It is found the best results are obtained by mixing the phosphorescent
substance with a colorless varnish made with mastic or other resinous
body and turpentine or spirit, making the paint as thick as convenient
to apply with a brush, and with as much turpentine or spirit as can
be added without impairing the required thickness. Good results may,
however, be obtained with drying oils, spirit varnishes, gums, pastes,
sizes, and gelatine solutions of every description, the choice being
varied to meet the object in view or the nature of the article in hand.
The mode of applying the paint, varnish, or wash will also depend upon
the circumstances of the case. For example, it may be applied by a
brush, as in ordinary painting, or by dipping or steeping the article
in the paint, varnish, or wash; or a block or type may be used to
advantage, as in calico-printing and the like. For outdoor work, or
wherever the surface illuminated is exposed to the vicissitudes of
weather or to injury from mechanical contingencies, it is desirable to
cover it with glass, or, if the article will admit of it, to glaze it
over with a flux, as in enameling, or as in ordinary pottery, and this
may be accomplished without injury to the effect, even when the flux or
glaze requires a red heat for fusion.
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