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Butvar Vs Duco


megaholic

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Hi everyone.

I just joined up, and I want to get right to it. I want to start a discussion about the two schools of thought for fossil consolidants. I have been using Duco Cement in acetone for a while with fair results. I have some very nice recent finds however, that are fairly soft and I am considering the expense of Butvar 76 instead for their preservation. I do not find that the Duco is producing the hardness I would like, and would welcome any other opinions from those who have used both. It has become rather difficult to find a reasonable price for a small amount of Butvar lately. I find $23 for a kilo and $17 for shipping excessive! I would never even consider the use of anything water based, so let's just explore the two options... :unsure:

"A man who asks is a fool for five minutes. A man who never asks is a fool for life".

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B-76 for $17.00 for a kilo (2.2 lbs) sounds really cheap. I have purchased it from Talas (talasonline.com) in the past and have paid 17.50 per lb. The shipping sounds about right for FED EX ground in the US.

Now as to the two -

Remember B-76 is completely (or almost completely) reversible. Since it is usually dissolved in acetone, once the resin sets up it can be re-dissolved using acetone. This is particularly handy if you happen to connect the wrong pieces together - trust me it happens - usually late at night and lack of sleep factored in.

B-76 since it comes in a solid form doesn't get old on the shelf.

1 Lb of Butvar 76 will last you a very long time. (see next item)

B-76 goes a long way. Since it is a dissolvable resin, you can make it in the thickness that you desire. You can make it very thin in order to penetrate the fossil and consolidate it. You can make it a bit thicker to use as a semi-soft set glue and finally you can make it very thick and use it like a webbing. There is an interesting paper (I do not have access to it here at work) that describes using it to build a spiderweb to fill in a hole in a very fragile mammal jaw.

B-76 can be used in the field; however I caution that it should be used sparingly. When repairs are necessary in the field, you need to clean the area thoroughly as you will get matrix under the resin. Again since it is dissolvable in acetone, you can remove it and the glued on matrix back at the lab but it is generally a pain in the butt to do so. We have stopped using it in the field except in the most extreme cases.

DUCO cement is exactly that - cement/glue. Once it sets - it is set. The problem that I have had in the past with cyanoacrylic glues is that when they bond, they are sometimes stronger than the material around them. If you are forced to separate the two pieces, you may not get it to separate at the original break but have a second break. . . which really doesn't look that good (personal experience).

Cement/glue also tends to run outside of the parts you are wanting to attach. As a prepper in the lab, I hate trying to remove over run glue from the specimen. It tends to be a very tedious job therefore I have (successfully for the most part) banned it from our dig sites.

Now Butvar 76 is also dissolvable in ethanol alcohol. The benefit you get with ethanol is that it takes longer to evaporate; therefore if you are trying to consolidate a thicker item, you get better penetration since the alcohol will carry the resin deeper into the specimen than acetone.

The sum of my advice -

Bite the bullet - buy the Butvar-76.

leave the DUCO cement at home for repairing snarge around the house.

Roger

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if you use the search function on this forum to look for discussions on this subject you will find a number of them. if you do the math to calculate the total cost per ounce of consolidant solution using different products, you may well find that the solvent you choose is much more of an issue than the polymer or copolymer.

there are no similarities between some of the products people choose to compare. in my mind, they are not analogs. others are. proprietary products aside, it will always be my strong suggestion to people that they simply use a search engine to look for and read up on the actual chemistry and properties of anything they are considering putting on their fossils. if your fossils don't matter that much, then do whatever with them. but if they do, and you really value them, and you can't just go out and find others just like them, then consider yourself a curator of something cool that others would like to appreciate long after you won't be able to any more, and consider trying to make that possible. especially in situations where it doesn't take much more effort to do so.

some materials and chemicals became famous long ago for being "good" because they were the best things available at the time they became famous. time has marched on and things progress. so go ask ANY art museum conservator if they think you should be slapping cellulose nitrate on any of your prized possessions. they spend all their time trying to get stuff like that OFF important things so they can be preserved with more reversible, stable, and even safer copolymers. and a big deal is that the consolidant used is of KNOWN formulation. what's IN a commercial, proprietary formulation? nobody really knows exactly. so you get wild one day and grab wifey's large economy size nail polish remover thinking it's just acetone and you'll buy her another bottle to replace the one you're ripping off to use to mix up some consolidant with. well, some companies put moisturizers in nail polish remover to counteract the drying action of the acetone after it's sucked the lipids out of wifey's skin. did you want silky smooth moisturized fossils? (note to tj - that was a hypothetical question).

it's been a loooooooonnnnnnnggggg day - stress, breakfast of champions!

