EXT wrote:

If your wood was cut with a proper saw blade and/or sanded properly
there should be no need nor any way you can use wood filler on end
grain. The wood itself should be smooth not some filler stuck to it. Do
it right the first time and it will work properly.


Without knowing what look the OP is after, he certainly may need a
sealer on end grain.

Even if I finish pine end grain with a sharp low angle block plane, raw,
unsealed end grain will definitely telegraph through paint.