I'm curious if any of the forum contributors ever use shellac to seal pruning wounds.
The reason I'm asking is this: I recently pruned a Monterey pine for low and dead branches, resulting in sap drip. Someone asked me what I use to stop that, and I remembered reading a message somewhere about use of shellac to exclude insects from fresh wounds. I also know that is used to seal sap and stains from bleeding through painted wood.
It's not clear to me yet, whether or not shellac can actually arrest the dripping of pine sap.
Does anyone have personal experience they can share? Thanks.
Enjoy the link below.

Reply to post by Mark Goodwin, on June 05, 2002 at 13:31:39:

Mark, it may have been me talking about using shellac as a sealant.
If sap flow is not strong it may hold back "bleeding". So it should be applied immediately after the cut is made, which also meets the objective of sealing out decay organisms and insects.

If the sap flow is coming from the bark, though, I'm not sure I'd want to seal there, for fear of inhibiting callus growth. But maybe that fear, like the "don't ever paint" message, is is at times not applicable.

Nice story--thanks for the link.

Reply to post by Guy, on June 05, 2002 at 13:31:39:

A few observations.

I have no experience with trying to stop sap flow, I'd guess you'd have to experiment. No experience with pines, but in the NE we always avoided pruning sugar maples and dogwoods from late winter until partial leaf out if sap flow was an issue.

I can never recall the citation but there is something fairly recent from Cornell about possible fungal exclusion using shellac.

I do not recall the exact reason but the old timers always used "orange" shellac on tree wounds. In recent years I've only found "amber (formerly orange)" on the labels. No clue what the difference is.

I would not be concerned about inhibiting callus growth. In the old days of cavity work proper practice was to coat the cut cambium edge at the cavity opening immediately with orange shellac to prevent dessication and die-back. You never cut more than a few inches of bark edge at a time without pausing to apply the shellac. The idea was to promote a smooth callus edge which would overgrow the filling material.