First Time With Butvar-76

[Chamfer]

I got a kilo of Butvar-76 plastic from Museum Services Corporation, and slowly mixed a tiny amount into acetone following a 2.3 tablespoons to 800 ml ratio (about a 1:24 by volume) I found in an excellent post by Mattalic. Tonight I treated my first few fossils with it.

Some random observations on the process...

1) Everyone says when working with acetone to do so in a well-ventilated place, preferably outdoors. They say this for a very good reason. Don't be a dork (like me) and mix it indoors. I was queasy for several hours afterwards.

2) The largish (approx 6" diameter) glass jar I bought to hold/mix it in was not adequate. Or more accurately, it was too adequate. A smaller mason jar would have been a much better choice. I'll be going shopping soon.

3) The metal lid on the jar had a paper/plastic laminate liner. It almost immediately began to fall apart, and the jar leaked like crazy when shaking it, getting acetone all over the place. See item 1).

4) I want a magnetic stirrer.

5) Mattalic's suggested ratio of Butvar to acetone worked well. I think he nailed it.

6) I've got several hundred small specimens of neuropteris leaves and related material that I've painstakingly extracted from sixty or more pounds of crumbly weak shale in the past few months. Since this stuff is very soft, including fossils that are actually in clay, I've been treating them with PaleoBond stabilizer (to good effect). On some specimens I've coated the entire thing, while on others I've only stabilized the fossil, and not the surrounding matrix. This has resulted in a somewhat unattractive 'stained' appearance around each leaf. Soaking in the Butvar solution for 60-80 seconds removes this staining (and presumably at least some of the stabilizer), seems to make the fossil impressions slightly more contrasty to the matrix, and when dried gives the specimen overall a slightly plastic-feeling coating. I quite like the effect. I should take some before and after photos.

7) I've got a few dozen pieces of weak slate containing graptolites. It was this stuff that first set me off looking for ways to stabilize fossils, as washing them, not washing them, setting them on soft paper towels, and even looking at them funny would cause pieces of the slate to fall off. Very fragile stuff. So I dunked a couple of these in the Butvar solution, also for 60+ seconds. And now I know what the word 'delaminate' really means. The acetone seems to have an even more severe effect than water did, causing lots of splitting along fracture planes that weren't visible. I think with some care and experimenting this effect can be mitigated, and once dried the pieces did have improved strength. And I may intentionally try to delaminate some more, since one such split revealed a very nice graptolite that otherwise I'd never have seen.

Overall, largely thanks to a wealth of helpful information on these forums, my first foray into Butvar-76 went well. I'm looking forward to lots of additional batches.

[ZiggieCie]

[Auspex]

Solid feedback from personal experience!

This will be of great help for many folks to come

[jpc]

I use a magnetic stirrer for mixing vinac... it is a great addition to my aresenal. NIce post, btw.

[tooth_claw]

Another way to mix without a mag stirrer is to make a 'tea bag' from cheesecloth (or similar), put the dry ingredient in it and suspend it in the solution (keep the lid on!). This will dissolve (best left overnight) in a thin stream and reduce the need for actual stirring of the mixture.

[ZiggieCie]

Here is one of my favorite links for B-72 uses. All credits to the author, I just pass on the knowledge.

http://www.connectingtocollections.org/wp-content/uploads/2014/02/Davidson_and_Brown_2012_Paraloid_B-72-_Practical_tips_for_the_vertebrate_fossil_preparator.pdf

[DPS Ammonite]

I too used and liked Metallic's posted recipe. Use .525 teaspoon, (a slightly heaping 1/2 teaspoon), of Butvar 76 with 2oz/60ml of acetone in a 2oz/60ml Nalgene drop dispenser bottle. Shake on a off for a few minutes otherwise you will have a solid lump of plastic at the bottom. See photo of Nalgene bottle that has a tight yet easy to open top. Bottle has shown no deterioration by acetone in 2+ months of use.

[Chamfer]

Another way to mix without a mag stirrer is to make a 'tea bag' from cheesecloth (or similar), put the dry ingredient in it and suspend it in the solution (keep the lid on!). This will dissolve (best left overnight) in a thin stream and reduce the need for actual stirring of the mixture.

Yeah, but wouldn't it be a lot more fun to have a mag stirrer??

It's all about the toys.

[Chamfer]

I too used and liked Metallic's posted recipe. Use .525 teaspoon, (a slightly heaping 1/2 teaspoon), of Butvar 76 with 2oz/60ml of acetone in a 2oz/60ml Nalgene drop dispenser bottle.

With a 2 oz container, how are you applying the solution to fossils? Dripping or brushing on? In the few batches I've done I've just been submerging the samples. I'm dealing with small pieces (generally under 2") so this works well, but obviously isn't practical for a T-rex femur.

[DPS Ammonite]

Chamfer,

I apply the solution drop by drop on pieces up to 5" by 5". I sometimes selectively spot treat a fragile fossil on a larger rock so that I can then clean the untreated areas with less worry that the fossil with be destroyed. After the whole rock is cleaned, I cover the whole rock with the Butvar solution to give the whole rock a uniform look.

I believe that Nalgene makes similar bottles up to 8oz.that might be appropriate for larger jobs.

[tooth_claw]

Yeah, but wouldn't it be a lot more fun to have a mag stirrer??

It's all about the toys.

Ha! Agreed 100%!

I LOVE the opportunity to try out a new toy if I can.