Another possibility.

Do It Right the First Time: What Every Homeowner Needs to Know ... - Google Books Result
by Gene Hamilton - 2005 - House & Home - 209 pages
This product will equalize the absorbency over the entire wallboard surface, so the face paper and taping compound will absorb paint equally. ...
books.google.com/books?isbn=0974937355...

A high-performance water-based coating system. Background ...
Application: Opaque prinmr + finishing coat - 110 la dry .... wood deteriorating and discolouring fungi,. Equalizes absorbency of wooden surfaces, ...
www.springerlink.com/index/DM65480074603786.pdf

After properly sanding the wood, it should be conditioned to accept the water-based stain. Conditioning evens the absorbency, resulting in a more uniform stain. Grain-raising is only done once, and although it can be accomplished with just water, water alone does not help to even out the porosity of the wood. Traditionally, conditioning is achieved with a “spit coat” of dilute shellac or lacquer

http://www.goldenpaints.com/technicaldata/woodstain.php

As a softwood, pine does not absorb wood stain evenly. Simply applying a stain with no preparation may result in a "blotchy" appearance with contrasting dark and light areas. Applying the wood conditioner equalizes the absorbency of the pine so that a more even finish is obtained. Follow the directions on the can regarding proper application of this product.
http://www.naturalhandyman.com/qa/qawoodfinishing.html

Wood sealer is used on soft woods to help tame wild grain patterns and even-out stain absorbency. The sealer penetrates the wood, slowing stain absorbency for a more even color appearance and grain pattern.

http://paint-and-supplies.hardwarestore.com/learning/all-abo...

Rhenocryl TL 30 wirkt egalisierend, verringert die Fleckenbildungsgefahr.

http://www.rhenocoll.de/products/de_hfht_propx.html