All of these filter are available as either un-tared or tared.
We have pre-weighed filter media ready for
shipping today.
All of these items can be ordered pre-weighed to any
published method.
We also offer pre-weighed beakers and post
weighing services.
Technical Notes.
The method calls for
the filter to be used "coarse side up." The new 934-AH
filters look pretty much the same on both sides.What side
is up?
The Whatman glass microfiber filters (except for the Multigrade
150) are bi-directional and can be placed in a filter holder
with either side facing up or down. Older lots of 934-AH
paper, which were manufactured in a different location
and on a different
paper-making machine, did show different surface textures
on each side, but they too, were bi-directional. The test
protocol
should not have specified that the filter be used with a
particular side up.
What is the best way to mark filters for identification
purposes?
This depends on the intended filter use.
All marking materials add substance to the filter. Some inks
contain
metals and organics. It is recommended that the marking method
be specified after considering all the possible analysis
that may be performed on the filter and filtrate. If it is
not possible
to limit the possible analysis options consider making very
small notches on the outer edge before taring filters. In
all cases we recommend marking the petri dish with a complete
description of the filter including the filter ID.
