I'll bet you're brushing that sealer right from the can? The real trick to finishing with any sealer is to thin it way down for the first coat (at least 50/50 maybe more depending on the sealer). Called a wash coat by many and used for many things including blotch control, it will also eliminate bubbling in porous woods. As Cabinetman said a paste filler is the answer to filling your grain.
I like Sherwin Williams grain filler because you thin it with VM&P Naptha and it dries in just 4 hours. I also like to stain first and then apply a wash coat of sealer before applying my paste filler (With a dark colored stain the filler will need to be tinted to the color you wish your grain to be). This prevents a disaster called gray pore which can occur when paste filler is applied to raw wood. The other advantage is the filler wipes off MUCH easier when applied over a wash coat of sealer, you can even use a squeegee to take it off very clean and fast.
On oak to get a closed pore finish you will probably have to do 2 applications of filler. (Do not seal between coats of filler) On some brands of filler you will need to sand between coats with Sherwin Williams you do not sand so you must wipe the filler off really clean.
Once the filler has dried apply a full coat of sealer, let dry, scuff sand with 320 grit 3M tri mite sandpaper and then begin applying full coats of whatever your top coat finish will be (the build coats should be gloss if your final coat will be satin wait until the final coat to apply it). After each coat dries sand with the 320 sandpaper dry using a sanding block so that you level the surface, being VERY careful not to burn through the finish to the sealer or raw wood.
After you have applied enough coats that there are no shiny areas in the grain after sanding you are ready for your final coat. When that dries you can either leave it as is, rub it out or buff it to a high gloss depending on the look you are after. You are on the right track by making samples before you start on your project. I would continue to do so.
Last edited by Rick Mosher; 11-26-2010 at 09:34 PM.