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How can I remove sap from lumber?

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Forum topic by NickyP posted 219 days ago 836 views 0 times favorited 6 replies Add to Favorites Watch
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NickyP

98 posts in 223 days


219 days ago

Topic tags/keywords: question trick tip

Long story short: I have milled down and squared up 2×4’s into legs for an outdoor table. After glue up, one of the legs oozed out a good stream of sap from a knot hole. I’d like to remove this sap prior to staining and finishing the table. Does anyone have a good solution?

-- "Never underestimate the power of a kind word, a good deed, or a table saw."


6 replies so far

View DrDirt's profile

DrDirt

2269 posts in 2242 days


#1 posted 219 days ago

Scrape the excess

Wipe down with lacquer thinner.

Seal with shellac, and use a gel stain.

Good luck – I don’t usually do any finishing with color on construction lumber.
Either a clear finish or I am painting it – never tried to stain.

-- "If we did all the things we are capable of doing, we would literally astonish ourselves." Edison

View Bill Davis's profile

Bill Davis

226 posts in 2424 days


#2 posted 219 days ago

Here’s a quote from Fine Wood Working magazine:

“Here’s how I got around the sap problem:
I began by scrubbing off as much of the sticky stuff as possible using rags and mineral spirits. Then, I cut off as much of the sappy edge grain as possible at the bandsaw and rough-cut my smaller components to size. From there, it was just a matter of baking the wood until the sugary sap crystalized and then hardened. I baked the pine at 160-degrees for a little over an hour—keeping a close eye on the oven for safety reasons. I found that the high temperature actually did two things: 1) it drove most of the sap up to the surface, where I could easily remove it with hand tools, and 2) it hardened any sap left behind in the wood, thus preventing possible “weeping” through my final finish in the future. In the photo at left, you can clearly see how the sap migrated to the surface, particularly via the end grain.

http://www.finewoodworking.com/item/41798/how-to-set-wood-sap

View gfadvm's profile

gfadvm

9540 posts in 1190 days


#3 posted 219 days ago

Mineral spirits works well to clean pine sap off my tools and hands so should work on wood.

Shellac will seal that sap very well and prevent bleed through.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View WDHLT15's profile

WDHLT15

981 posts in 976 days


#4 posted 219 days ago

In trees prone to sap, like conifers, the sap has to be “set” by heating up the wood to a temperature above the highest temperature that the wood will see in use. This done during the kiln drying process. Air dried wood does not have the sap “set”.

-- Danny, Located in Perry, GA, Forester, Wood-Mizer LT15 Sawmill

View NickyP's profile

NickyP

98 posts in 223 days


#5 posted 217 days ago

I ended up scrapping off excess with a paint scraper followed by wiping it down with mineral spirits and sanded to a smooth finish. Worked great! Thank you all for your advice.

-- "Never underestimate the power of a kind word, a good deed, or a table saw."

View Nomad62's profile

Nomad62

667 posts in 1458 days


#6 posted 212 days ago

Bills advice is best, in my opinion; the wood will continue to leak sap any time it gets warm/warmer than before, until it is almost empty which will take a long time. Best to heat it to 160, but well beyond its typical potential environment should be ok.

-- Power tools put us ahead of the monkeys

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