on 29/11/01 12:14 pm, Joao Ribeiro at jribe...@greco.com.br wrote:
Hi Alexis,
Paraffin oils have a boiling point in the range of 150 - 300 degrees
Centigrade while the wax has one between 50 and 60 degrees. Paraffin wax is
used for all sorts of things includeing cheap candles and waxed paper.
Actually I think you mean that paraffin has a "melting point" of about 60 o
C
Camphorated oil on the other hand I would suspect is not strictly necessary.
The oil part yes, but the camphor part was probably used as a preservative
as some of you may remember camphor balls or mothball ususally consisting of
napthalene and sometimes, yes you've guessed it, camphor.
Therefore, camphorated oil was probably used as an amplication for preseving
perishable non edible goods in the days of moths. Now all of this is some
educated conjecture but I hope it is of use to you. I would think that oil
would be sufficient.
It's hard to say, in the wet plate process they used to varnish the plate
with gum sandarac and in the formula they recommend oil of lavender. The oil
is added for flexibility and, as I was told, it has to be lavender.
I tried oiling papers with sunflower oil, it works fine but it goes rancid
over time and smells pretty bad,
so maybe the preservative is important. Paraffin (solid thing) works fine
but the paper is fragile after, it marks easily (at least thin paper I use
with ink jet printers).
I have an old formula here that I have never tried, but maybe it works, who
knows, it says:
"To make paper transparent:
Dip the paper in a bath at 80 o C of:
Parafin (solid) ............. 40 gr.
Linsen oil .................... 10 gr.
After the paper take up all the solution it cans, drain it fast and put it
between 2 sheets of blotting paper."
Will it work? Who knows, but why does he give the amount of oil in gr and
not in ml?
This formula dates from 1905, found it in a paper I have here and it has
other curiosities.
I am just looking up in a dictionary that camphor itself is a whitish,
translucent crystaline, pleasant-smelling terpene ketone, whatever that
means except that most ketones smell nice from what I can remember at
school, used in medicine and in the manufacture of celluloid. Ah ha! There
it is, the manufacture of celluloid. Is that not what one is doing when
applying the camphorated oil to the paper with paraffin? Probably not.
Will sulfuric acid damage the gelatin part of the photo paper?
I am working with an Arjo Wiggins Parchment paper called Linaje and they
told me that the transparency is obtained by immersing the paper in a
solution of sulfuric acid, washing, neutralising and buffering it after.
Anyway, whoever got a good formula I'm interested in knowing.
Cheers
Joao
P.S. I have an old formula for turning the wood black, but I don't know how
to translate it, maybe Guillermo will help, it says:
Extrato de Pau de Campeche .............. 15 gr. (what the ... is that?)
Cromato de Potassa ........................... 2 gr. (I believe it is
"Alumem de cromo" )
Agua .................................................. 1000 gr.
He says to dissolve the Campeche first in hot water and add the Cromato. The
solution is dark violet and becomes black in contact with the wood.
Dear Joao
Of course you are right; I was talking about the melting point.
Thanks for your formulae, I may use them one day when I want to make tracing
papers of particular quality.
All the best
Alexis
