^g PAINTING MATERIALS
it is more likely to have been a hard copal, possibly indistinguishable from amber
even to the varnish makers. Large quantities of balsams were sometimes used,
as is shown by a recipe consisting of 3 parts Venice turpentine, 3 parts oil, and
I part mastic.
Theophilus, in the early XII century (Schedula diversarum artium] (see Berger,
III, 57), describes the process of varnish making. According to him, the resin was
melted to a clear liquid and was then poured into hot oil. The solution was beaten
and stirred until a drop, after cooling, remained clear and was of the desired
consistency. These same principles are followed today in the manufacture of oil
varnishes. Laurie (Materials of the Painter's Craft, p. 287) is of the opinion that
the common varnish used from the IX till late in the XV century consisted of a
fairly soluble resin, either sandarac or mastic, or both, dissolved in linseed oil
and having pica grecay which is now called 'colophony,' added in considerable
quantities. In the early XVII century, oil gives way as a constituent, and spirit
varnishes, that is, resins dissolved not in oil but in turpentine or natural naphtha,
and later in alcohol, are mentioned. They originated, apparently, in Italy, and
a recipe is given in a treatise supposedly published about 1740 (Barry, p. 4), for
an oil varnish thinned with turpentine.
In the five centuries between Theophilus and Albert! there developed an
appreciation of the different varieties of resins. Matthioli, in his commentary on
Dioscorides published in 1544, makes the observation (Barry, p. 5): *. . . the
juniper produces a resin similar to mastic called (though improperly) san-
darac. With this resin and linseed oil is prepared liquid varnish, which is used
for giving lustre to pictures, and varnishing iron/ Pine balsams are frequently
mentioned, and probably the Flemish painters used balsam more than the painters
of Italy where the climate was much drier. De Mayerne (Berger, IV, 185, 259,
and 269), writing in the XVII century, gives recipes used by Flemish painters
and speaks of Venice turpentine as a suitable substance for the preparation of
varnishes, advising that it should be dissolved in spirits of turpentine, with the
occasional addition of sandarac or mastic or a few drops of oil to give it toughness.
Early Flemish paintings have been supposed to owe their durability to the fact
that the vehicle was an oil varnish which fixed the painting without the need of
a further coating. Records of the methods of the Van Eycks (XV century) and
* their followers are so scanty that it is impossible to speak with certainty of the
ingredients they used. Many authorities on this period affirm that the vehicle
was oleo-resinous. Laurie considers it improbable that amber varnish was seri-
ously employed in painting, although Rembrandt is said, by his contemporaries,
to have used it. It is likely that the so-called amber varnish purchased in shops
was not made from the fossil resin, for true amber yields a dark, runny varnish
which dries badly.
Modern literature on resins and their use in painting may be said to start
with Watin, who published The Art of the Painter, Gilder and Varnisher in 1778.