Learning to "back down" your finish is paramount. Once you have a surface finish built up on your stock. It needs to be sanded in order to level out the finish . As the finish seals the stock it begins to pool in the pores and they do fill to a degree. However, you are still adding material to the surface of the stock thus creating high points (the stock surface) and low points (the pores). One quick way to level this all out is to sand between every few coat. Try sanding with a 800-1000 grit wet/dry paper lubricated with 2/3 linseed oil 1/3 mineral spirits.
Without the lube you will pull the finish form the pores and clog the paper. If you sand to heavily you will pull the finish form the pores. It takes a lot of practice to know how much to sand between coats and how many coats of finish between sanding. However, it is always better to sand to lightly than to much.
Do some experimenting with this process and it will all come together.
Dan
