Not sure where you saw that info but, it should be somewhere in this thread.
Anyway, the best way to stop wood from blotching when staining is to coat it with shellac first. The way I do it is use a one pound cut of shellac, let it dry, lightly sand it with a very fine grit of sand paper (220 grit or higher) to knock down the fuzzies then stain and finish to suit your self.
The shellac you buy in the quart cans in the store is a 2# cut. In order to get a 1# cut is to mix some shellac with an equal amount of denatured alcohol and brush it on. (I use a foam brush usually)
It drys fairly fast, depending on the temp. and humidity, usually 15 minutes or so and fills the pores of the wood so it doesn't soak up the stain in different areas of the wood more than other areas.
Hope that helps.
Rog
