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Note: At no point in this procedure is a safelight required.
Put the barium sulfate in a 21 oz. working glass set up for Oster
mixing. Set a small funnel in the small hole in the lid.
Start the mixer at lowest speed and slowly add the water through the
funnel. After the water is added, lift the lid enough to scrape
the inside of the glass. Reset the lid and give the baryta paste
another whiz. Remove the lid and whisk and scrape as much of the
paste as possible to the bottom of the glass. Reset the lid and
mixer.
Melt the gelatin in a waterbath to 45-50C.
Strain the melted gelatin through a stainless steel tea strainer into a clean
beaker and immediately add the melted gelatin slowly to the baryta paste in the same
manner you added the water to the dry barium sulfate. Again,
scrape down the sides and give another whiz. Remove the whisk and stir
in 5 ml Everclear with a clean plastic spoon. The mixture will be
very frothy. Strain it through a clean stainless steel tea
strainer into an 8oz canning jar or similar. You may have to help
the last of the mixture through with the back of a plastic spoon. Don't
worry about getting all the froth. Cover and refrigerate.
As soon as two hours later, or up to a week later:
Prepare the Rives paper for coating. (I usually
do this while the baryta-gelatin is setting up in the refrigerator.)
Cut the paper 14 x 20 inches (or work out your own best dimensions).
Have a number of sheets of thick (1/4")
plate glass (16 x 22 inches) ready with enough flat, level area to set
them aside as you coat each sheet. The area where you will be
drying the coated paper should be clean and the air should be as
dust-free as practical. Since I have a limited workspace, I
have built a cabinet for the glass sheets, along the same design as the
cabinet for my granite (here).
One at a time, dip the paper in warm distilled water
held in a tray larger than the paper. Leave the paper in the water
only long enough to evenly wet the paper through. Lift the paper,
allow it to drain a minute and then carefully lay it flat on a sheet of
glass. Gently scrape off the water and press the paper evenly
against the glass with an impeccably clean squeegee. The moisture
will hold the paper to the glass without tape. Cover the paper
with a piece of clean plastic wrap or mylar sheet so that it doesn't
start to dry before you can coat it with your baryta mixture.
Repeat with five more sheets. Since I don't like to waste paper, I
have another five sheets of glass and five more pieces of dry paper
ready to wet and squeegee, one at a time, as I need them to use up the
last of my baryta coating.
Set the covered jar of cold baryta-gelatin in a room temp waterbath
and slowly bring the temp up to 45C. The froth bubbles will be all but
gone by the time the gelatin melts. It is important from this
point on to handle the mixture gently so as to avoid introducing new
air. When the waterbath hits 45C, uncover the gelatin,
insert a thermometer and gently stir once or twice with a clean plastic
spoon. Add 5 ml Everclear and stir slowly and gently for a
couple of minutes until the Everclear seems thoroughly mixed in. When the
gelatin temp hits 42-43C, gently stir in 15 drops glycerin. After
this has been thoroughly worked in, add 5 ml Everclear and stir
a couple of minutes. Strain through a gold mesh coffee filter
into a clean beaker. Check the temperature of the mix. When it
drops to 37-38C, add 12 drops glyoxal and stir a couple of
minutes. The baryta is ready for coating. During coating,
keep the baryta in a 36-38C waterbath. I make my first
sheet on the small side to check the consistency of the mix. If the
first coating looks like it has bubbles, add a little more Everclear.
A full size sheet of paper will use about 20-25 ml of coating.
I have had good luck with 7 wraps of mylar (3M #850) tape on the
puddle pusher, but I recommend your own trials to determine what's best
for you.
About an hour after you have finished coating all the sheets,
lift them off the glass and hang them to finish drying. I have a
folding clothes drying rack that I set up in my darkroom.
Clothespin the sheets by their corners to a rod on the drying rack and
then attach two more clothespins at the bottom. If you don't
weight the bottom, the paper will dry in a tight curl.
After the paper is thoroughly dry, take the sheets down and one at a
time, tape a sheet, by all four corners, to a clean, dry sheet of glass.
With a very soft, clean, lint-free cloth, gently but firmly and
thoroughly buff the surface of the paper. This produces a lovely,
smooth, semi-gloss surface. If you can do this outside and wear a
dust mask, it would probably be smart. There aren't a bunch of
cautions involved with barytes, but you will be making an aerosol dust,
which is never smart to breathe or let settle around.
To coat the baryta paper with emulsion, repeat the wet and squeegee
steps and wet-coat with emulsion made for wet-coating (i.e. less water).
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