Painting mdf
- Thread starter phil2010
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mailee
Established Member
It really depends on what sort of finish you want. I generally spray MDf with AC laquer for the best finish although I have hand painted it with dulux gloss before. Firstly you need to seal the MDF with sanding sealer or one of the MDF sealers paying particular attention to the edges. I should add that it is far better to use Moisture resistant MDF rather than the usual MDF you get from the likes of B&Q. When ths sealer is dry use something like 320 grit paper to rub it down. Next use a primer again for MDF or one formulated for the top coat you are to use. Once this is dry rub it down with something in the region of 400 grit. Then on with the top coats. If it is a sprayed AC laquer this is usually two coats for me. If it is a brushed gloss thenone or maybe two coats depending on coverage/brush marks, etc. I find that gloss an oil based paint is best applied by a small sponge roller which will leave no brush marks but will give a light mottled effect. HTH. :wink:
mailee
Established Member
If you are going to spray finish it then yes I would use wet n dry paper on the final coats. You can use from 400 up to 800 if necessary. Also with AC laquer you can nib out any marks with 1000 and above wet n dry and then polish the final glaze to a very high sheen. I would only use dry paper on the sealer and primer coats though
TheTiddles
Established Member
I was just about to ask a question about this myself.
I've probably done around 30, 8x4 sheets worth with this technique so far.
For the edges, cut back with 120 or 180 and a block then ease the edges, the rest of the face, straight on with quick-drying woodprimer (ScrewFix) or MDF primer (Toolstation), normaly I apply two coats of this with a gloss roller, then 'rub' back with 120 grit on an orbital sander till it feels smooth, except the edges which I do my hand. From there, Leyland oilbased eggshell, ideally three coats with the same cut back inbetween but two can get you through, again with a gloss mini-roller.
The finish is well, eggshell, not matt and not gloss, quite a pleasing in-between which isn't amazing, but it's plenty good enough for me and I'm the first to pick holes in things.
My reasons for this technique are based on a few things:
1) It's cheap, primer is about £5/litre and top coat is £6/litre.
2) Mini-rollers can be wrapped in a bag after use till the next round of coats, I'll use two rollers for an entire build normally, one primer and one gloss.
3) Spray kit is expensive, but I'd gladly buy it, if I thought that a spray booth would be anything less than a total pain in the buttocks given I have a packed single garage and a bit of driveway to work in.
4) You can touch-up when all assembled with a roller again quite easily.
However, this is the root of my question, the gloss has a 24hr dry which is a total pain given how fast you can work with MDF, the primer is touch dry in 30mins normally and you can overcoat in an hour or two. What can I use as an alternative to the oilbased eggshell?
My normal practice is to fill the garage with panels at the end of the day, work from back to front painting as I go then shut the door leaving them. However, 10pm to 9am the next day isn't 24hrs and the paint's still not dry the next day if I am able to work on it then, such as at the weekend. Any ideas?
Aidan
I've probably done around 30, 8x4 sheets worth with this technique so far.
For the edges, cut back with 120 or 180 and a block then ease the edges, the rest of the face, straight on with quick-drying woodprimer (ScrewFix) or MDF primer (Toolstation), normaly I apply two coats of this with a gloss roller, then 'rub' back with 120 grit on an orbital sander till it feels smooth, except the edges which I do my hand. From there, Leyland oilbased eggshell, ideally three coats with the same cut back inbetween but two can get you through, again with a gloss mini-roller.
The finish is well, eggshell, not matt and not gloss, quite a pleasing in-between which isn't amazing, but it's plenty good enough for me and I'm the first to pick holes in things.
My reasons for this technique are based on a few things:
1) It's cheap, primer is about £5/litre and top coat is £6/litre.
2) Mini-rollers can be wrapped in a bag after use till the next round of coats, I'll use two rollers for an entire build normally, one primer and one gloss.
3) Spray kit is expensive, but I'd gladly buy it, if I thought that a spray booth would be anything less than a total pain in the buttocks given I have a packed single garage and a bit of driveway to work in.
4) You can touch-up when all assembled with a roller again quite easily.
However, this is the root of my question, the gloss has a 24hr dry which is a total pain given how fast you can work with MDF, the primer is touch dry in 30mins normally and you can overcoat in an hour or two. What can I use as an alternative to the oilbased eggshell?
My normal practice is to fill the garage with panels at the end of the day, work from back to front painting as I go then shut the door leaving them. However, 10pm to 9am the next day isn't 24hrs and the paint's still not dry the next day if I am able to work on it then, such as at the weekend. Any ideas?
Aidan
Thanks,i didnt know that you could keep coating with eggshell,i thought it would be primer 1 coat, under coat 1 coat then eggshell or gloss 1 coat.What about primer undercoat then a clear varnish, does it come out a good finish.
TheTiddles
Established Member
I should make some test plaques some time, might be a usefull exercise...
Primer then varnish I suspect would look absolutely terrible.
Aidan
Primer then varnish I suspect would look absolutely terrible.
Aidan
mailee
Established Member
As far as I know Aiden only AC laquer will dry that quick. I know of nothing as quick drying as that that is applied by hand.
lemonjeff
Established Member
Aidan,
I've never tried it but I'm told it gives a good finish.
https://vault2.secured-url.com/frenchpo ... quers.html
If you look halfway down the page there's A/C brushing thinners (and rollering?).
Although A/C paint doesn't tick No1 on your list it could be a solution to your question.
Jeff
I've never tried it but I'm told it gives a good finish.
https://vault2.secured-url.com/frenchpo ... quers.html
If you look halfway down the page there's A/C brushing thinners (and rollering?).
Although A/C paint doesn't tick No1 on your list it could be a solution to your question.
Jeff
studders
Established Member
xy mosian
Established Member
This is a very interesting topic, especially as we are now talking hand applied finishes. A good friend of mine, professional painter and decorator, uses sealer, emulsion and then water based top coat, often gloss for kitchen work. He uses this technique for new build as well as existing. Part of his reasoning is that he can paint kitchen doors etc., in situ, the smells and long drying times associated with other methods are sometimes a trouble.
HTH
xy
edit, after re-reading. The water based top coat he uses is laquer/varnish, that is more or less transparent.
xy
HTH
xy
edit, after re-reading. The water based top coat he uses is laquer/varnish, that is more or less transparent.
xy
As a painter and decorator what I use is two coats of Zinsser BIN which is a white shellac based product, which is dry enough to apply two coats within two hours then apply a top coat as required. You can have all three coats on in one day and dry next day if you use a water based top coat, which won't damage the mdf because you have already sealed it. Most paint trade centres keep the Zinsser range I tend to use the Crown centres but I hev seen it in a B&Q as well. Should cost you around £30.00 per gallon.
Thomson0
Thomson0
petermillard
Established Member
Thomson0":1hgjlf7u said:
:shock: Where are you buying it for that price?? I pay about £15/litre from my local trade supplier! Great stuff, I agree (much prefer it to 123) though when I'm painting MDF I often just use a quick-drying acrylic primer/undercoat (Leyland/Johnstones/Wickes) with an extra coat & a rub down on the cut edges.
I've used water-based eggshell as the topcoat both sprayed and with a 4" foam roller with good results - a bit more 'bobbly' with the foam roller, obviously, but not unattractive. I'm a big fan of quick-drying water-based paints - using Crown QD gloss at the moment, and it's very nice.
HTH cheers, Pete.