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Back in my earkly days, I collected using Duco to consolidate the pieces of a jawbone. I haven't unnwrappeed it in almost 30 years. I shuould go find it and see how it looks. Meanwhile, avoid Duco on fossils. tracer and Roger have both spoken well. I personally use Vinac B-15 in the field. That's what I was trained on,and that's what I use. Unlike Roger, I do use cyanoacrylate in the lab, unless the fit is questionable.

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Thank you for the great advise. The Duco cement I am using is not a ca glue, but I believe it is the same type polymer as Butvar. It looks and smells like the old Ambroid model cement we tried to use sparingly on our hobby projects. I am only trying to use it as a consolident.

And that leads me to the question of using it on shark teeth to prevent splitting and to stop cracks from worsening. Is it helpfull to just consolidate the root?

"A man who asks is a fool for five minutes. A man who never asks is a fool for life".

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The Duco cement I am using is not a ca glue, but I believe it is the same type polymer as Butvar.

i think there was a bit of confusion further up the topic. but none of the three things you've mentioned in the sentence above are even remotely similar to each other in my mind. that was my point before. they are VERY different things with VERY different characteristics.

i did not discuss CA glue before. CA glue is becoming very widely used for certain things because of it's properties. i do use it on fossils some and i've got specific reasons for what i do with it. a discussion of it could get fairly long though so punting for the moment.

one key to trying to figure out what a product actually is can be the MSDS safety sheet for the product. it will not tell the whole story in every case, but in many cases it will help show what's in the product by the standard chemical names as opposed to a single brand name.

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Thanks Tracer.

I was refering to the comment about ca made by Roger above. I personally have many years of ca glue experience in the hobby industry. I have at least 3 different thicknesses of ca at all times in my fridge for my other hobby of crashing and rebuilding R/C planes. Since I can't fly very good, I have become a pretty good builder. I can see the complexity of a discussion on this already, because of my prior experiences with it. I really wanted to compare apples to apples, and I think the Butvar and Duco are just that. I am going to drop the Duco consolidation and bite the bullet and try some Butvar. I am sure that will lead to yet another discussion. I have been taking your advise and searching the subject. I see I am not the first to explore this idea.

"A man who asks is a fool for five minutes. A man who never asks is a fool for life".

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Thanks Tracer.

I was refering to the comment about ca made by Roger above. I personally have many years of ca glue experience in the hobby industry. I have at least 3 different thicknesses of ca at all times in my fridge for my other hobby of crashing and rebuilding R/C planes. Since I can't fly very good, I have become a pretty good builder. I can see the complexity of a discussion on this already, because of my prior experiences with it. I really wanted to compare apples to apples, and I think the Butvar and Duco are just that. I am going to drop the Duco consolidation and bite the bullet and try some Butvar. I am sure that will lead to yet another discussion. I have been taking your advise and searching the subject. I see I am not the first to explore this idea.

Roger was confused about the nature of Duco Cement. He is also confused when he writes this logical non-sequitur:

Now Butvar 76 is also dissolvable in ethanol alcohol. The benefit you get with ethanol is that it takes longer to evaporate; therefore if you are trying to consolidate a thicker item, you get better penetration since the alcohol will carry the resin deeper into the specimen than acetone.

Certainly, rate of evaporation has no relevance to the depth of penetration. Alcohol is just less-toxic to use. The downside is that alcohol evaporates less-rapidly than acetone, a feature that may slow-down commercial or museum preparation.

I do agree with Roger about using Butvar-76 (or some equivalent plastic) whenever possible. I have written many times here recommending Duco and acetone, but that is because they are easy to work with and accessible to the casual collector. The preferred commercial or museum consolidant remains Butvar-76 in acetone or perhaps a PVA (other than Elmer's glue).

http://pristis.wix.com/the-demijohn-page

 

What seest thou else

In the dark backward and abysm of time?

---Shakespeare, The Tempest

 

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I just found this on the Texas A&M site. It is quoted from the underwater preservation dept head;

CELLULOSE NITRATE

Cellulose nitrate, formerly called nitrocelluloid, has a long history of use in conservation. Recently it has, to a large degree, been

replaced by other synthetic resins. Cellulose nitrate is still used, especially as an adhesive. It has many of the same characteristics of

PVA, but it is not internally plasticized as are most PVAs. Therefore, cellulose nitrate has a much greater tendency than PVA to

become brittle, crack, and peel off.

