Barbara
Thornton wrote:
We plan to build a log cabin in the woods. We are looking
for an interior finish with UV protection for the white pine logs. We do
not want the yellowing effect in years to come. Does any of your interior
coating products contain a UV inhibitor? Also, which of your products would
give us the best exterior protection for a white pine cabin in the woods
of Central Ohio. Our summers can be quite hot and humid. In the course of
the year, we usually experience sufficient rain and snow; some years more,
some less.
Thank you.
Barbara,
Yellowing of the logs is caused by various
mechanisms. There are clearer acrylic resins that don't have the inherent
yellow/amber cast that oil modified polyurethanes and alkyd resins have.
However, the logs themselves will go through color changes even if the varnish
you apply on the logs is composed only of acrylic resins. True, your logs
will initially look closer to new bare wood with the clearer acrylic resins
but over time, due to oxidation, indirect and direct UV light, and even
photons from your light bulbs, the wood will slowly change and darken. UV
absorber additives would help to prolong the change, but these additives
are not 100% UV blocking plus the UV absorbers has a limited life to them.
They are also very expensive. I tell owners to have their windows coated
with a UV film. These UV plastic window films are much more effective in
slowing down the negative effects of UV than additives in a clear varnish.
Regardless, your logs will change color over time. Continental manufactures
a transparent water based varnish called PolySeal. It is composed of polyurethane/acrylic
resins. PolySeal emits such an incredibly low level of fumes that it is
very pleasant to work with in an indoor environment.
Michael McArthur
Hi.........
We will be coating our interior logs of our Wisconsin Log Home
with PolySeal. Before deciding on the color, I need to know if you could
tell us whether we would obtain UV protection if we were to mix Amber 50/50
with Crystal? We would like to keep the interior as light as possible but
we do want UV protection from the sun. Our house has a lot of glass and
I am concerned that the pine logs will darken from the sun. Looking forward
to hearing from you.
Lowell Isenberg
Dear Lowell,
Amber PolySeal will provide
some additional protection against UV. However, there is no Transparent
interior varnish that will provide a significant barrier against the color
changing effects of UV radiation. The original color of the logs will change
because of their exposure to sunlight, indoor light and oxygen. They will
slowly and imperceptibly darken over a period of time. There is no transparent
coating that you can put on the logs that will stabilize indefinitely the
fresh cut color of your new logs. However, pictures and other types of items
hung on the walls will shield the wood from the color changing effects of
the various light sources in the house. Consequently, those areas that are
covered by wall hangings will remain virtually unchanged in color. If a
picture or wall hanging is removed after a period of time (a year or so),
a lighter, shadow image of the framed area will be visible. Presently, there
is no clear coating technology that will prevent such an occurrence.
Thanks
for asking.
Michael McArthur
Continental Products Co.
Jim Lewis wrote:
We
are looking for a sealer for log siding and knotty pine siding both on the
interior of our home. We have used a product called Stays Clear to seal
this type of wood in the past but have found it to darken over time. We
would like more information on your products that may fit this application.
We have a number of wall hangings and when these are moved you can see the
difference in color (lighter) behind the hanging as compared to the wood
beside it. Can you solve this problem for us with your products? We are
putting in new siding materials right now.
Thanks,
Jim Lewis
Jim,
There
is no clear interior varnish or sealer than can prevent the darkening of
your paneling. Indirect sunlight as well as oxidation of the wood contributes
to the darkening effect of both the wood and the clear coating. There are
plastic film products that are applied onto the interior glass portion of
the window in order to reduce the intensity of UV. They do help slow the
fading of curtains and fabric and will help to retard the color changing
effects of sunlight on the log walls.
Michael McArthur
