Replies

1. 
   hammer1 | Mar 01, 2006 08:33am | #1

   Shellac is the best sealant for blocking things like sap and stains but, sap will find it's way out. You must have used some construction grade lumber that wasn't dry. Now that it is in the house, the wood thinks it's Spring. Some pine can bleed forever but it is more prevalent in pitch pockets and knots. Did you notice that the surface was sticky when you built the piece? Sappy pine would have loaded up your sandpaper quickly and your hands would be stained. The surface would be grainy feeling due to all the beads of dried sap. If the lumber was like this, it will slow down over time but it won't completely stop anytime soon. It will wipe up with a clean rag and just a touch of mineral spirits. If this doesn't clean it up, there is another problem.

   Since you describe the problem starting with the first coat of shellac, could this be the issue? Did you wipe down the boards with anything, have fresh shellac or add anything to it? Alcohol doesn't activate sap like mineral spirits would. I think you just made a bad choice in lumber.

   Beat it to fit / Paint it to match

1. 
   Masrol | Mar 01, 2006 11:07am | #2

   Hi hammer1,

   Thanks for your opinion.

   For your info , the surface was very clean and well surfaced (S4S).

   I bought the stock  from a very renown  D.I.Y store. The  8" X 36" X 3/4" board was nicely wrapped separately for each board with transparent plastic wrapper.  I did notice there are about three saps on  that  particular board.  All the saps  are through on both sides of the board.

   What I wonder is why  the  problem  happens  to  one sap  only and  not to the other two.  I did not  wipe  the board with anything before applying the shellac.  And I used  premixed shellac without any additive.  My 1st intention is to put lacquer as the final top coating  to  enlighten  the shine. But  I am afraid  it  may  become worse. I hope  that  liquid  will not  cause any harm  since  that newly built rack  is right in the cooking area.

   Masrol,

   KUL, MY

    

    

    

    

    

    

1. 
   JohnWW | Mar 01, 2006 07:15pm | #3

   You are probably dealing with pitch, also called resin, in the wood.  Being organic, some pine has much more pitch in it than the average board. 

   Kiln drying will typically harden the pitch in the wood, but a board with larger pockets of pitch can still weep pitch even after being kiln dried.  As the first poster suggested, there is no good treatment for this, the wood will possibly leak small beads of the resin for many years.  The beads usually appear in hot weather and will typically harden on the surface in a few days, after which they can be lightly scraped off with a cabinet scraper.

   I have a pine chest that's fifteen years old that still has beads appear on its surface every summer.  The best way to deal with this is to give the piece an oil finish that can be lightly scraped and touched up with a wipe of oil as needed.  Shellac will seal some pitch in, but isn't effective with actively weeping wood.

   John White, Shop Manager, Fine Woodworking Magazine