OUP Plate Printing & Restoration Process
OUP
Plate Printing & Restoration Process
The following is from an old article that
appeared in a journal a few years ago…yes I do look a bit (allot) younger!
The printing process is as follows and is described as part of the work I have done working with the archives of the Oxford University press to restore and archive some of the plates that had been damaged and need restoration and preserving.
On receipt of the plates the first task was
to identify what damage had been done and what coating had been used to protect
the plate. All the plates had already been printed several thousand times so
some loss of clarity was only to be expected. In some instances this made
printing difficult, but mostly due to the quality of the copper and the depth
of the engraved line, the printing was reasonably straightforward.
Many of the plates had been given a coating
of white wax that was easy to remove on a hot plate; these plates tended to be
the most badly damaged since moisture had crept under the wax, causing severe
greening of the plate surface and occasionally damaging the surface of the
plate by corrosion.
To remove this effect the plates were polished with a mixture of whiting, water and ammonia. Some of the plates had been entirely unprotected and had suffered from very serious surface corrosion. In these cases there was no alternative but to use a more abrasive metal cleanser. I felt it was important to clean the surface of these plates to prevent any more surface corrosion and etching.
To remove this effect the plates were polished with a mixture of whiting, water and ammonia. Some of the plates had been entirely unprotected and had suffered from very serious surface corrosion. In these cases there was no alternative but to use a more abrasive metal cleanser. I felt it was important to clean the surface of these plates to prevent any more surface corrosion and etching.
Some of the plates had also been exhibited
under glass and were coated in a very resilient clear varnish, which was easily
removed with white spirit and some patience. Others had been recently reprinted
(1950s) and had received the traditional stop out coating, which in this case
had not stood the test of time and had become brittle and flaked of the plate.
It was obvious that a different stopout should be used to protect the plates.
After close investigation of the various modern protective coatings I felt that after cleansing and printing, two thorough layers of rhinds (a mixture of bitumen, turpentine and beeswax ) stop out would offer the best protection. Rhind's being far less brittle, but very hard wearing. Once coated the restored plates were carefully wrapped in a single sheet of glassine (acid free paper) for further protection.
After close investigation of the various modern protective coatings I felt that after cleansing and printing, two thorough layers of rhinds (a mixture of bitumen, turpentine and beeswax ) stop out would offer the best protection. Rhind's being far less brittle, but very hard wearing. Once coated the restored plates were carefully wrapped in a single sheet of glassine (acid free paper) for further protection.
When printing the plates (after some amount of trial and error) I
found that the plates responded best when printed on BFK Rives Heavyweight
paper (white 270g) an acid‑free, mold‑made rag paper, using a blanket
combination of one swanskin and two frontings. To determine how to set the
pressure for the press, plate and blanket combination I place the plate on the
press bed cover the plate with some dry paper and the blankets. Using a very
light pressure setting, the plate is 'dry ' printed.
Depending on the embossed impression of the back of the plate on
the dry paper the pressure is either increased or decreased. In this instance
the press was set at a moderate to heavy pressure.
The printing process I use is as follows;
firstly the paper was soaked in a bath of water for one hour, then placed
between wet blotters and put into a plastic envelope overnight. The plates were
then prepared for printing and using a smooth, clean, rounded piece of squeegee
(a small strip of polyurethane), the advantage of this particular technique as
opposed to a dabber or roller is one of speed and personal choice (see fig 1.),
Fig 1.
The ink is carefully applied to the plate
using a minimum of warmth from the hot plate in order to have as little effect
on ink viscosity as possible. Then using a stiff tarlatan or cheese cloth,
softened by hand to eliminate all risk of accidentally scratching the plate
(see fig 2.)
Fig 2.
Carefully with a gentle circular movement
wipe the plate.
Fig 3.
Finishing off the plate with a tissue paper wipe (see fig 3.),Which is a very efficient way of removing the
last remnants of plate tone left on the plate and finally a hand wipe with
whiting (see fig 4.),
In order to sharpen the clarity of the
engraved line by gently bringing the ink up out of the engraved lines. The bed
is then run through the press slowly without stopping, in order to allow the
rollers and blanket combination to give the best impression from the plate (see
figs 5, 6.).
Fig 5.
Fig 6.
After printing the print is placed between blotters with an interleaving of acid free tissue. They are left overnight (24hours) under weight (commonly a heavy board or 4mm sheet of glass) then the damp blotters are replaced by dry and the 'stack' is placed under heavy weight, usually a heavy board and a lithographic stone. After five days the prints are removed from the stack and the excess paper around the boarders removed or 'torn down'. In the case of these prints, I used a three-inch boarder. For presentation and archival storage each print is placed in an acid free folio with an interleaving of acid free tissue and glassine.
