You are faced with end grain splitting or tearing out when working some woods. Most woodworkers know to clamp a piece of waste stock hard up against the material being worked to prevent this when planing across end grain. But what about those times when you are simply sanding or doing some other operation on end grain?
Some materials have a bad tendency to tear out slivers at the ends of narrow stock, such as a chair or table leg. Sometimes simply sliding a wooden chair leg across the floor – especially if the floor is textured, can tear out a sliver or wood at the end grain. Maple is bad for this, as are some pines, and mahogany.
A simple little trick I have found is this: Turn your stock so that the end grain is up; using masking or duct tape, make a tape ‘dam’ completely around your stock – see photo below:
Mix a little good quality varnish with a bit of thinner so that it is quite thin. Pour or brush a little of this on the end grain inside the dam. Be sure to get enough there so that it ‘floats’ or stays liquid on top of the end grain at first. Leave it to soak overnight or longer, until it is completely absorbed. Most woods will soak up liquid by capillary action, quite far into the wood – sometimes several inches. You can see the evidence of this sometimes when it weeps out the sides of the material below the end grain and dam. See Photos:
Of course you can do something similar with glues, but they are usually of such a viscosity glues, even thinned, will not as easily soak in as a paint or varnish. Once the material is soaked in, remove the tape, clean up the sides and allow it to cure until hard, which may take a day or two.This will bind the fibers together and usually will cure problems with end grain tear out.
-- "Never let your dogma get run over by your karma!"