Cellulose nitrate is soluble in acetone, methyl ethyl ketone, and esters, such as amyl acetate and n-butyl acetate. Since it is not

soluble in alcohols, e.g., ethanol and methanol, it is useful on compound objects requiring different consolidating resins with different

solvents. A plasticizer is required to prevent the resin from becoming too brittle.

There are a number of proprietary adhesives on the market that utilize cellulose nitrate. Duco cement is one example that is

marketed in the USA. Duco cement is cellulose nitrate dissolved in acetone and butyl acetate, with oil of mustard added as a

plasticizer. Because of its availability, Duco has been used extensively, with varying success, in pottery reconstructions and general

artifact mending. Duco is easy to use and is effective in the short run, but over the years, the glue may yellow and become brittle,

resulting in the breakup of glued items. It is not recommended for use in archaeological conservation (Moyer 1988b; Feller and Witt 1990).

"A man who asks is a fool for five minutes. A man who never asks is a fool for life".

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I just found this on the Texas A&M site. It is quoted from the underwater preservation dept head;

CELLULOSE NITRATE

Cellulose nitrate, formerly called nitrocelluloid, has a long history of use in conservation. Recently it has, to a large degree, been

replaced by other synthetic resins. Cellulose nitrate is still used, especially as an adhesive. It has many of the same characteristics of

PVA, but it is not internally plasticized as are most PVAs. Therefore, cellulose nitrate has a much greater tendency than PVA to

become brittle, crack, and peel off.

Cellulose nitrate is soluble in acetone, methyl ethyl ketone, and esters, such as amyl acetate and n-butyl acetate. Since it is not

soluble in alcohols, e.g., ethanol and methanol, it is useful on compound objects requiring different consolidating resins with different

solvents. A plasticizer is required to prevent the resin from becoming too brittle.

There are a number of proprietary adhesives on the market that utilize cellulose nitrate. Duco cement is one example that is

marketed in the USA. Duco cement is cellulose nitrate dissolved in acetone and butyl acetate, with oil of mustard added as a

plasticizer. Because of its availability, Duco has been used extensively, with varying success, in pottery reconstructions and general

artifact mending. Duco is easy to use and is effective in the short run, but over the years, the glue may yellow and become brittle,

resulting in the breakup of glued items. It is not recommended for use in archaeological conservation (Moyer 1988b; Feller and Witt 1990).

Of course, we are not talking here about archaeological conservation.

I am surprised and disappointed in your attention to what you're reading, 'megaholic'. If you'd been paying attention, you'd have included the final paragraph of the section which you quote above. Here it is (with emphasis added):

Cellulose nitrate is discussed here because of its availability and general misuse in many [archaeological] conservation projects. In a few given cases, it may be necessary to use several resins with mutually exclusive solvents to consolidate some complex object. The use of cellulose nitrate is in this case is only on a temporary basis and should be removed and substituted with a longer lasting, reversible resin. Cellulose nitrate should never be used as a glue.
While it still has its drawbacks, diluted Duco can be used to stabilize material such as bone by impregnation. For dilution purposes, Duco has approximately 0.8 grams of resin per one gram of stock mix in the tube.

http://pristis.wix.com/the-demijohn-page

 

What seest thou else

In the dark backward and abysm of time?

---Shakespeare, The Tempest

 

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Thanks Tracer.

I was refering to the comment about ca made by Roger above. I personally have many years of ca glue experience in the hobby industry. I have at least 3 different thicknesses of ca at all times in my fridge for my other hobby of crashing and rebuilding R/C planes. Since I can't fly very good, I have become a pretty good builder. I can see the complexity of a discussion on this already, because of my prior experiences with it. I really wanted to compare apples to apples, and I think the Butvar and Duco are just that. I am going to drop the Duco consolidation and bite the bullet and try some Butvar. I am sure that will lead to yet another discussion. I have been taking your advise and searching the subject. I see I am not the first to explore this idea.

i can tell you that even what i consider the top two "current" products for fossil consolidation, both of which i use, have very different properties in a way. while you're researching stuff, be sure to look up one of the most important properties of polymers, "glass transition temperature". this is a big deal for us. cross-linking is a big deal also.

i have not found any perfect copolymer yet. but i use polyvinyl butyral, polyvinyl acetate, and cyanoacrylate 99% of the time. and quite a bit of acetone. and on occasion an aqueous emulsion on a wet, falling-apart fossil that i think won't survive drying. but then again i don't bring most of those home.

