prepairing MDF for painting

SplanK

This weekend we have been decorating our hallway and landing... almost there and finally got around to boarding up some crappy hallway to loung gastly windows up with 3mm MDF

looks great - so i got on with the painting.... and it started soaking onto the MDF... so i popped some more paint on... same thing again.... only done 3 out of 12 pannels so far and the 3 that i have done look a bit pants...

is there a way to prepare the MDF for painting (im using gloss paint) or is it just a case of keep painting until it stops lol?? i was thinking maybe white matt paint (already have a large amount of it for doing the hall/landing) and then painting with gloss once dry

also since ive starting painting 3 of them - would i still use the same procedure on those and then paint over...?

misgrace

You havent put gloss straight on MDF, have you? :eek:

Are you using waterbased paint or oilbased?

I have painted so much MDF over the years I am sick of it lol, but if you let me know what your using, I can give you the proper advice.:D

SplanK

yep painted straight onto MDF.....

anyway - im not quite sure... i know its Dulux Trade High Gloss Brilliant white paint... - cant see anywhere on the tin to say either water or oil based?!

SplanK

actually - looking at the datasheet.....

Dulux Trade High Gloss Finish is a solvent-based finish suitable for the protection and
decoration of most interior and exterior surfaces where a durable high gloss finish is
required.

Before preparing

misgrace

Hi splank, the good news is that you have only done 3 panels the bad news is that you have a fair bit of work to do with the rest.:sad:

What you need to do is to get some oilbased/solvent Undercoat and a bottle of white spirit.

Pour some UC into a container or paint kettle, add some white spirit, stir well, and have the mix thinnish, dont use the UC straight from the can.
You want it thinned, but not runny, as the MDF will suck all the paint, and if its too thick, you will labour, get brush marks, thick bits, and your hands will ache like hell.
The first coat of thinned UC is like a mistcoat, it has to seal the MDF ready for your proper coats.
Always paint the panels first, checking any runs that might appear in the corners, then you can do your flat bits.

When dry, lightly sand, the face, but your beading and edges are always more rough than the flat bits, so you need to spend a bit more time sanding these areas.

For your second coat of UC, still add some white spirit, but half this time, stir again, and paint.
Then do your normal sanding etc, you will need to do a third coat, but you can go thicker with the UC, but personally I would still add some WS,( makes life a lot easier).

Then step back and see if you can get away with the gloss on top.

Usually when I do MDF, I would UC 4 times, then gloss, you get a brilliant finish, if I was using satinwood, or eggshell as a top coat, then I would UC 3 times, then do 2 satinwood or eggshell.

There is MDF primer out there, but to be honest, you would need a fair bit, and its not cheap, but you would still have to UC a couple times anyway, so your better off IMO with the UC then your gloss.

Also, when you do gloss, just add a smidgeon of WS, again, it will go on smoother, plus a better finish.

Hope this helps.:D

SplanK

thanks - you have just filled every night of next week with painting work lol
would it be worth starting again with the 3 pannels ive already done or just start with UC'ing it??

misgrace

Personally I would rub down the gloss panels, and just give them 1 UC, as you say they look pants anyway lol.
Undercoat works as a base to take the gloss, the gloss is translucent, where its got no guts so to speak, so your better off UC the 3 panels, then gloss them.

SplanK

thanks for advice will nip to a diy store tomorrow...

what UC do you use? might as well use a tried and tested one

misgrace

You cant beat Dulux, thats what I normally use, but if you are near a Dulux decorating centre, you will be able to buy 'Gliddens' paints, its made by Dulux, but originally for the American market.
Its a fair bit cheaper, very high quality, goes a long way, and IMO excellent.
'Gliddens' come in UC, gloss, satinwood, emulsion etc, and you wont go wrong using it.
Usally if you pay cash at the Dulux dec centre, they will give you 10% off, plus they give nectar points lol.