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JohnBrewer

Paraloid B-72 Practical Tips

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Ptychodus04

That's a great paper. Thanks for sharing @JohnBrewer

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Pixpaleosky

Excellent paper, thank you very much !

 

Which concentration should be used to consolidate bones ? And to glue fragments ?

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Mark Kmiecik
5 hours ago, Pixpaleosky said:

Excellent paper, thank you very much !

 

Which concentration should be used to consolidate bones ? And to glue fragments ?

These questions are answered in the paper. That's why John posted it here. It takes about two hours to read if you go slow so you can understand it. There is too much variation among the different specimens and type of fragmentation. The question you asked would take nearly as long to explain for each variation as reading the paper since there are so many different ratios and combinations of other chemicals than can be used in addition, as well as methods to make the adhesive take on certain properties to match the situation at hand, so just read the paper. You should copy it to your computer as a reference if you will be doing a lot of prep, or remember how to find it here. 

 

Simply stated, there are at least two dozen answers to your question, unless you can say exactly which specimen you are working on. For instance, ratios of solution from 1:2 to 1:100 can be used for consolidation. Which will work for your specimen? I don't know. What specimen are you working on? Once we establish that we can discuss what might work best and experiment a bit with that specimen to check what gives the best results. That in itself might be a month's worth of work. Experience (also known as trial and error) would cut that amount of time by at least 50%, but without the experience we would have to put in the time.

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Pixpaleosky

I read most of the paper but I wanted to have feedback from people doing it. I uee a 5% ratio and i feel it is not enough. As you say i will discover by myself then.

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Mark Kmiecik
21 hours ago, Pixpaleosky said:

I read most of the paper but I wanted to have feedback from people doing it. I uee a 5% ratio and i feel it is not enough. As you say i will discover by myself then.

It's tricky. There's a section in the paper that refers to ratios used to consolidate loose grains of sand, which would be the "thickest" concentration that would penetrate an extremely porous matrix/specimen. I suppose the "thinnest" that would be useful would be a 2% solution by weight in ethanol to consolidate Pennsylvanian fern-on-shale specimens where the purpose is to prevent peeling. But even this could be different on a specimen collected a mile down the road. The point is that it's a judgement call best made after experience is acquired. Testing and experimentation should be done unless it's the exact same thing as the last 20 you did, and even then it might be wrong.

 

I suppose what I'm trying to say is that it's a best-guess situation based on experience.

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Ptychodus04
21 hours ago, Pixpaleosky said:

I read most of the paper but I wanted to have feedback from people doing it. I uee a 5% ratio and i feel it is not enough. As you say i will discover by myself then.

I use a 2% solution for most consolidation applications. It is thin enough that it penetrates deeply yet thick enough to impart some support to fragile specimens.

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Pixpaleosky

@Mark Kmiecik

@Ptychodus04

 

thank you, i use it on a quite porous matrix, and diluted in acetone. It prevents from loosing grains of sand but not to consolidate deeply. Next time I will try different concentrations on pieces of matrix.

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Ptychodus04
4 hours ago, Pixpaleosky said:

 

 

 

thank you, i use it on a quite porous matrix, and diluted in acetone. It prevents from loosing grains of sand but not to consolidate deeply. Next time I will try different concentrations on pieces of matrix.

You will probably have to employ a couple  applications of the 2% solution to get significant consolidation of porous matrix.

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Mark Kmiecik

Ethanol is less volatile than acetone and will evaporate more slowly, so if you want to keep the same percentage, but deeper penetration use various ratios of ethanol to acetone. The longer it takes for the solvent to evaporate the deeper it will penetrate because it has more time to do so, and the less it will tend to draw the Paraloid out of the specimen as it does. You can also pre-wet the specimen with ehtanol to aid penetration and to reduce the amount of consolidant that is drawn towards the surface as the solvent evaporates.

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Pixpaleosky

thank you very much @Mark Kmiecik ! 

I will.keep you posted next time I use paraloid. :dinothumb:

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