BUTVAR B-72 - Is it the same as PARALOID B-72 & BUTVAR B-76?

[kenoakee]

  Its been a minute since I've posted

 

   About 20 years ago while doing research online for fossil preservation I read somewhere that curators used "B-72" as adhesive and consolidate. so I did some digging and found a supplier that offered up free samples. I ordered some and after it arrived we were moving and it was packed away. the next couple of places I lived didn't afford me the space to do my hobbies and prep my fossils. Much time has passed and I am now able to haul out some of those fossils and work on them. I dug out the "B-72" I had ordered years before and started to look up info on how to properly mix my "B-72". Low and behold I didn't realize that there are other products that use the same handle "B-72". I now see its "Paraloid B-72" or "Butvar B-76" that are most commonly used for this purpose.

 

   So what's the difference?, and can this "Butvar B-72" be used? Is there or could there be any negative or undesirable effects from this stuff? will it ruin my fossils?

 

  If it can be used, does one dilute it the same as the other products? what W/V % should be mixed for consolidating vs using as an adhesive?

 

Thanks for any input

 

Edited July 20, 2023 by kenoakee
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[Ptychodus04]

The number difference is in the specific formulation of the plastic. Both Paraloid and Butvar have different formulations designated by the different numbers.

 

Here’s a link to a technical comparison of Butvar resins: LINK

 

There are some significant differences between B76 and B72. 
 

If it were my decision, I would likely follow the accepted use history of B76 in paleontological applications. There’s a reason the industry uses B76 and none of the other formulas.

[CDiggs]

"It is not enough to list B72, B76, or B15 as the adhesive used.  B-72 could refer to Paraloid B-72, which is commonly used on fossils or Butvar B72 which is rarely used.  Butvar B76 is actually a mix of three different polymers which are also used in Butvar B98 but the ratios are different in each."

 

http://preparation.paleo.amnh.org/49/names

 

I would have assumed Butvar B-72 was the same as Paraloid B-72, but it looks like I would have been wrong. I don't know why Butvar B-72 is rarely used on fossils, but that phrase alone would cause me to hesitate before using it.

[hadrosauridae]

The different chemical variations have unique properties including clarity, strength, glass temperature, shine and solubility.  Using a different formula without knowing exactly how its different isnt a wise choice.  Some times it could a case of "whatever you have available" when in foreign countries or just far from home, but those instances are typically followed up in the lab with removal and application of the accepted form.