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OK Harry P.

Thanks for the direction. I did miss that detail when quoting the above. I love it when a knowledgeable person stands on a valid point of discussion. When the personal thoughts on a subject are conveyed to others we all gain the value of the experience shared. This is so often missing in printed articles on subjects due to the ever present threat of loss of advertisers, or sponsors. This is one of the primary reasons I joined TFF.

"A man who asks is a fool for five minutes. A man who never asks is a fool for life".

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Roger was confused about the nature of Duco Cement. He is also confused when he writes this logical non-sequitur:

Now Butvar 76 is also dissolvable in ethanol alcohol. The benefit you get with ethanol is that it takes longer to evaporate; therefore if you are trying to consolidate a thicker item, you get better penetration since the alcohol will carry the resin deeper into the specimen than acetone.

Certainly, rate of evaporation has no relevance to the depth of penetration. Alcohol is just less-toxic to use. The downside is that alcohol evaporates less-rapidly than acetone, a feature that may slow-down commercial or museum preparation.

I do agree with Roger about using Butvar-76 (or some equivalent plastic) whenever possible. I have written many times here recommending Duco and acetone, but that is because they are easy to work with and accessible to the casual collector. The preferred commercial or museum consolidant remains Butvar-76 in acetone or perhaps a PVA (other than Elmer's glue).

Roger is correct. A slower evaporation rate gives the solvent a longer time to drag the polymer into the substrate. Hence, DEEPER penetration. A consolident which stays on the surface only is not a very good consolident in that it needs depth of penstration to impart structural integrity to the substrate. This is my approach:

I use B-72 just because I have it. B-76, although chemically different, is functionally the same. I use a 3% solution in acetone with 10% ethanol (ethyl alcohol) as a consolident. The slower evaporation rate imparted by the ethanol gives the polymer more time to soak into the substrate.

For gluing, I use 10% - 50% B-72 in acetone, depending on the desired thickness. As an adhesive you'd like the evaporation to be rapid so that you don't need to stabilize the pieces being glued for too long.

For wet substrates I use 10-20% Elmer's Glue All in water as a consolident.

Hope this helped.

Tom

AVOCATIONAL PALEONTOLOGIST

STROKE SURVIVOR

CANCER SURVIVOR

CURMUDGEON

"THERE IS A VERY FINE LINE BETWEEN AVOCATIONAL PALEONTOLOGY AND MENTAL ILLNESS"

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one of the most difficult issues regarding consolidation of fossils is the lack of immediate feedback on the result. you do something, get finished, and feel a sense of satisfaction at having "preserved" your treasure for the ages. but the reality is that over the decades, some "jobs" will hold up really well and some won't.

so i know i'm not going to get much feedback from my fossils for quite some time regarding how well they will last. the way i counter that lack of information is to study as much as i can about the materials and techniques and the long-term results others have had.

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Roger is correct. A slower evaporation rate gives the solvent a longer time to drag the polymer into the substrate. Hence, DEEPER penetration. A consolident which stays on the surface only is not a very good consolident in that it needs depth of penstration to impart structural integrity to the substrate. This is my approach:

I use B-72 just because I have it. B-76, although chemically different, is functionally the same. I use a 3% solution in acetone with 10% ethanol (ethyl alcohol) as a consolident. The slower evaporation rate imparted by the ethanol gives the polymer more time to soak into the substrate.

For gluing, I use 10% - 50% B-72 in acetone, depending on the desired thickness. As an adhesive you'd like the evaporation to be rapid so that you don't need to stabilize the pieces being glued for too long.

For wet substrates I use 10-20% Elmer's Glue All in water as a consolident.

Hope this helped.

Tom

Uhhh . . . No, I don't think it helped, Tom.

Let me re-state my conclusion so that there is no further confusion: The rate of evaporation has no relevance to the depth of penetration when you soak a bone in consolidant.

When you describe "a longer time to drag the polymer into the substrate", it sound as though you are applying the consolidant to the exterior with a brush. If you are merely painting a bone exterior with consolidant, you're unlikely to get the best-possible results.

(I've posted instructions for a dipping technique more than a few times on TFF, so I won't repeat them here. And, I've described how I consolidated a mammoth tibia, a bone too bulky to dip. Most mammal bones are more easily treated.)

