Thin Section Lab
Susan Boehm
Summary
un·re·mit·ting
/¿¿nr¿'midiNG/
adjective: unremitting
never relaxing or slackening; incessant.
- 50 Thin section requests with a variety of material: carbonate, mudstone, calcite, basalt, highly altered basalt.
LP-50
One jig seems uneven and produces uneven slides. Variability on micrometer scale as I spin it around- swings between 5 tick marks on the large face scale. Slides frosted on the second jig come out very even so I only used the one after I noticed. This picture is the same jig and same scale just with the jig rotated.
When the abrasive drum spins there is leaking around the spout connection. Before assembling it for the next expedition, I recommend using a better o-ring.
Petrothin
Replaced battery in micrometer.
The only time I had a problem getting a good vacuum was when the slide I was using was oddly uneven and did not sit flat on the chuck face. All other slides worked fine so I think it was just a fluke of a bad slide. I smeared 111 Compound on the back of the slide in order to get a decent vacuum to cut the billet and tried to wipe it all off after.
Some water gets in the VS2 but I drained it and left the plug open for it to dry out after every use. I think it depends on the slides themselves because sometimes no water gets in at all and other times it does. No need to replace blade or cutting wheel.
PM5 Polisher
Worked well with no problems. Refilled the abrasive jug with another vial of diamond powder and glycol. Did not need to replace the polishing pad.
One of the sample holders I was using left scratch marks on the backs of the slides. I stopped using it and used a different one. We may want to order a new set (6) in the future if there is an expedition with heavier usage.
Samples and methods
Received new Kemet impregnation vacuum chamber. Used for surface and full impregnations. It achieves a stronger and more consistent vacuum than our homemade vacuum bell jars. I would leave some samples in for 30-40 minutes and the epoxy was still liquid enough for me to work with.
Polishing works way better if you smooth samples down on a glass plate with 1000 grit first. Do this for about 5-10 microns. I get the thin sections down to 40-50 microns using 600 grit, then a little bit more using 1000, then finally the PM5 polisher. The slides look so much smoother and more reflective and makes a big difference. One scientist remarked that the polish looked much better.
https://www.lakeheadu.ca/sites/default/files/uploads/3143/geoprep.pdf
https://www.nrc.gov/docs/ML0037/ML003750080.pdf
https://www.hou.usra.edu/meetings/metsoc2017/eposter/6304.pdf
Miscellaneous
Everything is too tall. If only the counters were lower….or the floor was higher.
New Epotek Epoxy should be arriving before Expedtion 378 because now all containers are expired. The cleaned out and refurbished pumps worked great and I think kept the epoxy fresher and more useable throughout the expedition so I didn't have to use disposable pipettes. I recommend thoroughly cleaning out the dispensers every expedition to prevent any crystallization.
I created an end of expedition survey to be given to scientists to evaluate the quality of the thin sections so that improvements can be made if necessary. It can be found on the TS lab desktop computer in Thin Section folder, and on confluence (Thin Section Laboratory Notebook > Resources > General)
Also on confluence is a list of questions/concerns for any tech who goes to Logitech training and can get advice.
Some slides get small cracks and chips on the edges after frosting on the LP50, how can this be avoided?
Display screen on the LP50 is very dim, can that be fixed?
What types of different grits/abrasives and fluids can be used in the abrasive drums on the LP50 and the PM5? Any suggestions for softer or different types of material?
Do we need new slide holders for the PM5 or can they be repaired? Some are leaving scratch marks on the backs of slides.
Any different types of the epoxy to try? Ones with longer curing time? Thinner and easier to absorb into soft material? Any other tips on impregnation?
One jig is uneven, review procedure on how to flatten the chuck face.