Technical Tip of the Week
As hot weather approaches we begin getting calls about resin bleeding out of logs and what can a
homeowner do to stop it. Some people may call it sap or pitch or resin but it's all the same and short
of replacing the log or logs that are bleeding there is nothing anyone can do to stop it from occurring.
Resin is made of up of a combination of hydrocarbon compounds and is produced by most trees but
particularity softwood species like spruce, pine and fir. Amber is fossilized tree resin. There is no
way to outwardly determine if a log will bleed resin or not. Trees may form pockets of resin due to a
past injury or for a variety of other reasons and when that tree is harvested it may take months or
even years for the resulting log to begin to bleed resin.
Tree resin is typically thick and viscous but during the summer months on the sunny sides of log
homes the logs can get hot enough for the resin contained in pockets and knots to become quite fluid
and begin to bleed out of the wood. Once this begins it is virtually impossible to halt the flow of the
resin out of the wood. It will easily burst through coatings like paint or stain and form an ugly sticky
mass on top of the finish. One problem with resin bleed is that even if it is removed the log may
continue to bleed each summer for many, many years. Most of the time it's just a few logs on a wall
that bleed resin but occasionally we see a home where just about every log on a south or west facing
wall bleeds resin and when that happens it makes for a very unhappy homeowner.
So is there anything that we can we tell customers who call in asking about resin, pitch or sap bleed?
Since the resin is soft and sticky it is impossible to wipe off the surface without making an even bigger
mess. It's not water soluble so it can't be washed off and even solvents don't have much effect on it
other than to spread it around. Small spots of resin can sometimes be cleaned off with alcohol but if
there is a finish present the alcohol can also destroy the finish. The only effective method of
removing resin that I'm aware of is to chip it off but in order to do this the resin must be cold enough to
become brittle. In the north it's best to wait for a cold winter day but in the south where cold days are
far and few between you can use an ice pack to cool down the resin then try to chip it off. Sometimes
this works and sometimes it doesn't but it may be worth a try. The problem is that come summer the
bleeding will most likely start up again.
One of the biggest challenges relating to resin bleed is when it occurs on bare wood prior to the
application of a finish. Since there is no effective way to totally remove the resin the finish ends up
being applied on top of it. When the wall heats up and the resin starts flowing it carries the finish
along with it leaving unsightly spots of exposed bare wood. Again there is not much that can be done
to end this process until the resin eventually stops bleeding out of the wood.