I know nothing of Butvar-72. When the Howard Converse described the use of Butvar-76 at the Florida State Museum, he claimed that none of the Butvar formulations except for B-76 was acetone-soluble. Is that the reason you use 10% ethanol in your consolidant solution? Are you certain you have B-72 and not B-76 ?

http://pristis.wix.com/the-demijohn-page

 

What seest thou else

In the dark backward and abysm of time?

---Shakespeare, The Tempest

 

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I didn't have any indication that this thread was strictly concerning bones. I have no experience with bones, I primarily work with much older critters.

Your original statement:

"Certainly, rate of evaporation has no relevance to the depth of penetration. Alcohol is just less-toxic to use. The downside is that alcohol evaporates less-rapidly than acetone, a feature that may slow-down commercial or museum preparation."

As you can see....no bones were mentioned. I was trying to rectify the statement that "..rate of evaporation has no relevance to the depth of penetration." ....when It most certainly does.

As for what B-72 is, Its trade name is Paraloid and it is produced by Rohm & Haas and it is an ethyl methacrrylate copolymer. As I said before, the chemistry is different from B76 but the functionality is the same. It's the only consolidant / adhesive used by the Burke Museum.

You also said.....

"I know nothing of Butvar-72. When the Howard Converse described the use of Butvar-76 at the Florida State Museum, he claimed that none of the Butvar formulations except for B-76 was acetone-soluble. Is that the reason you use 10% ethanol in your consolidant solution? Are you certain you have B-72 and not B-76 ?"

Butvar refers to a family of polymers produced by Monsanto and, you are correct, within this family the only one which is soluble in acetone is B76.

I am quite sure that what I work with is B72 because I got it from the manufacturer....Rohm & Haas.

The only reason for adding ethanol to my consolidant solution is to slow the rate of evaporation and increase the penetration into the substrate.

I find that B72 is extremely versatile (as I'm sure B76 is also). A solution of any viscosity can be produced by mixing varying amounts of acetone and B72.. It is easily reversed (removed) with acetone. Its evaporation rate can be modified with ethanol. This last feature is useful in its use as a consolidant to vary the penetration but also as an adhesive to vary the viscosity from very thin to very thick depending on the nature (size) of the needed repair.

Tom

Uhhh . . . No, I don't think it helped, Tom.

Let me re-state my conclusion so that there is no further confusion: The rate of evaporation has no relevance to the depth of penetration when you soak a bone in consolidant.

When you describe "a longer time to drag the polymer into the substrate", it sound as though you are applying the consolidant to the exterior with a brush. If you are merely painting a bone exterior with consolidant, you're unlikely to get the best-possible results.

(I've posted instructions for a dipping technique more than a few times on TFF, so I won't repeat them here. And, I've described how I consolidated a mammoth tibia, a bone too bulky to dip. Most mammal bones are more easily treated.)

I know nothing of Butvar-72. When the Howard Converse described the use of Butvar-76 at the Florida State Museum, he claimed that none of the Butvar formulations except for B-76 was acetone-soluble. Is that the reason you use 10% ethanol in your consolidant solution? Are you certain you have B-72 and not B-76 ?

AVOCATIONAL PALEONTOLOGIST

STROKE SURVIVOR

CANCER SURVIVOR

CURMUDGEON

"THERE IS A VERY FINE LINE BETWEEN AVOCATIONAL PALEONTOLOGY AND MENTAL ILLNESS"

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I didn't have any indication that this thread was strictly concerning bones. I have no experience with bones, I primarily work with much older critters.

Your original statement:

"Certainly, rate of evaporation has no relevance to the depth of penetration. Alcohol is just less-toxic to use. The downside is that alcohol evaporates less-rapidly than acetone, a feature that may slow-down commercial or museum preparation."

As you can see....no bones were mentioned. I was trying to rectify the statement that "..rate of evaporation has no relevance to the depth of penetration." ....when It most certainly does.

As for what B-72 is, Its trade name is Paraloid and it is produced by Rohm & Haas and it is an ethyl methacrrylate copolymer. As I said before, the chemistry is different from B76 but the functionality is the same. It's the only consolidant / adhesive used by the Burke Museum.

You also said.....

"I know nothing of Butvar-72. When the Howard Converse described the use of Butvar-76 at the Florida State Museum, he claimed that none of the Butvar formulations except for B-76 was acetone-soluble. Is that the reason you use 10% ethanol in your consolidant solution? Are you certain you have B-72 and not B-76 ?"

