DOI Page / Citation link:
https://doi.org/10.11588/diglit.19571#0154
14o THE ARTIST'S ASSISTANT.
Pit-coal may be ufed in the furnace, where enamel
is burnt with the fixt muffle, or in coffins ; which
is indeed one principal conveniency attending the
ufe of them ; as it faves a considerable expence of
charcoal. But where the open muffle is ufed. char-
coal alone fhould be employed ; as the fumes of mi-
neral coal are very detrimental to fome colours, and
deftruclive of the grounds, if whitened by arfenic,
as the common white glafs.
The colours being prepared, they muft be reduced
to powder by due levigation, and warning over,
where they are required to be extremely fine, and
there is no unvitrified fait in the mixture. They
muft then be tempered on a china or Dutch tile
with oil of fpike or lavender, to which moft artifts
add likewife oil of turpentine ; and fome (but I
think erroneouilv, as I have before mentioned) a
little linfeed or olive oil, and in this ftate they are
to be uied as paint of any other kind. But it fhould
be avoided to mix more of the colours with the ef-
iential oils than will be immediately ufed; becaufe
they dry away extremely fait, and would not only
be wafted, but give a cohefion to the particles of the
colours, that would make them work lefs freely
when again diluted with oil.
The colours being thus laid on the pieces to be
painted, the proceeding muft be in all refpe&s the
fame as with the grounds, in whatever manner they
are to be burnt, either in the muffles or coffins.
But greater nicety muft be obferved with 7-efpecb to
the fire, as the effefts of anv error in that point
are of much greater confequence in the burning
the colours than the grounds; efpecially if the
white
Pit-coal may be ufed in the furnace, where enamel
is burnt with the fixt muffle, or in coffins ; which
is indeed one principal conveniency attending the
ufe of them ; as it faves a considerable expence of
charcoal. But where the open muffle is ufed. char-
coal alone fhould be employed ; as the fumes of mi-
neral coal are very detrimental to fome colours, and
deftruclive of the grounds, if whitened by arfenic,
as the common white glafs.
The colours being prepared, they muft be reduced
to powder by due levigation, and warning over,
where they are required to be extremely fine, and
there is no unvitrified fait in the mixture. They
muft then be tempered on a china or Dutch tile
with oil of fpike or lavender, to which moft artifts
add likewife oil of turpentine ; and fome (but I
think erroneouilv, as I have before mentioned) a
little linfeed or olive oil, and in this ftate they are
to be uied as paint of any other kind. But it fhould
be avoided to mix more of the colours with the ef-
iential oils than will be immediately ufed; becaufe
they dry away extremely fait, and would not only
be wafted, but give a cohefion to the particles of the
colours, that would make them work lefs freely
when again diluted with oil.
The colours being thus laid on the pieces to be
painted, the proceeding muft be in all refpe&s the
fame as with the grounds, in whatever manner they
are to be burnt, either in the muffles or coffins.
But greater nicety muft be obferved with 7-efpecb to
the fire, as the effefts of anv error in that point
are of much greater confequence in the burning
the colours than the grounds; efpecially if the
white