SPI Supplies® Brand Embedding Resins
Some comments about minimizing and/or eliminating exposure to dust caused by
sawing of the cured block
The typical situation:
More often than not, there is the need to "shape" the block which means cutting it
down to right size and shape for the ultramicrotome prior to thin sectioning. The
long time approach and one that has been used over the years going back to a day
when we did not appreciate as we do today, the hazards of inhaling the "dust",
users of such resins typically used a small clamp-on or
vacuum based vice and a small jeweler's saw.
Quite a bit of dust would get generated, and it was that many years ago that
this operation was done out in the open, without much regard to the consequences
of such dust inhalation. We are all more knowledgeable about the potential consequences
of inhaling such dust, and therefore, any sawing, grinding, or other wise milling of the
block in a way that would generate dust and air borne particulates should be done under
a well operating fume (exhaust) hood.
A better approach:
Think about ways to minimize the need for cutting by always seeking out the the
embedding mold size that is most appropriate for the job at hand. This will minimize
the need for cutting the resin in the first place and is the first place to start with a
dust minimization program. Another piece of good laboratory procedure is to make sure
that the specimen of interest is as close as possible to the tip. What ever trimming
is then necessary quite probably could be done with a fresh
razor blade or glass knife on the microtome.
Ideally with such practices, the need to saw at all might be eliminated completely.
If sawing is actually necessary:
If sawing is necessary, we would recommend it be done only in a well operating chemical
fume hood, using a vacuum base vice as previously described. We would recommend
surrounding the vise with wet lint free cotton wipers
so that when the job is finished, the vice can be lifted away, and the wet wipers used to
clean up all remaining dry dust.
The next thing to consider is the disposal of this wet powder. It can not just be
disposed of in a waste basket because once dry, and when the basket is emptied, the dry
dust could again present an inhalation risk to the one emptying the waste basket. One
way to deal with this is to let the lint free wiper dry out and then essentially soak
it in 5 Minute Epoxy resulting in a
hardened inert mass that could be disposed of as an inert substance (and following all
local and federal regulations in effect). However that might be seen as overkill by some.
Another possibility would be to put the wet wiper and dust in a plastic or other type of
container that can be tightly closed and then disposed of as a hazardous waste following
standard institutional procedures.
Another Unforeseen Danger: Vacuuming
If you might think about using a vacuum cleaner of any type to clean up the dust, while
it indeed would pick up and hold (in the filter bag) the larger particles, the smaller
ones, and those unfortunately that would be the respirable range, would just pass through
the bag and be exhausted back into the room, creating an even worse inhalation hazard
than the one that was supposedly being eliminated! So cosmetically at least the mess is
cleaned up, chips and chard of resin have been captured by the vacuum cleaner, but from
an inhalation stand point, those are not the ones that are of concern.
We realize we don't necessarily have all the answers and should anyone reading this
cautionary note have any further comments to add or questions, please don't be bashful,
please pose them to us.
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Tuesday January 06, 2009
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