/Pine - Sealing the end grain of the wood is a good idea. Also, bark side out keeps the board from cupping and holding water.
Some background on this:
I do some wood turning and need to let the wood dry evenly before turning to prevent warping and splitting after it is turned. The end grain lets out moisture in the wood faster than the side grain, so we try to keep the moisture evaporation even to prevent splitting, etc.
When the wood is dry you want to do the opposite, that is, keep moisture from being sucked into the end grain. What I do to the end grain of the wood is dip about a half inch of the wood into an old electric fry pan about half full of old candle stubs. I heat the candle wax to about 250 to 300 degrees. I do this outside. When the wax is all melted and almost smoking, I dip the wood in about a half inch. I hold it there a while until it starts to bubble or hiss. This insures that the wax has been sucked into the capillaries of the end grain. As the wood dries I can see the wax squeezed out of the shrinking end grain and this tells me that the wax has penetrated the wood and it will keep out the moisture.
Be careful of the hot wax. If it get too hot it can flash into flames, that's why I do it outside.
I have tried to brush hot wax onto the wood and found the the cool wood just holds the wax onto the surface and if hit or rubbed, the wax just falls off. That's where holding the wood in the hot wax heats up the wood and the wax and wood sort of "fuse" together to make a good moisture barrier.
HTH
Clem