Reply To: Case Miller's Original Post

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Matthew Speights

@robertross @jkallmeyer and @rleder, I apologize for taking so long to get back to this thread. I mostly put aside fossil activities for several months (with a few collecting trips that I just had to take…) to build a New Guinea biotope paludarium for my wife. Now that my living room is a jungle, I’m getting back into paleontology.

Back in the Spring, I started trying to track down a replacement for “Rock Quat” or “Quaternary O.” It appeared that a good replacement that was manufactured recently would be Rewoquat W 3690 PG, the specific formula used in this paper on microfossil extraction. After many emails and tracking down the company (Evonik) and manager, I finally got to the right person, who was so kind as to send me a sample. It turns out that, although Rewoquat W 3690 PG is only distributed in Germany, a similar formula with a different name and higher concentration (90% instead of 75%) is available in the USA, Varisoft 3690 PG.

I received a one pint sample of Varisoft 3690 PG, and although I haven’t had time to run many tests, I did place several trilobites in it for several weeks. It was quite viscous (only a little less so than petroleum jelly), so I diluted it with ethanol (190-proof Everclear…”No, it’s actually for fossils.” 🙂 ). As you can see from the attached image of four Flexicalymene retrorsa minuens, it worked very well to disaggregate the shale around them. After removing them from the solution, I rinsed them with hot water and brushed them a little to remove the solution and any residual shale. If you really wanted to speed up the process, perhaps you could boil them like they used to with Quat-O and a lab hot plate at University of Cincinnati. Disclaimer: I would definitely read the safety data before heating this stuff up! Also, Jack told me that once someone forgot the boiling trilobite, and came back to a trilobite permanently encased in tar (Ordovician meets Rancho la Brea!).

A few caveats. First, I wouldn’t try Varisoft on anything but enrolled trilobites or fossils on top of limestone, because I find that with prone trilobites it will eat away at the shale that holds the trilobite together. As the paper I linked to noted, “However, matrix-supported fossils such as trilobites may fall apart upon rock disintegration in Rewoquat; we recommend that in such cases Rewoquat should be used to clean them on a rock bedding plane.” Perhaps test on a not-so-unique fossil first. Jack has a lot of experience with similar chemicals, so any additional recommendations would be great.

Second, the MSDS for the product indicates that there are definitely appropriate safety measures to take, and that it is very toxic to aquatic organisms. So, please follow appropriate safety precautions (check out page two of this link and the manufacturer’s documentation) and dispose of it properly. Incidentally, you should be able to drain off and reuse Varisoft for a long time. The only amount you lose will be whatever clings to the fossils and is washed off when you rinse them. The way surfactants like Varisoft work, they’re not exactly reacting with the clay, but rather causing the clay to disassociate (those with more chemical training, feel free to correct my terminology), so the Varisoft stays usable. Do NOT pour it out or throw it away when you’re done, or you’ll be throwing away perfectly good chemicals.

So, how to get it? I explained to the manager who sent me a sample that I wanted it for testing with fossils, and that other paleontologists might be interested. I asked whether it would be okay for others to request samples as well, and she said it would not be an issue to get more samples. The only restriction is that they cannot ship to a non-commercial address. I couldn’t have it sent to my home address, but since my wife Christa works in the physics and geology department at Norther Kentucky University, I was able to have it sent to the geology lab there. Jack had trouble in the past with trying to get chemicals shipped and was told that a university did not qualify as a commercial outfit, but I didn’t have any trouble this time. As of yet, I have not been able to get a clear answer about ordering larger quantities, but the sample is a pint, and a little Varisoft goes a long way. If more of you try it out, and are interested in ordering larger quantities (group buy?), then I would ask again. I have the contact information for the manager who can send samples, but I don’t really think it would be fair to her for it to be circulating on the internet for all to see. So, if you would like to request a sample, send me a message, and I’ll send you her contact information. If I have the time, I’ll try to send her a little “introductory” email letting her know that another paleontologist will be requesting a sample as well, so it’s not out of the blue. I’ll also send you a PDF with some safety information about Varisoft.

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