for rock/fossils... like I did in the beginning. It was only upon reading here on the Forum and interacting with you guys that I learned about Paraloid/Acryloid/B72. So I doubt you'll ever see the end of these questions.

I have stopped using white glue since getting a package of Acryloid but many of my older fossils were reassembled or strengthened with white glue (WeldBond) going back 10 years or more, so I've got the chance to observe what happens with them over time. Most of them are OK but I notice several gaps that seem to have separated a little, and I'm not sure that the WeldBond hasn't expanded a bit with air humidity, or if they have split due to some fault in the rock such as pyrite, or if those gaps were already that far apart when I glued them and I just didn't have the exacting standards that I now have in making sure they're tight (I have trouble believing this). If I only knew whether any sort of white glue (in particular WeldBond) does in fact expand with air humidity, but if this is the case, why has it not happened with all of them?

[VRFossils]

Just to clarify, I wasn't planning to use school glue to consolidate fossils.  I've read the discussions about it on the forums.  So I know it's not a good idea.  The only reason I asked the question was because I was a little puzzled over what I read.  I didn't know that "white glue" was different from white school glue, which I knew could be dissolved in water.  Anyway, that's cleared up now.

 

As far as the availability of Paraloid and Butvar, I've kind of had a hard time finding it in small quantities for a cheap price.  I have a few dinosaur bone pieces to consolidate (nothing too valuable), and I don't want to spend more than $10.  I found some small quantities on Etsy for a good price. 

 

They have Paraloid B67 - 

And Butvar B90 - 

And Paraloid B72 - 

 

The bones I have are fairly stable.  They were laying on top of the ground at the excavation site for months or years, before I picked them up.  So they are fairly solid.  But I want to put them on display where kids can touch them (schools and fairs).  So I want something that will still look fairly natural but put a good coating on the outside to protect them from skin oil.  It would be an added benefit if it could be disolved later in acetone, just in case I had some reason to, but I that's not so important.

So given those qualifiers, does anybody have any suggestions which of the above products on Etsy would be best to use for this type of purpose?  Or does anybody know of other sources with similar prices?

Edited October 7, 2019 by JohnJ
Sales links removed

[Randyw]

9 hours ago, Wrangellian said:

can't speak for the OP but I think a lot of people are unaware of B72 etc,

Actually that’s a good point and one we tend to forget I think. I had never heard of paraloid or the other compounds before I joined here so it’s actually a good question from a learner or newcomer standpoint

[Ptychodus04]

@VRFossils you want to go with the Paraloid B72. 

[JohnJ]

Temporal sales links removed.  

[Al Tahan]

I use Elmer’s glue on almost all my fossils......not for repair...but for “show” and “protection”. I put them on my trilobites, Eurypterids, phyllocarids as a last measure. I just make a thin mix with water so it’s a cloudy white mixture (I use a black plate so I can see the density of glue better). I apply with a small brush and let it dry. It gives a better contrast to the matrix and washes off every time. It’s not over the top and if you think you went to think you can just wash off with warm water end try again. I’ve had Elmer’s glue on a trilobite for years and it still washed off. I know some people use the matte finish finisher of some kind but I like that the Elmer’s glue is forgiving.  I wouldn’t use it to actually hold a fossil together but it’s great for aesthetics. 

[Huntonia]

I hadn't heard of consolidating vertebrate fossils with paraloid b72 before today. I have a partial mastodon tooth that I'm pretty fond of, it's pretty solid feeling in hand but it has quite a few cracks along the surface and one that's quite deep. Would it be worthwhile to soak it in a paraloid-acetone mixture? If so how can I best do so and how will it affect the look of the piece?

[Ptychodus04]

6 hours ago, Huntonia said:

I hadn't heard of consolidating vertebrate fossils with paraloid b72 before today. I have a partial mastodon tooth that I'm pretty fond of, it's pretty solid feeling in hand but it has quite a few cracks along the surface and one that's quite deep. Would it be worthwhile to soak it in a paraloid-acetone mixture? If so how can I best do so and how will it affect the look of the piece?

