Q: I paint in oil and acrylic, and I've successfully used an
acrylic final varnish for both. I seem to have misplaced this final
varnish recipe, but I believe that it was part gloss and part matte.
Can you recommend a recipe of this type for me?
A: Because new products, including new synthetic varnishes,
become available with some frequency, it is best to start with a fresh
recipe and to perform a few tests to get the desired results. To
formulate a final acrylic varnish with the preferred finish-which is
somewhere between matte and gloss and is suitable for use on both oil
and acrylic paintings-begin with a mixture of 1⁄2 matte synthetic
varnish and 1⁄2 gloss synthetic varnish. Mix a small amount of solution
and apply it over two different painted surfaces, one oil and one
acrylic. When the test surfaces dry, you will be able to determine
whether to add more matte or more gloss, or whether the final varnish
is just right. Keep a record of the amounts of each type of varnish
used and then write down the final recipe.
Read the labels on synthetic varnishes carefully to become familiar
with the ingredients. For example, a gloss varnish may contain mineral
spirits with a ketone resin, while a matte varnish may have those same
ingredients, plus some translucent liquid wax. These ingredients are
compatible and, when blended together, will produce a satin finish
between a gloss and a matte.
Synthetic varnishes are more permanent than their natural
counterparts or those made with damar and mastic; they are also more
elastic and do not yellow or become brittle with age. Regarding
conservation concerns, synthetic varnishes are reversible with
good-quality mineral spirits or turpentine. It is important to mention
that although synthetic varnishes can be used to varnish oil paintings,
unlike natural resins, they do not combine with oil paints to make
Q: I have been given an oil painting to repair by a friend
who has a nostalgic connection to the artist. The painting is about 40
years old and has been stored in a garage with many others, is dirty,
and has a dull appearance. It has also been chipped in a number of
places, primarily along the stretcher bar, and the chips are rather
large in size. When I received the painting, I noticed many cracks
along the top as well, which lead me to believe that the painting will
crack and chip even more. The painter was untrained and probably did
not use professional-grade art materials and also probably used
turpentine, both as a thinner and as a medium.
A: Without lamenting the number of paintings that have been
harmed by amateur conservators and extolling the virtues of
professional conservation, it is still necessary to give fair warning
that professional treatment is the only answer. Even so, there are no
guarantees the painting can be improved and that treatment will not
cause harm to the already damaged work. The following information,
then, is only suggestions on how you can care for paintings when
professional care is not an option.
First, consider some of the causes for the conditions that you
describe. Oil paintings stored in the dark will often turn yellowish,
especially the whites, and with moisture added to the equation the
situation worsens. It is difficult to gauge the atmosphere of the
garage where the painting was stored, but extreme changes in
temperature can be just as damaging to the stretcher bars, causing
warping and splitting, as to the paint surface itself, which can suffer
from the expansion and contraction of the support.
The chipping of the paint along the stretcher bars sounds like
flaking, a condition that jeopardizes the integrity of the whole
painting. Flaking is usually caused by exposure to extreme atmospheric
changes. If that is the case, any attempt at cleaning the painting will
only cause more damage to the picture. Proceed with extreme caution,
and as soon as any cracking or flaking appears on the surface, suspend
further treatment to the painting.
The dirt, on the other hand, sounds superficial. If it is, use
crumbs of soft bread kneaded like a plastic eraser to gently clean off
the painting. If there is no change to the surface of the work, you can
gently vacuum the reverse side of the canvas. Do not attempt to vacuum
the front side of the canvas, however, because the paint chips will be
lost. Since the painting is thoroughly dry, you can also rub it gently
with a piece of cotton moistened with a tiny amount of turpentine or
solvent; but this is only if the bread crumbs do not remove the dirt.
Since the materials of the painting are not known for certain, be
extremely cautious when using any solvent. Use small cotton swabs for
this procedure and change each one as soon as it becomes dirty.
Turpentine is a strong solvent and must be managed very carefully.
Normally, lost areas of paint can be filled in with a reversible
mixture of stiff glue gesso that handles like putty. When the holes are
filled, they can be retouched, which, in picture restoration, is called
in-painting. Usually a reversible paint, one that may be different from
the paint used in the original work, is applied. In this case, however,
it is advisable to leave the chipped areas of the painting untreated,
especially since they are located at the edges of the painting. Based
on the description of the painting's condition, the less it is handled,
Last, there is the issue of the painting's surface appearing dull.
Varnish provides a protective coat to the surface of an oil painting
and unifies an uneven surface. It can also add a soft glow to a dull
surface. The varnish should not be too glossy, however, or the picture
will be difficult to see; conversely, the varnish should not be too
matte, or it will not protect the picture. A semigloss varnish, then,
is usually the ideal solution. In this instance a spray-varnish coating
is recommended, because it is less invasive than brush-on varnish. It
is important to varnish on a dry, sunny day. Remove any dust from the
room and keep all the tools free from moisture. Be sure there is proper
ventilation in the room because spray varnishing introduces fine
particles of resin and solvent into the air. Always wear protective
gloves and an organic vapor respirator when varnishing.
by Jane Sutherland