Butvar refers to a family of polymers produced by Monsanto and, you are correct, within this family the only one which is soluble in acetone is B76.

I am quite sure that what I work with is B72 because I got it from the manufacturer....Rohm & Haas.

The only reason for adding ethanol to my consolidant solution is to slow the rate of evaporation and increase the penetration into the substrate.

I find that B72 is extremely versatile (as I'm sure B76 is also). A solution of any viscosity can be produced by mixing varying amounts of acetone and B72.. It is easily reversed (removed) with acetone. Its evaporation rate can be modified with ethanol. This last feature is useful in its use as a consolidant to vary the penetration but also as an adhesive to vary the viscosity from very thin to very thick depending on the nature (size) of the needed repair.

Tom

Tom, I'm not trying to embarrass you; but, you are confused about your resin.

There is a Butvar-72, but that is not what you are using. You are using Paraloid B-72. Both "Butvar" and "Paraloid" are trade names for different plastic resins made by different manufacturers.

Butvar-76 is polyvinyl butyral.

Paraloid B-72 is a methyl acrylate/ethyl methacrylate copolymer.

The rest is semantics. When Roger said "alcohol will carry the resin deeper into the specimen", it didn't make any sense to me. Then you mentioned "substrate", and that's when I understood that I needed to specify that I was talking about bones, which I did.

All the references in this thread to specific things to be consolidated are vertebrate remains: "jaw bones," "shark teeth," and "diluted Duco can be used to stabilize material such as bone by impregnation." Now, please tell us what you are using Paraloid to consolidate.

http://pristis.wix.com/the-demijohn-page

 

What seest thou else

In the dark backward and abysm of time?

---Shakespeare, The Tempest

 

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Tom, I'm not trying to embarrass you; but, you are confused about your resin.

There is a Butvar-72, but that is not what you are using. You are using Paraloid B-72. Both "Butvar" and "Paraloid" are trade names for different plastic resins made by different manufacturers.

Butvar-76 is polyvinyl butyral.

Paraloid B-72 is a methyl acrylate/ethyl methacrylate copolymer.

The rest is semantics. When Roger said "alcohol will carry the resin deeper into the specimen", it didn't make any sense to me. Then you mentioned "substrate", and that's when I understood that I needed to specify that I was talking about bones, which I did.

All the references in this thread to specific things to be consolidated are vertebrate remains: "jaw bones," "shark teeth," and "diluted Duco can be used to stabilize material such as bone by impregnation." Now, please tell us what you are using Paraloid to consolidate.

OMG !!! What have I gotten myself into?

Look Harry....all I wanted to do was help out megafossil with some suggestions and instead, I've become embroiled in this debate.

I don't understand why you re-state my comments and then make it sound like I disagree with my own thoughts.

Everything I've said about B72 and it's properties is true. Adding ethanol to a solution of acetone and B72 will slow the rate of evaporation and result in a deeper penetration into the substrate. This is all useful information (at least it was to me) that will assist anyone working with this type of product.

I'm primarily working with the following substrates which at times require consolidation of the matrix: shale and sandstone. There are times that the fossil itself requires consolidation as well.

I primarily work on marine invertebrates and plants.

Please, no more picky little arguments. Let's just allow anyone who desires it to pull what they want from the information presented.

Signing off.

Tom

AVOCATIONAL PALEONTOLOGIST

STROKE SURVIVOR

CANCER SURVIVOR

CURMUDGEON

"THERE IS A VERY FINE LINE BETWEEN AVOCATIONAL PALEONTOLOGY AND MENTAL ILLNESS"

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OMG !!! What have I gotten myself into?

Look Harry....all I wanted to do was help out megafossil with some suggestions and instead, I've become embroiled in this debate. ...

Don't blow a fuse, Tom. You injected a note of confusion into the thread (you confused me, at least), and now we've got the chemistry and semantics straightened out. Your contribution did help; it forced further explication of an important subject.

ACRYLOID B-72

Acryloid B-72 (referred to as Paraloid B-72 in Europe) is a thermoplastic acrylic resin manufactured by Rohm & Haas, which has replaced PVA in many applications and is preferred by many conservators over PVA. It is a methyl acrylate/ethyl methacrylate copolymer and is an excellent general-purpose resin. Durable and non-yellowing, Acryloid B-72 dries to a clear transparency, with less gloss than PVA, and is resistant to discoloration even at high temperatures. It is very durable and has excellent resistance to water, alcohol, alkalis, acid, mineral oil, vegetable oils, and grease, and it retains excellent flexibility.

