File No. 626, titled “knot bleed,” has us examining a case of gumming, or sap leak, being faced by a Mr. Ely McCutchen, aka the “Bainsville Bleeder.”
Formerly known as the “Bainsville Bomber” due to Ely’s prowess in the ring as an amateur boxer, the unfortunate circumstances of Ely’s present moniker came at the hands of a Mr. Hank McFarlen, aka the “Huntsville Hurricane.” A formidable boxer in his youth, Ely’s strength permitted him to back his opponent into the corner buckle with a series of jabs, then with a haymaker-type swing, drop the bomb, which ultimately ended most of his bouts within a few rounds.
Matter of fact, the Bomber’s technique was so successful, most battles had him leaving the fight totally unscathed.
That is, until the Bomber’s first professional bout with the Hurricane, who’s speedy manner had the Bomber suffering his first real blow to the nose. Within moments, the Bomber was spouting blood quicker than a punctured fuel tank, with the bell to end the first round saving him from an early exit.
Entering the second round with basically a box of tissue paper stuffed up each nostril, the proud Bomber stepped towards his opponent, only to be met with a second lightning-quick blow to the nose. Once again, perfectly good O-negative blood spewing out at a rate of one quart a minute, and had every towel in the joint turning to red in an attempt to quash the bleeding.
In that moment, the Bomber, in a cruel twist of fate, became the Bleeder, and his career in boxing was over.
Fast forward 20 years. Our Mr. McCutchen is walking across his newly constructed, treated-lumber deck.
Surveying the general quality of the construction, Ely found himself barefoot, with his sandals having been left three steps back, essentially stuck to the decking surface. Equally gummed were the soles of Ely’s feet, and upon closer examination, Ely noticed sap extract and various other gummy deposits pooling around several of the decking plank knots.
With the former Bomber coming to the realization his deck was now bleeding, the little gummy pools of sap strangely turned to red, as our Ely experienced a dizzying, PTSD flashback. Minutes later, waking up on the deck with his face now stuck in a sap deposit, the Bleeder was at a loss as to why his decking was reacting in such a manner.
Essentially, treated lumber is a mixture of wood species that include spruce, pine, and fir, which has been infused with a copper formula to prevent insect infiltration and rot, then kiln-dried to a moisture level that can vary between 12 per cent and 15 per cent. At this moisture level, lumber maintains its structural strength, and accepts a nail or screw with lesser chance of splitting.
Although the wood’s been cut, it’s not quite dead, so there may be resins and sap residues that leak out of the knots, which is commonly referred to as knot bleed. Knot bleed occurs when the wood absorbs moisture, either through rain or general high-humidity circumstances, with this moisture pushing these natural oils and tannins to the wood surface.
So, can treated lumber which is displaying knot bleed be painted or stained? No, the moisture levels are still too high.
Is there a means of sealing a knot in order to prevent further knot bleed? Not really. Shellac and Bin type sealers may work temporarily, but the sap will bleed through regardless, somewhat marring the finish.
What’s the solution to knot bleed?
Ultimately, you’ll need to patiently let the knots bleed through until they’re dry, then scrape off the sap residue and sand the area clean before staining.
Testing for dry? In a sunny spot, tape (on all four sides) a piece of saran wrap to the top of a plank, then wait 20 minutes. If condensation appears under the plastic, it’s too soon to stain. When the plastic remains dry, it’s stain time.
With that, file No. 626 was closed.