Sediment grain SEM mounts

Thanks to Dr. Lindsay Szramek for her help with this process.

Equipment needed

Your sediment samples, dried and appropriately labeled
Lab balance
Hot plate (ideally in a fume hood)
Epoxy (we use SpeciFix resin with SpeciFix-20 curing agent)
Metal sample tubes (see below)
Glass slides, large if available
Aluminum foil
Double-sided tape
Sharpie
Weigh paper
Aluminum weighing dishes
Calculator
Disposable pipets
Popsicle sticks (toothpicks can also work)

If you need to make sample holders:

Copper tube
Small pipe cutter
Fine sandpaper
Glass plate or other flat hard surface
Engraving tool

Make metal sample tubes, if you don't have enough:
1. Cut copper tube into short sections
2. The pipe cutter leaves an angled edge on the tube. We need to get rid of this so that the tube will sit flat on the double-sided tape later on. Put your glass plate on a work surface and place your sandpaper grit-up onto the glass plate to provide a flat grinding surface. Carefully deburr and flatten one cut side of the copper tube until it is flat and reasonably smooth. (On the other cut side, you only need to round it so that you won't cut yourself.)
3. Use the engraver to inscribe a unique identifier on the copper tube. It should be readable with the sanded side down. A, B, C, etc. is good, or you can inscribe your sample numbers if they fit.
Establish your mise en place (get everything ready)
1. Put aluminum foil on your hot plate to protect it from spills and turn on to a low-ish temperature - no higher than 80 degrees C or so.
2. Put weigh paper on your balance to protect it from spills
3. Prepare your slide:
  1. Clean the slide so that it is flat and the tape will stick. Stick double-sided tape down to cover the surface.
  2. Put the sample tubes, smooth side down, onto the sticky tape, and push down on each to make sure they are stuck. You can stick multiple sample tubes onto one slide.
  3. Using the sharpie, label which sample should go in which sample tubes by writing the sample number directly on the glass slide or sticky tape.
  4. In a lab book, write down which sample will go in which container. You don't want to lose track of this!
4. Carefully add sample to sample tubes:
  1. Crease a new sheet of weigh paper.
  2. Pour a small amount of sample onto the weigh paper, then fold the weigh paper and carefully pour into the appropriate tube. There should be enough sample to cover the bottom of the tube, but you don't need more than that. Discard the weigh paper when done. NOTE: avoid contamination! Don't let any sample get in other tubes!
  3. Pick up the slide and tap until the grains appear to be adhering to the exposed tape at the bottom of the tube.
  4. Repeat for the other sample tubes.
5. Put your samples near the hot plate.
Mix the epoxy
1. Tare out an aluminum weigh boat on the balance.
2. For Specifix-20, we use 7 parts resin by mass with 1 part curing agent. Add the resin first, from the squeeze bottle directly to the weigh boat. It is easiest to measure 7 grams (If you need a different amount of epoxy, you may need the calculator to get the proportions right).
3. Add 1 gram of curing agent using a disposable pipet (or see above). Discard the pipet when finished.
4. Put the aluminum boat on the hot plate. Using a popsicle stick, mix the epoxy with a toothpick or posicle stick for about three minutes, until it is thoroughly and completely mixed.
Fill samples
1. Put the sample tubes next to the epoxy boat on the hot plate.
2. Add epoxy to the samples, one at a time, by holding the popsicle stick over each sample tube and allowing epoxy to drip into the sample tube. The tubes don't have to be full, but epoxy must completely fill the bottom where the sediment grains are.
3. Turn off the hot plate and either leave the samples on the hot plate or in a safe place overnight, for more than 8 hours.

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