Painting MDF cabinet

Hi everybody,
I'm new to woodworking and new to this forum, so I might need more explanation on some things.
I have several cabinet made by someone else that I'm going to paint. Try to make it very glossy. Laminate is not an option since I just don't have the budget.
From what I gather after some research, I need to :

- seal the edges and sand after dry. Any suggestion what should I use to seal?
- prime the MDF. Some site suggest solvent based is better compared to water based. Any suggestion what primer? Also, how should I apply the primer? brush or spray?
- paint a few coats with sanding in between. What type of sandpaper should I use? Also wet sanding was mentioned somewhere. What exactly is it and why?

Sorry if I have so many questions. I appreciate any advice. Thanks.

If you've got access to a compressor and spray gun...go to Supercheap Auto and get car body stuff. Spray primer surfacer to do the 'grain' filling on exposed edges and acrylic lacquer for your top coat. (Or spray cans of the stuff if you don't have a compressor!)

Technique wise, see the 'custom spray mods' channel on youtube - Custom Spray Mods - YouTube and imagine your MDF is a car! (But don't break out the wet sanding till you are at a final coat...stick with dry sanding).

For the type of sandpaper - I rather like the no-fill (white coloured, typically) stuff for hand sanding on wood; otherwise, whatever fits my ROS.

Wet sanding can refer to:
Using wet n' dry sandpaper with water to sand something (the water washes away residue so the sandpaper cuts better/faster)
OR
Using wet n' dry sandpaper with an oil finish (that's oil as in tung oil, not oil as in oil based paint) to work the fine sanding dust back into the grain so it works as a grain filling agent. Typically done with a messy slurry of oil+sanding dust, hence the term 'wet'. Not recommended for MDF!

For wet (water) sanding on MDF...you need to make sure that you don't hit bare MDF, otherwise there's a very good chance of it swelling.

The professionals who did our kitchen cabinets simply used spakfiler to fill the edges. Quick to dry and easy to sand.

Cheers
Arron

Thanks for the tips...

Plaster board jointing top coat is also good for filling and smoothing the grain on MDF, quick drying and leaves a surface as smooth as the face with a light sand.

Remember to wear a dust mask when sanding MDF, the dust is not good for you.

Wood filler like Timbermate diluted with water makes for a good sealer I've found.

Thanks guys. In the end I used wood filler. As for the primer, how many coats should I do it? Will one coat do?