Removing Tape Residue From Grain Mounts Without Damaging the Epoxy

[DCoulthardJr]

Hey all! Looking for some advice here. I have a grain mount with a substantial amount of bubbles surrounding the grains at the bottom of the mount. Peeling the double-sided tape off removes the plastic part of the tape but the adhesive on the sample side stayed on the epoxy round. I thought to remove the adhesive using a moderate grit SiC sandpaper (600-400) and ground the mount down until I realized that I'd intersected the crystals, but there is still a membrane of tape adhesive over all of the bubbles. It must have been pushed into the bubbles during the grind. Do any of you know of a way to remove this adhesive using a solvent without damaging the epoxy? We use Buehler EpoThin and the corresponding hardener. Also, is there a double-sided tape out there that I should look at using to mitigate this in the future? Of course, eliminating the bubbles in the first place would be ideal.

[crystalgrower]

BUBBLES:

Are you preheating your mount before adding the epoxy?  You should set up a PTFE block on a hotplate whose temperature can be well controlled to 50C and preheat the mount.  Use one of those infrared detectors sold at hardware stores, they are a very good investment.

Mixing the Epo-thin by SLOWLY rocking the correct proportions in a disposable tube would also help prevent bubbles.

Add the mix to the preheated mount dropwise from an edge where there are no grains.  The epoxy should flow quickly across the surface as soon as it warms up.  Keep adding small amounts offside until all grains are covered by at least 3mm of epoxy. 

TAPE:

You can safely use isoppropanol and isopentane (NEVER acetone) on fully hardened Epo-thin depending on whether the tape residue is polar or nonpolar.  Neither solvent will dissolve ionic salts during a brief exposure.

I would have started with 1200 grit alumina paper to prevent damage.  It's slower but safer.

OTHER:

Hardware stores in Caanda sell aluminum-metal sticky tape (high temperature tape) that has the sticky side protected by paper.  This tape can be smoothed perfectly flat before adding the retaining ring for a mount.  The retaining ring should be hand polished "flat" to at least 1200 grit before putting that face down onto the tape.

If you find any of this to be useful, please add the details to your lab's procedures.   

[crystalgrower]

I was thinking of another Buehler product when I wrote the above.  Try EpoHeat if your fine grained material is heat stable.  The viscosity drops to nil at the point of cure and fills bubbles well.