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Sap leak through-what to do?

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Forum topic by A Slice of Wood Workshop posted 1105 days ago 4588 views 0 times favorited 8 replies Add to Favorites Watch
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A Slice of Wood Workshop

886 posts in 1768 days


1105 days ago

Topic tags/keywords: sap leak poly fix finish

I made a coffee table just recently. I stained it and now adding layers of poly onto it. I’ve got a major problem now and was wondering if there is anything that I can do to fix it. I’ve joined 3”strips together and now sap is leaking through where I have joined two boards together. Is there anything I can do or will time just cure it?

-- Tim- http://www.asliceofwoodworkshop.com; Twitter-@asliceofwood; Facebook-http://www.facebook.com/asliceofwood


8 replies so far

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ajosephg

1839 posts in 2156 days


#1 posted 1105 days ago

I’ve never had this problem on furniture projects, so take what I say with a grain of salt.

If this was something that was to be painted, the sap area could be sealed off with shellac or kilz. But that would mess up your desired finish, so I think you’ll have to rip out the section that has the sap in it and glue it back together, then refinish it.

-- Joe

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Howie

2656 posts in 1518 days


#2 posted 1105 days ago

I think Joe is right. Rip out the sappy board. If it’s in a glue joint it isn’t going to hold in that area anyway.

-- Life is good.

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A Slice of Wood Workshop

886 posts in 1768 days


#3 posted 1105 days ago

Thank you all for the confirmation of what I didn’t want to do, haha. FYI it is from pine right at the glue joint. It also is right on the very outside 2 boards, so maybe it won’t be that bad.

Just for further questioning, what causes this? Did I use the wood too soon? Did sanding just reopen the spot for the sap to come through?

Is there anything that can prevent this?

-- Tim- http://www.asliceofwoodworkshop.com; Twitter-@asliceofwood; Facebook-http://www.facebook.com/asliceofwood

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ajosephg

1839 posts in 2156 days


#4 posted 1105 days ago

I avoid it by not using pine. Poplar is inexpensive and finishes better than pine.

-- Joe

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A Slice of Wood Workshop

886 posts in 1768 days


#5 posted 1105 days ago

@joe- True. It is inexpensive and finishes better, but my wood was free from a pallet. I was trying to “recycle” it. It looks great, except for like a little dab of sap the seems to come out when it is really hot/humid (living in central NC).

-- Tim- http://www.asliceofwoodworkshop.com; Twitter-@asliceofwood; Facebook-http://www.facebook.com/asliceofwood

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ajosephg

1839 posts in 2156 days


#6 posted 1105 days ago

I just happened to remember something. High temp kiln drying “sets” the sap. If your wood came from a pallet, it is highly likely that it was never kiln dried, and it continues to bleed.

Your only solution might be to let it set a while after cutting and sanding to see what happens. Might be good to put it outside in the sun and accelerate the process. If any sap rears its ugly head, cut it out and keep on trucking.

-- Joe

View DLCW's profile

DLCW

522 posts in 1249 days


#7 posted 1104 days ago

After staining, seal the pine with about 3 coats of 2lbs cut shellac. This will seal the sap in. Once dry, apply your clear coat.

-- Don, Diamond Lake Custom Woodworks - http://www.dlwoodworks.com - "If you make something idiot proof, all they do is make a better idiot"

View oblowme's profile

oblowme

91 posts in 1158 days


#8 posted 1102 days ago

I use a simple but effective method for sealing knots- In the process of sanding a piece I pack the knots with a mix of stainable glue and fine wood dust, best if from the same species. You want just enough glue to hold it together and might want to cut it with a little water at first. You have to mix it up and let it set in an open container an hour or so until the dust absorbes all the water it can, adding a SMALL amount of water will speed up the process but you have to be careful as too much will weaken the glue.
If it ends up too thin add a little more glue/dust. If too thick add more glue/water but be careful with latter.
Press it into the knots, let it set 20-30 minutes and sand, apply again change grits and sand and so forth.
I discovered this by pure luck- I had a large pine table top kinda thing in the shop and never had much success sealing knots as they apparently have an unlimited storage capacity, that and they usually have several open checks and/or splits. Just for the hell of it I tried this and it worked out very well for me.

-- A TOOL JUNKIE- There, I just admited it to myself...

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