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#1 greel

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Posted 27 May 2009 - 02:44 PM

I read Harry's excellent post on using Duco glue and acetone as fossil preservative. He mentions using a Duco

plastic or model glue in a tube. I found a Duco cement in a small bottle - will this substitute for the tube?


-greel

#2 RJB

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Posted 27 May 2009 - 03:45 PM

That will work. Its not as good as other glues though. Duco has a low % of solids compaird to other glues too. But its what I started out with for the first 5 or 6 years i was prepping. Once I found Glyptal i fell in love with it. A much better glue, but you have to buy it by the quart wich is expensinve, but it will make over a gallon of glue depending on how you mix it. You will want some acitone to mix with your duco also. I dont kow what your prepping, but you want to mix it thinner for stabilizing soft stuff and a bit thicker for other things adn not at all if you just want to glue two pieces of something back together. Hope this helps.
RB

#3 Harry Pristis

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Posted 27 May 2009 - 04:14 PM

I read Harry's excellent post on using Duco glue and acetone as fossil preservative. He mentions using a Duco
plastic or model glue in a tube. I found a Duco cement in a small bottle - will this substitute for the tube?
-greel

I am not familiar with Duco Cement in a bottle. The stuff you want is water-clear cellulose acetate (IIRC) in the green tube. It's been around for a long time, and Wal-Mart had it for less than $1.50 per tube the last time I checked.

I believe that Duco makes other adhesives which you should avoid for consolidant purposes.


#4 jpbowden

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Posted 27 May 2009 - 07:10 PM

I think they used to sale Glyptal Resin in a powder form for Transformer repair, somewhere in Houston. Try the Thomas Book on this one but t was cheap. And it did dry clear!

#5 micropterus101

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Posted 03 June 2009 - 03:01 PM

found some info on glyptal while looking for supplier thaought I would pass it along.


From: San Diego Natural History Museum <libsdnhm@CLASS.ORG>

Definitely, you should stop the use of both Glyptal and shellac, as soon as possible, if in fact you are still using it. Both of them are highly unstable compounds. Shellac will continue to become more brittle and dark throughout its deterioration and can be very acidic, which is damaging in itself. Glyptal is part of the group of compounds derived from cellulose nitrate, which is notoriously unstable over time. They looked good when they were first put on, so people got into the habit of using them because they heard that someone else did, but the results 20 to 50 years later are disastrous. I have seen fossil destroyed by the physical damage caused when a join failed and allowed gravity to take over, and I have seen fossil surfaces pulled away from the bulk of the fossil by shrinkage of the polymer.



You ask about removing these. First of all, if at all possible (and it often isn't), figure out exactly what you are working with. Shellac cross-links over time. It starts out relatively easily soluble in ethanol, but becomes less and less so as it deteriorates. Glyptal should be soluble in the solvent that was originally used as the carrier, usually ethanol or acetone. Test a tiny area first. Second, do *not* dunk the specimens in a bath of solvent. It's unsafe for you, ineffective for the job, and may cause serious damage to the fossil. This is Q-tip work and can take time to do right. Use a fume hood or wear a respirator. The problem took a long time to develop and can't be fixed in an instant. You can use a hypodermic to do a controlled soaking of old joins of massive bones (but please be sure the barrel is not a plastic that will dissolve in your solvent. Yes, that is the voice of experience).



#6 bj aurora

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Posted 03 June 2009 - 07:15 PM

This might not be the right spot for this, but what DOES work well to stabalize fossils, if one doesn't have access to Butvar (or equivalent)? I have a permafrost walrus jaw from Alaska that needs to be stabalized and I am usure what to use. Someone said to use styrofoam in acetone, all I got was a clump of white goo in acetone. I know a white glue (like Elmers) mixed with water can stabalize smaller pieces, but what to use on larger ones?

