To Seal Or Not To Seal?

[CH4ShotCaller]

Started working on one 'less-than-par' concretion today. I have caused some slight damage on the left claw and that raised a question. After I finish the prep, should I use some sort of protective sealant or leave well enough alone? Thanks for any advice!

[Texas-Tunnel Rat]

Im sure this may or may not work, I never seal my stuff due to it ruining possible research data.

But I hear dipping it in watered down stuff like Super Glue works to keep a protective film on things.

[CH4ShotCaller]

Thanks! Since this piece is a 'test' project, I'll give 'er a try.

[anablep]

Vinac works well temporarily while you work on it.

[Missourian]

Temporary seal - Only if fossil won't become damaged upon removal of seal.

Permanent seal - Only if the fossil will flake away if left unprotected.

[Opisthotriton]

There are three main types of consolidants/glues used in professional fossil preparation.

1) Reversible plastic-based (eg polyvinyl acetate) consolidants dissolved in acetone or alcohol: Commonly referred to as Vinac or Butvar. There are many slight variations on the plastic formula, and slight pros/cons to each formula. Basically, with fossils, Vinac or Butvar are both fine. White glue (Elmer's) is a similar formula, but with proprietary formula differences. Vinac and Butvar are among the "safest/most reliable" for long-term preservation. Products like Elmer's white glue have unknown formulas, and are not recommended for long-term preservation. That said, for the casual collector who may want a cheap and easy glue for fossils that are common and not worth major investment of time/money, Elmer's could be perfect for your needs. It is simple, cheap, and easy to use. Vinac and Butvar are purchased as tiny plastic beads, and you dissolve them in acetone (sometimes alcohol, generally people use acetone) to get the desired thickness. A thin vinac/butvar solution will penetrate bone, bringing the plastic deep inside. When the acetone evaporates, the plastic remains, consolidating the bone. A thick solution can be used as glue to hold pieces together, but it does not have much strength. The best reason to use vinac/butvar is because they are REVERSIBLE. They can always be re-dissolved in more acetone, so if you make a mistake, you can reverse it, take pieces apart, and then glue them again. White glue is not perfectly reversible; it can be partially removed, but with a lot of effort and possible damage to the fossil.

2) Superglue (cyanoacrylate): Common and cheap, but beware that every brand of superglue uses a slightly different proprietary formula, most of which have not been tested for long-term preservation. If you're serious about fossil preparation, and will need a lot of superglue, invest in a paleo-approved brand like Paleobond. Thin superglue, like thin vinac, can penetrate a bone deeply and consolidate it very well. Thick superglue can glue pieces together very strongly. So strongly, in fact, that if the rest of the bone has not been consolidated with thin superglue or vinac, and the bone later breaks again, it will break next to your glue joint instead of breaking the glue. Superglue is NOT reversible. Once you've glued to pieces together, they're stuck. If you later find a shard of bone that belongs in between the two pieces, you will have to physically crack the glue joint apart. There are some scary chemicals that can weaken dried superglue and partially remove it, but these do not make it truly reversible. Overall, superglue is great for fossils, just be absolutely sure you're ready for a permanent bond. If you pour some thin superglue on the surface, and it dries before penetrating, then you will never be able to get superglue down deep into the bone, because it will be blocked by the first layer of superglue. Vinac is better, because the acetone in it can partially dissolve a previous layer of vinac, allowing it to penetrate below the first layer.

3) Epoxy (eg, 2-part 15-minute liquid epoxy tubes): Again, every brand has a different formula, and few (none?) have been tested for long-term preservation. Still, they are very commonly used. Epoxy is most useful when you want to glue together two large pieces that have a bit of a gap between them in places. Epoxy is much more bulky than vinac or superglue, so it can fill gaps while also gluing them together fairly strongly.

NEVER mix superglue or vinac with water! The ONLY glue that can mix well with water is Elmer's white glue (preferably the water-soluble "washable" kind), and as mentioned above, it's not your best option. Make sure that your fossils are completely dry before using superglue or vinac. Vinac/butvar are acetone-based, and acetone hates water. If your fossil is still wet, the vinac will not be able to penetrate the bone. The vinac will sit on the surface, and react with the water, turning white, gooey, and bubbly. It will look similar to Elmer's white glue, but will take days (at least!) to dry properly, and may always stay soft and opaque. If superglue meets water, it will make a nasty reaction and end up white, crusty, brittle, and full of bubbles.

Vinac: http://www.bhigr.com/store/product.php?productid=262

Paleobond "superglues": http://paleobond.com/Getting_Started_Kit_info.html

So, to answer your original question: Although it does depend on your fossil and its preservation, generally the safest method is to protect the fragile area with vinac. This will keep all pieces in their place, and hopefully help keep new cracks from forming. When you are finished prepping, you can remove the vinac from the surface with acetone, and can take the pieces apart if needed. Then you can use vinac or superglue to preserve it permanently.

[CH4ShotCaller]

Thanks everybody for taking the time to post some help! Great information to help me in my struggle of crab conc grinding. This Forum and it's members are a bunch of very good folks!

