Hi All, I've finished off half of a new office for the wife using MDF and have suddenly figured that I'm not sure that emulsion will take to the MDF. Anyone got any tips, mixing pva with the paint seems to ring a bell
If you have a branch of Brewers nearby nip down and get a tin of their acrylic primer undercoat. I use it all the time on MDF, a couple of coats (I use a 4" roller fitted with a short haired emulsion sleeve) followed by a quick rubdown with 180 grit and you're ready to rock'n'roll with any old topcoat you like. Wonderful stuff, touch dry in about 20 mins and tough as old boots after about 4 hours. Just don't stack painted pieces on top of each other for a couple of days or they'll weld themselves together.
A technique I use to cope with edges may not work so well if the piece is already fitted; most of my stuff is made as "knock-down", carcases for built in wardrobes etc., so it gets primed in the workshop as individual, usually flat components. Anyway, the "grain" on the edges tends to lift quite a lot with any water based product and consequently become very rough. No problem, I just coat each edge every time I do one face so they end up with twice as many coats. The acrylic builds nicely and can be rubbed back to a lovely smooth finish ready for the topcoat. Just make sure to "ease" all sharp edges before you begin, and be careful not to rub right through the primer, otherwise it will be difficult to get a smart edge if it is a square edged piece.
I've had similar success using pva 1/1 with water but it adds so much labour to the process because you have to do the edges twice with all the drying time etc. before you can even start to prime. I just can't justify the extra time on a paying job that I've probably underpriced anyway.
Hope this helps.