Acryloid B-72 can be applied in either clear or pigmented coatings by a variety of application methods and can be air dried or baked. It has a very low reactivity with sensitive pigments. Furthermore, it is compatible with other film-forming materials, such as PVA and cellulose nitrate, and can be used in combination with them to produce stable, transparent coatings with a wide variety of characteristics. In stronger concentrations, Acryloid B-72 can be used as a glue (see Koob 1996 for details). This glue formulation is the standard glue used at the Conservation Research Laboratory at Texas A&M University.

Acryloid B-72 is unique in possessing a high tolerance for ethanol, e.g., after being dissolved in acetone or toluene, up to 40 percent ethanol can be added to the solution to control the working time. This property allows its use in applications where strong solvents cannot be tolerated. The alcohol dispersion may be cloudy or milky; however, clear, coherent films are formed upon drying.

http://pristis.wix.com/the-demijohn-page

 

What seest thou else

In the dark backward and abysm of time?

---Shakespeare, The Tempest

 

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Don't blow a fuse, Tom. You injected a note of confusion into the thread (you confused me, at least), and now we've got the chemistry and semantics straightened out. Your contribution did help; it forced further explication of an important subject.

ACRYLOID B-72

Acryloid B-72 (referred to as Paraloid B-72 in Europe) is a thermoplastic acrylic resin manufactured by Rohm & Haas, which has replaced PVA in many applications and is preferred by many conservators over PVA. It is a methyl acrylate/ethyl methacrylate copolymer and is an excellent general-purpose resin. Durable and non-yellowing, Acryloid B-72 dries to a clear transparency, with less gloss than PVA, and is resistant to discoloration even at high temperatures. It is very durable and has excellent resistance to water, alcohol, alkalis, acid, mineral oil, vegetable oils, and grease, and it retains excellent flexibility.

Acryloid B-72 can be applied in either clear or pigmented coatings by a variety of application methods and can be air dried or baked. It has a very low reactivity with sensitive pigments. Furthermore, it is compatible with other film-forming materials, such as PVA and cellulose nitrate, and can be used in combination with them to produce stable, transparent coatings with a wide variety of characteristics. In stronger concentrations, Acryloid B-72 can be used as a glue (see Koob 1996 for details). This glue formulation is the standard glue used at the Conservation Research Laboratory at Texas A&M University.

Acryloid B-72 is unique in possessing a high tolerance for ethanol, e.g., after being dissolved in acetone or toluene, up to 40 percent ethanol can be added to the solution to control the working time. This property allows its use in applications where strong solvents cannot be tolerated. The alcohol dispersion may be cloudy or milky; however, clear, coherent films are formed upon drying.

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Tom

AVOCATIONAL PALEONTOLOGIST

STROKE SURVIVOR

CANCER SURVIVOR

CURMUDGEON

"THERE IS A VERY FINE LINE BETWEEN AVOCATIONAL PALEONTOLOGY AND MENTAL ILLNESS"

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I don't want to add fuel to the fire (discussion is already getting a little bit too hot). I am a polymer chemist by profession - so I am just talking about chemistry:

Butvar is Solutia's tradename for a whole group of Polyvinyl butyral resins (PVB). But there are also other producers of Polyvinyl butyral resins such as DuPont, Wacker Chemie with Pioloform as tradename (that is the company I am working for), Sekisui and Kuraray (Mowital).

PVB is very stable against UV degradation and yellowing (it is used in laminated or safety glass for windshields). The softening point is quite high - so it will not get sticky at higher temperatures. The actual composition can vary; the more butyral groups in the polymer, the poorer the solubility in acetone. Butvar 76 has a rather low amount of butyral groups. Adding some Ethanol (10% or so) will lower the evaporation rate of Acetone - makes sense to me (but be careful, don't add to much Ethanol - the polymer isn't soluble any more). I am using ethyl acetate as a solvent. The boiling point is higher and the toxicity is lower compared to acetone (and I love the fruity smell).

Paraloid was the tradename of Rohm and Haas. Since DOW acquired Rohm and Haas in 2008, the tradename has changed and is now Acryloid. Under Acryloid, a whole group of different product is subsumed. Acryloid B72 for example is an ethyl methacrylate polymer, B67 is an isobutyl methacrylate polymer and B76 is a methyl methacrylate ethyl methacrylate copolymer. You can buy almost the same products under other tradenames from other producers such as BASF or DuPont.

