Pitch is the resinous sap in evergreen trees, including spruce, fir, pine, hemlock and cedar. Pitch is what has preserved the piece, and it gives some wood its color. It comes in many forms from quite gooey to crystalline and hard. It can run in streaks, fill cracks, cavities or permeate the entire piece. It is often necessary to try different treatments to find which one works for the kind of pitch you are dealing with in a specific piece. The goal is to control the pitch if removal is not possible.
For surface pitch or small pockets
Oil soaps – apply full strength, wait 20-30 minutes and scrape and/or rinse off with hot water.
-Murphy’s Oil Soap, Verax liquid soap, Goop, Go-J0, dishwasher liquid (caustic so wear rubber gloves)
-Commercial pitch removers: Turtle Wax Bug and Tar Remover (not the spray can), Bruce Deep Cleaner for Wood, Chain Saw Pitch Remover, or any other pitch removers.
Isopropyl Alcohol – apply to wood with cloth or swab of cotton.
-Soaked cotton can be stuffed into holes, cracks, and pocket of pitch: allow to sit over night to draw out the pitch.
-Use repeatedly to wipe off surface to remove sticky pitch while sanding or using an abrasive. Wipe wood with dry cloth and continue cleaning. Does not darken wood.
WD-40 – can be used to contain or stabilize the pitch. Use sparingly, wipe off quickly, then use brush or scraper.
– It can be used to remove powdery pitch with a stiff brush.
– Will bring out the color and may glaze some areas. If it turns dull black, needs more cleaning
Turpentine – Follow same procedure as with alcohol
– May bring out pink tones in woods such as pine or cedar
For permeated wood or large pockets of pitch
Heating– Use of heat gun brings the pitch to the surface
– Apply in short painting-type strokes – wipe off immediately, with a cloth, steel wool or sandpaper soaked in alcohol.
– Be careful, the pitch will be hot
– The alcohol will help dry the surface; take care because the alcohol is flammable.
– Add capful of Murphy’s Oil Soap to water in a large designated pot (pot will never be the same) and bring to a boil.
– Immerse the wood for a few minutes until the pitch floats to the surface of the water.
– A heavy piece may need more time in the water.
– Remove from water, wipe off pitch
– For pieces too big for pots, a cup can be used to pour the soapy hot water over the wood. Wipe off pitch as it appears, can use alcohol or Murphy’s on cloth.
– For thin pieces, just dip the piece in and out of the water to prevent it from warping.
– Procedure may be repeated if needed.
– Treatment may appear to take the life out of the wood, but it returns during sanding and finishing; a working oil such as 70% boiled linseed oil and 30% turpentine can also be applied.
– Place wood on a rack over the water in a designated pot.
– Bring water to a slow boil and steam until pitch appears on the surface.
– Wipe off as described above
– Heat oven to 150-200 and place wood on double sheet of aluminum foil.
– Watch carefully until pitch comes to the surface.
– Remove and wipe off with alcohol. May be repeated.
– Caution – may darken or warp wood
Freezing – works best on crystallized pitch on the surface or in pockets
– Place wood in plastic bag and leave in freezer (or outdoors if below freezing) for a few days
– Then chisel or tap pitch sharply; it should shatter or break up easily.
– Caution – can cause surface checking or deepen cracks.
– If a solid piece of burl has a hollow center filled with pitch, it may not be a good idea to try to remove all of it (may cause the wood to shrink or crack).
– If pitch is solid, leave it; if very soft or sticky, remove only what can be removed from the surface easily.
– WD-40 seems to seal in pitch.
– Some pieces are so permeated with pitch that if you remove all of it, the piece will simply fall apart. Remove what you can from the surface, then finish. Or heat to bring the pitch to the surface, let it cool and glaze the surface. Then apply another finish or bone and polish.
For white pitch along grain lines
A wood-burning pen or tool can be effective
Removing pitch from tools
Use alcohol, turpentine or any pitch removing products listed above.