Wilfy, I'm at the same stage as you regards painting an mdf product.

Sorry I don't know the answer to the above question but on my project, I've decided to go with the flocked foam rollers I linked in your earlier thread. I'm using standard water based acrylic primer, 1 coat on edges first, then 2 coats all over with sanding inbetween. For the top coats I've decided to use plain old non drip gloss with the same rollers, 2 stretched out coats with light sanding. I've started priming and sanding and soon should have paint on something so you could see the finish I get and maybe follow. If the gloss flattens out as I hope I should get a nice flat shiny finish, as the prep work will be of high quality.

Cheers Adil