Greetings
I sent out a posting last night that has crossed with Judy's.
>Jeff has added nicely to the sum total of human knowledge with list
>above. Now if only he or Terry will tell us hygrometer(hydrometer?)less
>persons, what and where you get one, we can make our own lists.
I bought my heavy liquids hydrometer for work with ferric chloride where it is
essential to establish the specific gravity of the etchant in photogravure.
(There may still be a place on the Kentish Town workshop from 22-28 July). It
is nothing more than a glass tube with lead shot at the bottom so that it will
float in a heavy liquid at different levels to indicate the the specific gravity
of the liquid which is marked offf on the side of the tube.. I also have a
hydrometer to measure the specific gravity of home made beer but that one has no
lead shot as it is intended to measure the SG of liquids very close to '1' ie
where one ml of water weighs 1 g. I bought the heavy liquids (Baume) hydrometer
from Hunter Penrose who also supply Le Page's fish glue. I use the tall thin jar
for measuring the SG of beer as I do not make beer any more. The jar, which
looks like a small spaghetti jar, holds 250 ml. Humidity and temperature
certainly affect the SG but I would not have thought that small variations would
have been critical for gum. Suppliers to the printing industry should be able to
supply the Baume hydrometer which is probably difficult to ship. But if anyone
needs hydrometers or fish glue or ferric chloride or ammonium dichromate or
Stouffer step wedges they can all be got from Hunter Penrose, 32 Southwark
Street, London SE 1 1TU on 0171 407 5051.
It is better to walk to get there as it is on that weird one way system round
Southwark. Coming south from London Bridge down Borough High Street take the
right fork by the Hop Exchange and you will find Hunter Penrose on the right
under the first railway bridge. Burt's Paper ( for Fabriano and the Wells
papers), Intaglio and Silverprint are all within five minutes walk of each
other.
>It does occur to me to wonder if the hydr/hygrometer is calibrated along
>some absolute scale, because I suspect discrepancies between instruments,
>or by elevation, or air pressure, or whatever, not to mention latitude &
>longitude. How accurate is it? How much liquid do you need to float it?
See above
>And Jeff, thank you from the bottom of my heart for sharing my -- let's
>call it skepticism -- about gloy... (heh heh).
As my wife says, ' Somebody is making the tea with cold water'.
Terry King
Judy