Adhesive for Gluing Knots in Paneling

A heavy-bodied gap-filling formula might work best for knots. October 16, 2013

Question (WOODWEB Member) :
My small mill gets maybe 20% of its lumber high graded for a small kiln we have and is then to be planed wth a PH260 Logosol moulder. As the boards come out of the kiln and are sorted, some invite a preemptive glue job on a not so tight knot. What's the fastest and most effective adhesive solution to this problem?

Forum Responses
(Adhesive Forum)
From contributor M:
2p10 from Fastcap works well.

From Gene Wengert, forum technical advisor:
Knots are so dense and have so much sap or gum that they are difficult to glue with conventional adhesives. Oftentimes the adhesive cannot penetrate past the resin to attach to the wood. Clean the resin off with a solvent. Then try a more expensive adhesive such as epoxy. You could also use a construction mastic adhesive to get geometric or physical bonding, if the color of the adhesive is acceptable. These usually come in a tube and are applied with a caulking gun.

From the original questioner:
Thanks Gene. I'll be trying those approaches, especially your second suggestion. Epoxy would be more of a last resort as the product is not of great value per square foot.

From contributor R:
We use CA, commonly known as super glue for feather checks and knots before it goes into the moulder. Accelerator hardens the CA and speeds up the process and consolidation epoxy is a better choice than regular epoxy as it is thinner for the repair of rotten wood.