Hmm...

The problem I have with BLO (Boiled Linseed Oil) is like all of the
other oil based finishes I have tried it imparts a very yellow hue to
the wood. While I find this perfectly acceptable on darker woods like
walnut and Ipe (even desireable) it is way to yellow for me on lighter
woods like maple. Some people may find the yellowish hue perfectly
acceptable on lighter wood. If I were going to put a base coat of BLO
on a project I would probabally just use an oil based varnish with it
(1/3 tung or BLO, 1/3 spar varnish, 1/3 turpentine, wait... wait...
wait for it to dry).

I have never tried a base or seal coat of clear shelac under poly for
"popping the grain". I have only used shelac under stain to try to
even the stain out. This might be worth trying on some test wood. I
find water based poly a little lifeless on maple and laquer not much
better. A little "pop" would be nice if it didn't impart any color.

Thanks for the tip!