>>> surface molds, it is like putting icing on the donut. yum-yum.
John Leeke, what say you about boiled/unboiled linseed oil in treating
wooden
gutters?  My copy of your practical report is in Massachusetts, and I'm in
NYC.<<

Linseed Oil: good food for the same organisms that eat wood. Why attract
them to wood you are trying to protect? In the past I have used it in west
and south gutters (which dry out due to sun), but no longer use it even
there. We will sometimes consolidate a porous weathered wood surface to be
painted by applying an alkyd resin product (Kyanoil (no longer available
under that name), or alkyd resin varnish cut down), especially when we do
not want to sand or scrape off the weathered wood down to sound wood because
we want to preserve the texture of the surface. I think the only reason we
started using linseed oil was due to tradition, not good thinking based on
practical experience. After 30 years experience I no longer use it on
exterior woodwork. Even for furniture finishing work I've shifted over to
tung oil.
I just took a look at some of my dad's linseed oil finish recipes....Yikes!
they actually look historic, 1920s, yellowing paper, worn edges. I'm sitting
on a chair he made back then with a linseed oil finish. In the 1950s he and
I renewed the finish with linseed and it still looks good, doesn't get
sticky in the humid summer heat, in general performs well. I suspect that
linseed oil from the the 20s & 50s is different than the linseed oil we get
today.

John Shellac-o-rama Leeke