WEAR GLOVES, I prefer the chemical resistant variety, and DO NOT breathe the vapors(!!!!) when mixing lye with water. ALWAYS put lye in water, and then stir until its disolved. Its best to do this outdoors.
ONE tablespoon of lye in 8oz of water is plenty strong. Apply it liberally and watch the color change, but it will dry to a lighter color. If you DON'T blush it with heat, it can be a deep red. In that the lye (base) reacts with the tannic acid in the wood, it will react until there is no more acid or base to react with. Rinsing with water is recommended, vinegar (acid) would be optional, but that would need to be rinsed with water as well.
I did a block to show someone, applied Minwax Tung Oil when it was dry, and it hasn't changed color in the more than a year that has passed.
I make soap so have a good supply of NaOH on hand. Look for lye at your hardware store if they still sell it. Red Devil was the last that I bought locally. It may not be easy to find since the meth cookers use it....