Methacrylates are also very stable against UV degradation and yellowing. The softening point depends on the actual composition and can be quite high. Methyl methacrylate has a Tg of around 125°C, the softening point of ethyl methacrylate is somewhat lower but still high enough to prevent stickiness. The solubility of the polymers depends on the composition; the higher the amount of ethyl or butyl groups - the poorer the solubility in polar solvents such as ethanol / acetone mixtures.

For consolidating I prefer either Acryloid B76 or B72. Since the company I am working for is a PVB producer (and I can get samples for free) I also use PVB a lot.

The more hydrophobic B67 is excellent for sealing fossils after treatment with ethanolamine thioglycolate to prevent pyrite / marcasite rot.

Thomas

Be not ashamed of mistakes and thus make them crimes (Confucius, 551 BC - 479 BC).

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Though scientific vs. personal use sometimes is dependent on the user sometimes we often take things too literal. Mentioning what works for you and how you use the tools and or chemicals is a lively topic as we have seen here for sure. The facts can be obtained from the web and here on items used but as I am learning throughout the history of preparation there have been a lot of great advances in the science. The uses of consolidates and the like has changed over the years. Many of us are new to this science and we are trying to find out what to use and how to use them yes, often times the MSDS sheets tell you what the substances are how to use them this is academic for sure but I find personal ideas and how a person uses them are just as important. Note I do not need to get into argument with anyone but this forum is for the sharing and presentation of ideas and information for us new guys please do not make it a place where people are afraid to ask questions gentlemen and ladies.

James Underwood

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I don't want to add fuel to the fire (discussion is already getting a little bit too hot). I am a polymer chemist by profession - so I am just talking about chemistry:

Butvar is Solutia's tradename for a whole group of Polyvinyl butyral resins (PVB). But there are also other producers of Polyvinyl butyral resins such as DuPont, Wacker Chemie with Pioloform as tradename (that is the company I am working for), Sekisui and Kuraray (Mowital).

PVB is very stable against UV degradation and yellowing (it is used in laminated or safety glass for windshields). The softening point is quite high - so it will not get sticky at higher temperatures. The actual composition can vary; the more butyral groups in the polymer, the poorer the solubility in acetone. Butvar 76 has a rather low amount of butyral groups. Adding some Ethanol (10% or so) will lower the evaporation rate of Acetone - makes sense to me (but be careful, don't add to much Ethanol - the polymer isn't soluble any more). I am using ethyl acetate as a solvent. The boiling point is higher and the toxicity is lower compared to acetone (and I love the fruity smell).

Paraloid was the tradename of Rohm and Haas. Since DOW acquired Rohm and Haas in 2008, the tradename has changed and is now Acryloid. Under Acryloid, a whole group of different product is subsumed. Acryloid B72 for example is an ethyl methacrylate polymer, B67 is an isobutyl methacrylate polymer and B76 is a methyl methacrylate ethyl methacrylate copolymer. You can buy almost the same products under other tradenames from other producers such as BASF or DuPont.

Methacrylates are also very stable against UV degradation and yellowing. The softening point depends on the actual composition and can be quite high. Methyl methacrylate has a Tg of around 125°C, the softening point of ethyl methacrylate is somewhat lower but still high enough to prevent stickiness. The solubility of the polymers depends on the composition; the higher the amount of ethyl or butyl groups - the poorer the solubility in polar solvents such as ethanol / acetone mixtures.

For consolidating I prefer either Acryloid B76 or B72. Since the company I am working for is a PVB producer (and I can get samples for free) I also use PVB a lot.

The more hydrophobic B67 is excellent for sealing fossils after treatment with ethanolamine thioglycolate to prevent pyrite / marcasite rot.

Thomas

Thanks, Thomas, for another lucid explanation for us chemistry-challenged collectors.

What you say about Butvar B-76

Butvar 76 has a rather low amount of butyral groups. Adding some Ethanol (10% or so) will lower the evaporation rate of Acetone - makes sense to me (but be careful, don't add too much Ethanol - the polymer isn't soluble any more0.

conflicts with what I've read about this resin. I have read that Butvar B-76 is soluble in both acetone and in ethanol. If that's not correct, I need to make a notation in the margin of my preparation handbook.

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