#7 tracer

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Posted 03 June 2009 - 09:51 PM

well, i wasn't going to get back into a discussion like this, because i mentioned some time ago that cellulose nitrate isn't the way to go from quite a bit of literature. in my opinion it simply continues to be used because it was used before better consolidants were discovered. some even consider it dangerous. it is highly flammable. if your fossils are important to you, go to whatever relatively minor "hassle factor" is necessary to procure whatever bleeding edge consolidants exist at the time and are most recommended by professional conservators. you'll never find the same fossils again, so if you care about them, why take shortcuts in preserving them?

very basic and primary premises in consolidating fossils are that the process should be reversible and not harmful to the fossil, so that in the future things can be redone when better consolidants are available. crosslinking, yellowing, shrinking, and becoming brittle are all problematic.

although i believe the necessity for adhesives occasionally calls for epoxies and cyanoacrylates, consolidation seems to me to be best effected through the use of polyvinyl butyral and polyvinyl acetate. i see no reason to ever resort to using cellulose nitrate.

but then again, it's always risky to take advice from a fool, n'est-ce pas?
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#8 Harry Pristis

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Posted 03 June 2009 - 10:36 PM

This might not be the right spot for this, but what DOES work well to stabalize fossils, if one doesn't have access to Butvar (or equivalent)? I have a permafrost walrus jaw from Alaska that needs to be stabalized and I am usure what to use. Someone said to use styrofoam in acetone, all I got was a clump of white goo in acetone. I know a white glue (like Elmers) mixed with water can stabalize smaller pieces, but what to use on larger ones?

'bj aurora' . . . If you search the Forum for "consolidant", you'll find a wealth of information, some of it based on decades of experience with vertebrate fossils.

Here's one contribution to a thread entitled "Preserving Fossils":


Here is a workable technique for consolidating fossils.

Polyurethane will not give the desired penetration of the fossil. 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-76, but that material is 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-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? I recommend a solution of Duco Cement (clear, like model airplane glue) in acetone.

In a pinch, you can use a styrene plastic such as styrofoam dissolved in acetone. (I am not recommending this as I have no experience with styrene plastic. It is a tip I picked up years ago, but never needed to try.)

Dilution? Start with a tube of glue dissolved in about eight ounces of acetone in a glass jar. 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-flats).

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


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Posted 04 June 2009 - 05:37 AM

cellulose nitrate... some even consider it dangerous.


Is that gun cotton?

#10 tracer

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Posted 04 June 2009 - 06:49 AM

Is that gun cotton?


guncotton was based on it, yes, and so was film, and so was airplane wing dope, etc. and the fire threat was well known to movie houses, and many of the things that the material was used for no longer involve it. the material was also the primary component of "celluloid", which was one of the first "plastics" and was therefore used in a large number of things, including everything from writing pens to glues and lacquers.

it's use for most of the purposes has been curtailed, and i have read many negative comments about its long-term properties when used as a preservative.
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#11 Harry Pristis

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Posted 04 June 2009 - 10:34 AM

Lots of information here:

ADHESIVES AND CONSOLIDANTS


#12 greel

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Posted 04 June 2009 - 10:55 AM

Finally found a source for Duco cement in the green tube referenced by Harry. I couldn't find it at Wal-Mart

my local area, but found a good supply of it at Family Dollar - 1 dollar per tube. I searched Lowes, Home Depot,

Wal-Mart, Big Lots and several local hardware stores before I finally located it.


-greel

#13 oilshale

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Posted 18 August 2010 - 02:47 AM

Finally found a source for Duco cement in the green tube referenced by Harry. I couldn't find it at Wal-Mart

my local area, but found a good supply of it at Family Dollar - 1 dollar per tube. I searched Lowes, Home Depot,

Wal-Mart, Big Lots and several local hardware stores before I finally located it.


-greel



Don't know the stuff and never worked with it. I just saw the MSDS.
According to the Material Safety Data Sheet, Duco cement contains Cellulose Nitrate plus a (volatile) plasticizer (Camphor).

Acetone 60 - 100 by weight
Cellulose Nitrate 10 - 30 by weight
Isopropanol 1 - 5 by weight
1-methoxy-2-propanol acetate 1 - 5 by weight
Camphor 1 - 5 by weight

That's the stuff Tracer warned against...
Thomas

Edited by oilshale, 18 August 2010 - 02:49 AM.

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