Hello, this is my first response to a Histonet discussion - what an
excellent method to communicate - I do not believe I have seen anything
like it. However, as I am unfamiliar with it, I am not sure that this will
reach the Histonet.
We do research and provide microwave heating and processing devices for
laboratories and light industrial applications including research tissue
processors and other microwaves for staining, etc...
Microwaves are great time savers as the energy adsorbs into the material
being heated differently that the way conventional heating does. They can
be quite consistent as well once people understand how to use them and how
they operate. Looking for hot spots with a bulb array is not a great
method for finding hot spots as Rene J. pointed out. She accurately also
pointed out that the hot spot will change with a load in it. By the way,
if you can control power well, you do not need a separate water load. But
the introduction of any material in the microwave cavity will certainly
change the energy distribution pattern and thus the so called hot spot.
Consistency is important to consistent processing. Factors that affect
Line voltage - always use a microwave oven that compensates for line
voltage changes. Most do.
Load - do not use a 50 ml sample and think you will get the same results
with a 500 ml sample. Nor will 10 - 50 ml samples vs. a 500 ml sample as
the samples will be in different locations within the cavity and thus
change the energy density.
Starting temperature of the sample will make differences in results
Location in the microwave will change results. Mark with a marker a
location and always use it.
I have heard of other methods to get consistent results as I am sure you have.
Here is one that I have never heard with regard to histoprocessing. The
temperature of the magnetron and the power supply transformer (major
microwave generator components) makes just about the biggest single
differences (can be over 10% variations) in process consistency. The
heating of the magnetron is quick, in about 3 minutes of operation, but the
transformer can take 15 minutes or more as it is a large thermal mass.
One way to reduce the variation is to operate the microwave with a liter or
two of water on full power for 20-30 minutes to pre-warm the microwave.
The other way is to use a microwave that uses the temperature of the sample
to control the process.
We are not biologist but are microwave engineers and understand the
operation of microwaves and how they heat. Hope this makes sense to all of
Caution - If I understand it correctly, you are using the microwave to heat
the HIER solution to boiling and then putting it into the steamer. This
would greatly decrease the initial heating time. Be very careful as it is
possible to superheat, but not boil liquids in a microwave and then have it
vigorously boil explosively when the liquid is move or stirred causing
Tips to prevent:
Do not use a container with a small mouth!
Stir the solution every couple of minutes.
Leave the solution in the container undisterbed for a period of time before
Protect you face and body (arms and hands also) with face shields nad
Microwave Research and
8685 Cherry Lane
Laurel, MD 20707
Direct email: firstname.lastname@example.org
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