een deluded by the known way of
distilling water with the aid of sunshine without concentrating the
rays of the sun, based upon the solubility of water in air, viz.: Air
holds more water in solution (or suspension) in a warmer than in a
cooler degree of temperature; by means of a simple apparatus
sun-heated air is guided over sun-heated water, when the air saturated
with water is conducted into a cooler, to give up its water again. But
water has an influence toward hastening to blister paint; it holds the
unhardened woodsap in solution, forming a slight solvent of the oil,
thereby loosening the paint from the wood, favoring blistering and
peeling. There is a certain kind of blister which appears in certain
spots or places only, and nowhere else, puzzling many painters. The
explanation of this is the same as before--soft paint at these spots,
caused by accident or sluggish workmen having saturated the wood with
coal oil, wax, tar, grease, or any other paint-softening material
before the wood was painted, which reacts on the paint to give way to
air pressure, forming blisters.

The second cause of paint blistering from the ingredients of the paint
happens between any layer of paint or varnish on wood, iron, stone, or
any other substance. Its origin is the gaseous formation of volatile
oils during the heated season, of which the lighter coal oils play the
most conspicuous part; they being less valuable than all other
volatile oils, are used in low priced japan driers and varnishes.
These volatile oils take a gaseous form at different temperatures, lie
partly dormant until the thermometer hovers at 90 deg. F. in the shade,
when they develop into gas, forming blisters in airtight paint, or
escape unnoticed in porous paint. This is the reason why coal-tar
paint is so liable to blister in hot weather; an elastic, soft
coal-tar covering holds part of its volatile oil confined until heated
to generate into gas; a few drops only of such oil is sufficient to
spoil the best painted work, and worse, when it has been applied in
priming, it settles into the pores of the wood, needing often from two
to three repetitions of scraping and repainting before the evil is
overcome. Now, inasmuch as soft drying paint is unfit to answer the
purpose, it is equally as bad when paint too hard or brittle has been
used, that does not expand and contract in harmony with the painted
article, causing the paint to crack and peel off, which is always the