There are two critical steps in prepping kitchen walls.
Clean and degloss
Cleaning is critical: TSP or TSP substitute.
Deglossing: either light sanding (120 grit) or a chemical deglosser
Once a surface is deglossed, it should be primed, especially if going from one paint type to another.
A deglossed oil undercoat can be primed with a latex primer. Either oil or latex can then be used as a topcoat.
A deglossed oil undercoat can be primed with a oil primer. Either oil or latex can then be used as a topcoat.
It is better to stick within families of paint types, if you can, but going back and forth between types is possible with primers.
At this stage in coating, I'd let everything dry for a week, then sand lightly. If the previous layers are adhering, then proceed with latex primer, latex topcoat.
If,, however, they are sloughing or chipping or you can easily pull a layer off if you leave painters tape on overnight (and then pull it off), then you must sand down to the last well adhered layer and then repaint. Good luck.
If you select boards with knots, there is a good chance that they will bleed through, even if you use a sealer or shellac based primer. The resins in knots is persistent.
Clear boards are usually used for moldings, including baseboards. You could also use MDF (medium density fiberboard) or solid vinyl composite molding. When painted, they are hard to distinguish from wood in most applications. (I think they look a little too smooth and I prefer wood). For painted applications, there is also fingerjoint molding, which is made of interlocked short pieces and is cheaper than clear boards. Much pre-primed molding is fingerjoint. Occasionally these joints may show if the quality is not high.
For wood or MDF, a light sanding with 120 grit paper is recommended to remove milling glaze and to give the wood a tooth to better take paint. An orbital sander is fine
Then prime and paint. Many prefer oil based primer on raw wood and MDF. Some vinyl says it can be painted directly, but I would also give it a sanding (or avoid it unless necessary, such as in outdoor uses).
Latex paint is fine for a finish coat, but it tends to look less smooth than oil (alkyd) based finishes. Adding a leveling agent like Floetrol helps, but nothing lays as smooth as a good oil based enamel.
(P.S. To me, using a really smooth straight clear board, in furniture or in molding, is appreciating and honoring the wood, the tree, nature. But to each his/her own.)
Best Answer
Sounds like you're going to have to complicated-ly scrape those stars off! Seriously, though, you're right: it would take a fair amount of paint to stop the glowing, and even more paint to build up enough height to bury the stars completely.
The paint entombing the stars is most likely to be of the latex variety. This stuff is somewhat stretchy and rubbery, so to minimize peeling the paint away from the ceiling it'll be important to cut the paint around the star. Use a small and sharp hobby/craft knife to trace the outline of every star. Use light pressure -- you only need to cut through the paint film that's actually over the star, and it'll really be best if you can avoid damaging the paper facing of the drywall behind all the layers of paint.
With the perimeter of the stars cut free the next step is to lift them off the surface. You'll need some kind of prying tool. If the stars are just thin stickers then the knife itself may be adequate. If the stars are the thicker rigid plastic type then another tool may be better: a chisel, a putty knife, or some kind of scraping tool.
After the stars are gone you may want to make repairs. If the over-coat paint was thin and if the stars peeled away nicely then you might get away with just another coat of paint. On the other hand, if there's much of a step in the paint film or if there's damage to the underlying surface then you may need to use a filler like drywall joint compound or topping to smooth things. As in all drywall repair if you use a filler then you'll need to also use a primer before progressing to the new finish coat.