Inspect your tooth well to ensure there aren’t any glue joints before you soak it or it will fall apart in the solution.

 

If there are no joints, mix a solution if 1 part Paraloid to 50 parts acetone measured by weight and submerge the tooth until the bubbles stop coming out.

 

Remove and set tooth on cardboard overnight. The tooth may be a little more shiny afterwards. If this is undesirable, take a clean, low lint rag and wet it with acetone. Rub the surface to remove the top layer of Paraloid from the tooth. 

 

Well preserved enamel is very nonporous so the Paraloid won’t penetrate well but it will penetrate deeply into the cracks.

[Harry Pristis]

I feel self-conscious when I post this in another thread, but it seems that the "About Me" page on my Forum Profile is not enough exposure.

 

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.

Butvar B-76 and other suitable plastics, such as Vinac, are more frequently available on the Internet these days. But, if you can't find Butvar-76 or Vinac, you may want to fall back on a solution of Duco Cement (clear, like model airplane glue) in acetone. Duco Cement is not a first choice, or even a second; but, it will hold a fossil together while you consider other options.

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.

(From this point, the techniques are the same for any plastic consolidant you choose.) 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 surmise. (A microwave oven may be as effective, but I've only dried glass beads for my air-abrasive unit.) Residual moisture may cause a white film to develop on the surface of a fossil after dipping in the consolidant.

Here's how the white film forms: As the acetone in the consolidant evaporates, the temperature at the surface of the specimen chills abruptly, lowering the dew-point at which ambient water vapor condenses.

 

And, that's my theory -- that the white film has two potential sources: residual interstitial moisture and ambient humidity condensing at the surface chilled by evaporation.

   Think about a plastic bag of food placed into a freezer, where frost is moisture and bag is the film of consolidant. Frost can form on either or both sizes of the plastic bag, inside frost from moisture in the food and outside frost from atmospheric moisture.

   My solution is heating the specimen to drive off residual moisture, and consolidating while it is warm to increase the dew-point at the specimen's surface, inhibiting condensation as the acetone boils off.

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 10-30 seconds, or until the specimen stops fizzing). Set each wet specimen aside to dry on cardboard (I use a beer-flat because that cardboard is absorbant and doesn't readily stick to the fossil).

To avoid pooling of consolidant which may 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 container to hold the consolidant for this basting 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 (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"

 

 

[Huntonia]

Thanks for the info. I have read your instructions on consolidating I just wanted to make sure it would work well on the mastodon tooth. I have a few questions though. 1 will 16oz of acetone be enough, it's one cusp from a relatively small mastodon. 2 would a basic heating lamp work to dry the tooth? (I'm a bit wary to stick it in the microwave). 3 how long does the acetone-paraloid solution take to dry. I live in Oregon and it is often cold or rainy and I doubt I will get more than a day of good sunlight at a time for the next few months.

[Harry Pristis]

 

Yes, 16 fl. oz. of acetone should be plenty for multiple fossils.

 

Any infra-red lamp should do the trick, an allthemore important step in a humid invironment.

 

The fossil is dry enough to handle in just a few minutes.  Allow several hours for all the acetone to boil off.

[Huntonia]

During the time the acetone is boiling off will it smell strongly? I wouldn't want to leave it outside too long but at the same time I wouldn't want my house to be full of acetone fumes. For removing the fossil from the acetone mixture would garden gloves be alright or should I use rubber gloves?

[Ptychodus04]

27 minutes ago, Huntonia said:

During the time the acetone is boiling off will it smell strongly? I wouldn't want to leave it outside too long but at the same time I wouldn't want my house to be full of acetone fumes. For removing the fossil from the acetone mixture would garden gloves be alright or should I use rubber gloves?

It will smell until all of the acetone has evaporated. That usually takes several hours. Use gloves that don’t allow the acetone to touch your skin. It really doesn’t matter the exact type.

[Huntonia]

When I consolidate the mastodon tooth should I also consolidate my equus horse tooth and spinosaurus tooth or will they be okay without?