John
Leeke's Historic HomeWorks™
Issue #35
Copyright 2007 John Leeke
Gutter
Talk
Do you
recommend, as my regular hardware store owner does, preserving
gutters with a 50/50 mix of raw (not boiled) linseed oil and paint
thinner - or do you recommend something better? I always thought
Cuprinol was the best.
We no longer
use the traditional linseed oil and turpentine mix, since it has
been scientifically demonstrated to support the growth of mold and
mildew which can lead to fungal decay and insect attack. It's like
putting "frosting on the cake" for the critters that eat
wood. The turpentine in the traditional mix is somewhat poisonous,
but substituting paint thinner would be like adding vanilla
flavoring to the frosting.
There is a
class of products called water repellant preservatives that make a
better gutter treatment. Oils or waxes in these products help keep
liquid water out of the wood, yet allow water that does get in to
pass back out as vapor. This is exactly the water handling
function you want for gutter troughs. Chemicals act as
preservatives to limit the growth of mold and mildew at the
surface.
Cuprinol is a
brand name under which several exterior wood finish products are
marketed. I just called Cuprinol technical support to learn the
product has been canceled in the
United States
this past year, some may still be available in the supply lines.
Any product that is described as a "water repellant
preservative" would be OK to use in gutter troughs. Other
common water repellant preservative products are Chevron Shingle
Oil and Thompson's Ultra Wood Sealer.
Years ago we
got tired of trying to keep up with the paint industry
manufacturers’ constant changing of products and buying each
other out and discontinuing products. So, we now make our own
water repellant preservative according to the Forest Products
Laboratory document, “W.P.R.: Water Repellants and Water
Repellant Preservatives.” It contains a recipe and method for
making your own gutter treatment solution.
“A WR or WRP
is a solution that gives wood the ability to repel liquid water,
such as rain and dew. They do this because they contain a wax like
substance. By repelling water, they resist decay and stain by
denying fungi that cause these conditions the moisture they need
to live. A WR or WRP also reduces water damage to the wood, such
as the excessive swelling and shrinking that leads to cracking and
warping.” –W.P.R.
We substitute oil-based alkyd resin varnish or oil-based alkyd
resin pre-treatment (such as Penetrol) for the boiled linseed oil.
Remember to clean your wood gutters twice a year and treat them
with a water repellant preservative every two or three years.
Resources:
Get the Forest Products Laboratory’s “Water Repellants and
Water Repellant Preservatives” document on the internet at:
http://www.fpl.fs.fed.us/documnts/fplrn/fplrn124.pdf
Learn more about gutter maintenance and repair in John’s Wooden
Gutter report: http://www.historichomeworks.com/hhw/reports/reports.htm#Gutters
Contact
Leeke directly for answers to your questions and more information
on techniques for restoring and maintaining your historic
building. Write to John Leeke, Preservation Consultant at
26 Higgins St.
,
Portland
ME
04103
, 207 773-2306; or by E-mail at johnleeke@HistoricHomeWorks.com
or visit his Internet Web Site at www.HistoricHomeWorks.com.
Live Video Conferences &
Replays:
http://historichomeworks.com/hhw/conf/vidconf.htm
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http://historichomeworks.com/forum/
© John Leeke
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