"How absorbent is the honey of pesticides from old, black, dark comb ...."

The simple answer is not very.  The reason is that all chemicals will distribute between a non polar solvent like wax and a polar solvent like water or honey.  The majority of pesticides love non polar solvents and hate polar solvents.  So, they will tend strongly to stay in the wax and not move into honey.  But a few pesticides do love polar solvents.  For instance Roundup and neonics.  They would very rapidly move into honey if the wax was contaminated.  You asked specifically about old dark comb.  The only way you get old dark comb is to raise brood in it.  Comb that is many years old but never had anything but honey in it will not turn dark.  All of that brood that resulted in dark comb also resulted in extraction of any pesticide contamination that was the kind that liked to be in a polar solvent simply because brood and brood food are polar solvents.  So, in the process of rearing brood you self clean the old comb of any pesticide that is water loving like Roundup or neonics and later when the bees put honey in that comb there is no polar loving pesticide left to extract.

The pesticides that love a non polar solvent may well be in the wax.  There are lots of analyses on old wax that show that bee keeper applied pesticides persist in wax for many years.  Now, if they persist in wax for many years they simply can not be very easy to extract or prior years brood raising or honey production would have removed them.

From a honey contamination point of view I do not see why 25 year old comb that has had brood raised in it would contaminate the honey any more than foundation that was drawn this spring, used to raise brood until August and then used for extracting the fall honey crop this year.  Nor do I see any reason why comb that has been used to raise brood would provide more contaminated honey than comb that has never had brood in it.  There may, or may not, be good reasons to rotate out old comb to prevent virus or bacterial disease build up.  There seems to be some decent data to argue either side of the disease issue.  Obviously for AFB getting rid of all comb regardless of prior use is important.

Old black comb, by the way, contains very little wax.  As an experiment last fall I cleaned the comb off 30 deep old black brood frames equipped with plastic foundation.  I rendered the wax.  I got about two ounces of wax out of those 30 frames.  I extracted a sample of the slum gum with kerosene, which is an excellent wax solvent, and showed there was very little wax lost in the sludge.   Mostly that old black comb is cocoons and propolis.

Dick

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