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How to choose the right finish, Part 4

In this article we'll be looking at the ease of application, health
concerns and ease of repairing finishes.

Ease of Application:

One overriding factor that must be taken into consideration here
is:  How fast does the finish cure?

If a finish cures fast we can put more coats on faster.  The
downside is that the finish can cure too fast causing it to smear if we
drag our brush or rag through it again.  If a finish cures slowly we
can cover large areas without fear that it will start to get
sticky, which is great for large pieces.  The downside is you must
work in a dust free environment due to the possibility of dust
settling on the finish before it cures.   You can get around this
somewhat by wiping off the excess finish so that it will cure
faster, but many more coats must be applied.   

The easiest finishes to apply by hand are:  Oil, oil blends, wiping
varnish (thinned varnish), and gel varnish.

Oils and oil/varnishes cure slowly, as does varnish. Water base
dries faster than varnish but not by much. Shellac cures fast and
brushed on lacquer cures slow enough to be able to brush on.

Health Concerns:

Finishes that can be applied by hand that cause the least health
problems are linseed and tung oil, water base and shellac.  Linseed
and tung oil contain no solvents and water based finishes contains
only a small amount.  The solvent for shellac, denatured alcohol, is
relatively safe unless its ingested or breathed for a long period
of time.  

All the finishes we've talked about are combustible except water
based so avoid using them around flames or sparks.

All finishes have some degree of odor to them.  It's never a good
idea to breathe in solvents so one of two things should be done. Use
the finish outdoors, or use a respirator that is approved for use
with the finish you're using.

One more point about the safety of finishes.  All finishes are safe
to be in contact with food after they have cured completely.  This
doesn't come from me but from the FDA.  All the metallic additives
used are safe once they have cured.  This is due to lead no longer
being used in finishes since the 1970's.

Ease of Repairing:

One rule of thumb to keep in mind:  The thinner the finish, the
easier it will probably be to repair.  Wax, oil, oil/varnish,
shellac and brush on lacquer are all fairly easy to repair.
Varnish and water base are the hardest to repair.

Craig Stevens
Woodworkers Resource