[Steph]

On 12/1/2011 at 3:50 PM, Opisthotriton said:

There are three main types of consolidants/glues used in professional fossil preparation.

1) Reversible plastic-based (eg polyvinyl acetate) consolidants dissolved in acetone or alcohol: Commonly referred to as Vinac or Butvar. There are many slight variations on the plastic formula, and slight pros/cons to each formula. Basically, with fossils, Vinac or Butvar are both fine. White glue (Elmer's) is a similar formula, but with proprietary formula differences. Vinac and Butvar are among the "safest/most reliable" for long-term preservation. Products like Elmer's white glue have unknown formulas, and are not recommended for long-term preservation. That said, for the casual collector who may want a cheap and easy glue for fossils that are common and not worth major investment of time/money, Elmer's could be perfect for your needs. It is simple, cheap, and easy to use. Vinac and Butvar are purchased as tiny plastic beads, and you dissolve them in acetone (sometimes alcohol, generally people use acetone) to get the desired thickness. A thin vinac/butvar solution will penetrate bone, bringing the plastic deep inside. When the acetone evaporates, the plastic remains, consolidating the bone. A thick solution can be used as glue to hold pieces together, but it does not have much strength. The best reason to use vinac/butvar is because they are REVERSIBLE. They can always be re-dissolved in more acetone, so if you make a mistake, you can reverse it, take pieces apart, and then glue them again. White glue is not perfectly reversible; it can be partially removed, but with a lot of effort and possible damage to the fossil.

2) Superglue (cyanoacrylate): Common and cheap, but beware that every brand of superglue uses a slightly different proprietary formula, most of which have not been tested for long-term preservation. If you're serious about fossil preparation, and will need a lot of superglue, invest in a paleo-approved brand like Paleobond. Thin superglue, like thin vinac, can penetrate a bone deeply and consolidate it very well. Thick superglue can glue pieces together very strongly. So strongly, in fact, that if the rest of the bone has not been consolidated with thin superglue or vinac, and the bone later breaks again, it will break next to your glue joint instead of breaking the glue. Superglue is NOT reversible. Once you've glued to pieces together, they're stuck. If you later find a shard of bone that belongs in between the two pieces, you will have to physically crack the glue joint apart. There are some scary chemicals that can weaken dried superglue and partially remove it, but these do not make it truly reversible. Overall, superglue is great for fossils, just be absolutely sure you're ready for a permanent bond. If you pour some thin superglue on the surface, and it dries before penetrating, then you will never be able to get superglue down deep into the bone, because it will be blocked by the first layer of superglue. Vinac is better, because the acetone in it can partially dissolve a previous layer of vinac, allowing it to penetrate below the first layer.

3) Epoxy (eg, 2-part 15-minute liquid epoxy tubes): Again, every brand has a different formula, and few (none?) have been tested for long-term preservation. Still, they are very commonly used. Epoxy is most useful when you want to glue together two large pieces that have a bit of a gap between them in places. Epoxy is much more bulky than vinac or superglue, so it can fill gaps while also gluing them together fairly strongly.

NEVER mix superglue or vinac with water! The ONLY glue that can mix well with water is Elmer's white glue (preferably the water-soluble "washable" kind), and as mentioned above, it's not your best option. Make sure that your fossils are completely dry before using superglue or vinac. Vinac/butvar are acetone-based, and acetone hates water. If your fossil is still wet, the vinac will not be able to penetrate the bone. The vinac will sit on the surface, and react with the water, turning white, gooey, and bubbly. It will look similar to Elmer's white glue, but will take days (at least!) to dry properly, and may always stay soft and opaque. If superglue meets water, it will make a nasty reaction and end up white, crusty, brittle, and full of bubbles.

Vinac: http://www.bhigr.com/store/product.php?productid=262

Paleobond "superglues": http://paleobond.com/Getting_Started_Kit_info.html

So, to answer your original question: Although it does depend on your fossil and its preservation, generally the safest method is to protect the fragile area with vinac. This will keep all pieces in their place, and hopefully help keep new cracks from forming. When you are finished prepping, you can remove the vinac from the surface with acetone, and can take the pieces apart if needed. Then you can use vinac or superglue to preserve it permanently.

Wow - super helpful. I joined the forum a few weeks ago, but I came across this post today from a google search and it is still helpful 11 years later.  Thank you! 

[Ptychodus04]

Materials update...

 

Vinac is almost impossible to find these days as it has been out of production for several years. Also, it is less desirable than Paraloid B72 or Butvar B76 as it gets really soft at temps above 90 degrees. Paraloid is much harder and stable at higher temps. 

[Steph]

12 hours ago, Ptychodus04 said:

Materials update...

 

Vinac is almost impossible to find these days as it has been out of production for several years. Also, it is less desirable than Paraloid B72 or Butvar B76 as it gets really soft at temps above 90 degrees. Paraloid is much harder and stable at higher temps. 

Yes- I soon realized that it was tough to find. Thanks for the update!