Re the present threads on burr comb on excluders and cleaning or not
cleaning extracting equipment.   
Although the amount of burr comb varies from stock to stock, most of it is
due to incorrect spacing.  The space which the bees will respect has been 
known since the days of Langstroth and well made hives allow approximately
one quarter of an inch between top bars and the wire of the excluder and
another quarter inch between wire and the bottom bars of the super.  If
these gaps are too big or too small then you will get excessive burr comb.  
The same gap is necessary between supers.  Frames are made to be a quarter
inch less deep than the box they are in and that space can be either top or
bottom.  Generally it is at the top.  Clearly mixing the two arrangements 
will result in no gap or a double gap with consequent glueing up or burr
comb.  I have seen excluders which have no frame, frame on both sides and 
frame on one side.  Only the last one is suitable for a properly designed 
hive.
Scraping an excluder to clean it is rather risky.  I would suggest having a
solar extractor big enough to take excluders.  If you keep one or two
excluders spare as replacements a day in the solar will clean it perfectly.
 Moreover it will sterilise it also ready for it to go on another hive.
Mentioning sterilising leads me to another comment.  I am surprised at the
number of letter writers who appear to feed honey from one stock back to
others.  Disease (AFB, EFB, Chalk, Nosema, etc) is always lurking just down
the road.  Few beekeepers can discover it in its early stages and feeding 
honey indiscriminately is a sure way to spread it.
With regard to leaving extracting equipment honey covered over a period it
would be very unwise in my part of the world and yours too unless the
atmosphere is very dry.  Here, winter and summer, the relative humidity is
such that exposed honey will take in water.  Air- born yeasts,always
present, will set up fermentation, hardly desirable for the next batch of 
extracting.  Honey is acidic, fermentation will increase the acidity.  
Unless all your equipment is stainless steel or food grade plastic this
could cause a reaction.
Incidentally, I see that hot water is recommended for cleaning.  Cold or
warm water yes, hot no.  It will melt any wax and propolis present, which 
will then be almost impossible to remove.                       Regards    
Sid P.