Acryloid B-67 vs. B-72

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    • #132129

      I recently made the mistake of ordering only Acryloid B-72. What are the differences between the fluids? I would like to be able to mark objects as normal, but do not want to damage an item using the wrong fluid. Can I use them both the same way. Gaylord gives some specifics on their differences, but I thought I would ask the experts.

      Thank you!

      Liz

    • #132134
      Carrie Eaton
      Member

      Hi Liz, You can absolutely use B-72 in a marking kit. Do you have the beads or the pre-mixed solution? Depending on the concentration, it also makes a really good adhesive, a component in gap filler, and can serve as a consolidant or varnish. Here’s one of the best resources I know of on uses of B-72, written by Amy Davidson (AMNH) and Greg Brown (U. Nebraska State Museum). This paper even covers some different mixing recipes (depending on usage) and great methods of dispensing your solutions. I attached the pdf as well. Hope this helps:

      http://www.academia.edu/1237393/Paraloid_B-72_Practical_Tips_for_the_Vertebrate_Fossil_Preparator

    • #132133

      Acryloid or Paraloid B72 is a copolymer of ethyl methacrylate and methyl acrylate and is extremely stable. It is usually used for marking dissolved in acetone.

      Acryloid or Paraloid B67 is isobutyl methacrylate and is not quite as stable as B72. When used for markign objects it is usually used dissolved in white spirit so that it can be applied as a coating without disturbing the underlying number on the B72 application.

      It would be better (for the longevity of the number) to use B72 for the base and top coats if possible.

      Hope this helps.

    • #132132
      L. James Hansmann
      Participant

      Just a quick note to add to the discussion.  Acryloid/Paraloid B-67 will yellow slightly over time which is one reason I seldom use it.  The B-72 is very easy to work with, I have the premixed solution from Gaylord.  It is not, however, recommended for use on painted items.

    • #132131

      Thanks to all for the great and comforting advice/resources! I bought the premixed solution, but it’s good to know that depending on the concentration it has other uses.

      Thanks again!

    • #132130

      I use B-72 more than B-67 due to the yellowing mentioned above. The exception is plastic artifacts. The premixed B-72 acryloid can only be removed with acetone which would damage items made of plastic or old rubber. If I have items made of these materials I use B-67 just in case the label/number ever needs to be reversed.

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