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Large Volume of 5% Butvar Solution - rushed mixing process = congealed clumps


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fossilstacey

Hi Fossil Forum,

I joined this forum for help with an issue that is baffling me, I have used butvar for many years. I make multiple liters at a time and usually slowly mix the butvar in over the course of 24-72 hours to prevent clumping. This is a standard 5% solution, 50g to 1000mL. 

 

I was in a rush, and I basically dumped all the powder into the solvent at once. After a couple days and stirring often, the solution seemed stable and the clumps were gone. We then filtered it into smaller bottles then, after a few days the resin congealed, almost to like a jello looking consistency in some of the bottles. I realize I should have stuck to the original method, but I am trying to rule out other possible reasons for this reaction. 

 

Has anyone else had a similar outcome of mixing butvar too fast, I realize many of you only mix small amounts at a time. 

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DPS Ammonite

What kind of solvent are you using? Are your bottles that you put the solution into tight and in good shape? Could the solvent have leaked out in some of the bottles? You mentioned that the jelling occurred in only some of the bottles, correct? Could the solvent have reacted with and partly dissolved the bottles? What are they made of? Did you put them into new bottles or ones that you had made the Butvar solution in before? Could they have had contaminants in them such as water or oil? 
 

Could the batch not have been mixed well where the latter pours had a higher concentration of Butvar?
 

In other words, are there any differences between the bottles that gelled and those that did not?

Edited by DPS Ammonite
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Ptychodus04

If the bottles are ones of a type you’ve used previously, IMHO the most likely culprit is insufficient time for proper dissolution of the resin. Since Butvar is a powder, it will look dissolved before it actually is. I’d be willing to bet you got some transparent clumps of partially dissolved resin in the bottles that gelled. Once it finally dissolved, you got a much higher concentration than you were going for while the other containers have a lower concentration.

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fossilstacey
Posted (edited)

@Ptychodus04 - you are 100% right I bet, the solvent is a blend of toluene/acetone. The bottles aren't the culprit, we have ldpe and phenolic resin lined aluminum bottles. The whole process being rushed ended in a nightmare of a result, after using butvar for 5 years this is the first time I rushed the process and the first time I ended up with this result. 

 

Rushing never ends up well in my experience. I will report back after we mix the next batch. 

 

Thank everyone for the feedback. 

 

 

Edited by fossilstacey
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Ptychodus04
1 hour ago, fossilstacey said:

@Ptychodus04 - you are 100% right I bet, the solvent is a blend of toluene/acetone. The bottles aren't the culprit, we have ldpe and phenolic resin lined aluminum bottles. The whole process being rushed ended in a nightmare of a result, after using butvar for 5 years this is the first time I rushed the process and the first time I ended up with this result. 

 

Rushing never ends up well in my experience. I will report back after we mix the next batch. 

 

Thank everyone for the feedback. 

 

 

 

You can most likely save the batch in question (although it might be more work than it's worth) by combining the various viscosities into a larger container and regularly agitating it. The solutions should normalize in a couple of days. You will have a slightly inaccurate solution but I'm assuming you're using this for fossil stabilization and not some technical use so, precise mix isn't critical.

 

I'm interested in the addition of toluene to the solution. What benefits does it provide over straight acetone?

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