e, I pass the roller over the cold plate carefully
and with very slight pressure, repeating the process a number of times
and in various directions. This is an operation requiring skill. The
ground adheres only to the surface of the plate, without penetrating
into the furrows, although it is next to impossible to prevent the
filling up of the very finest lines. Having thus spread the ground, and
having assured myself that the lines are all right by the brilliancy of
their reflection as I hold the plate against the light, I rapidly pass a
burning paper under the plate. The ground is slightly heated, and
solidifies as it cools.

The varnish used in this operation is the ordinary etching-ground in
balls, dissolved in oil of lavender in a bath of warm water. It must
have the consistency of liquid cream; if it is too thick, add a little
oil of lavender.[12]

Both the plate and the roller must be well protected against dust.

It is not necessary to clean the roller after the operation; only take
care to wipe its ends with the palm of your hand, turning it the while,
so as to remove the rings of varnish which may have formed there.

If the lines are found closed, too much pressure has been used on the
roller; if the ground is full of little holes, the plate has not been
cleaned well, and wherever the surface of the copper is exposed the acid
will act on it. There is nothing to be done, in both cases, but to wash
off the ground with spirits of turpentine, and commence anew.

My plate is now in the same state in which it was when I withdrew it
from the bath. I stop out those parts which are sufficiently bitten,
and, guided by my proof, I can proceed to continue the biting which was
interrupted by the accident.

58. =Revarnishing with the Roller in Cases of Partial Rebiting.=--You
will find this method especially valuable whenever you desire to
strengthen passages that are weak in tone. And furthermore, having thus
revarnished your plate, you may avail yourself of the opportunity of
giving additional finish. But if, before revarnishing, you should have
burnished down some over-bitten lines in a passage which needs rebiting,
you will find that the shallow cavity produced by the burnisher does not
take the ground from the roller; such places are easily detected by the
brilliant aspect of the copper, and good care must be taken to cover
them with ground. Again, if, before proceeding to rebite, you should
notice certain passage