Anyone who ever tried to paint (any kind of paint) over urethane or varnish as a kid knows it doesn’t work. If you ever tried to paint wood without a hefty few layers of sandable primer, you have seen the same thing.
Wood grain has differing densities, and you can’t sand it smooth enough to paint – without seeing said grain.
When it comes to painting kitchen cabinets, you have both of these problems.
There are at least three ways to paint wood grain cabinets that have been stained/sealed. They all require deglosser, to basically remove and neutralize the varnish and/or stain on the wood.
The first method involves using wood filler or plastic wood. Muralo Spackle Paste is recommended. Here’s another well-researched page that discusses using a wood filler.
The next step would be sanding, and eventually priming. Finally the cabinet paint. For that, if you do your preparation properly, you have a variety of options.
The second method is skipping the wood filler and applying many layers of sandable primer. This is a labor-intensive and slow method.
The last method involves using a store-bought cabinet makeover for removing the wood grain and recoloring. Essentially a bond layer and a final layer. These cost about $75 each. And the results appear to be promising.