New To Painting MDF

[nedley09]

So i am going to start painting my Cab tonight and was wondering if i could get some tips on painting MDF.

I read that water based paints is a no no.  Thats about all i know

I have 3D Vinyl, but i am having a hard time with it and though id just rather paint it.

Any suggestions on what kind of paint to use?

[Nephasth]

I used latex paint on a doll house I built out of MDF for my daughter. The MDF soaked the first coat up like a sponge. I did almost 3 coats on the whole thing. Some areas were 2 coats of latex, 1 coat of acrylic.

[nedley09]

how did it look?  was it bad?  I am trying to stay away from that lol

[sharpfork]

I personally use a shellac or oil based primer on raw MDF I'm painting or putting vinyl on.  I sand it with fine paper and give it plenty of time to dry.  I like to topcoat with Sherwin Williams All Surface Enamel Satin (water based).  I cut it a bit with floetrol to make it lay out smoother and apply with a fine foam roller.  Floetrol is away different than thinning with water.  I sand between coats with fine paper.  I've tried wet sanding between coats with 400 and the results were very nice.
Oil based topcoats can be easier to get nice results with but I hate working with oil and don't like the often too shiny finish (for my taste).  I've talked with painter buddies who say oil has become less nice as California has forced the removal of all the "good" stuff.  Good for paint but stuff that is bad for people.

I tried experimenting with my HVLP to shoot the water based topcoat but it had to thin it too much.  I do sometimes use the HVLP to shoot the primer, sometimes I roll that too.

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[nedley09]

Thanks for the tips.  Now how do you sand it?  just one or two swipes in each area?  I dont want to make it look grainy in between coats.

[Nephasth]

how did it look?  was it bad?  I am trying to stay away from that lol

It turned out pretty good: http://forum.arcadecontrols.com/index.php/topic,129273.0.html

[shponglefan]

When I used to paint, I'd do the following:

1) Fill in any imperfections w/ putty and then sand as smooth as possible
2) couple coats of primer, sanding in between coats
3) Few coats of paint, sanding in between coats
4) top coat varnish and polish that car scratch 'n dent remover

For sanding, just use progressively finer grit sandpaper as you go.  Also, it probably goes without saying but multiple thin coats of primer or paint are way better than a single thick coat.  And don't worry if you strip off paint or primer down the prior layer when sanding; you can always apply another coat.  The point is to get it as smooth as possible.

Since then, I've switched to using laminate for my projects; so much faster and easier.  I'd recommend it over paint, imho.

[nedley09]

Thanks!  Someone recommended i use a gloss roller instead of a brush.

should i use a oil based primer with a latex based paint?  It sounds like it will be a better finish

[jennifer]

     A good grade of sealer will not only lock down the surface but will put a shine on the cab showing any imperfections before you paint, and should you find any let the sealer dry, and work that, this way your not wasting you color, I prefer a clear sealer, because as the years go by and your cab gets dings, the damage area wont have a grey bulls eye around it... Water based paints have made some improvements, not really the junk they once were, but interestingly enough, they are still covered with a solvent base topcoat for UV considerations and durability.

[nedley09]

well i was going to use kiltz (SP?) oil based primer and sealer then a latex high end paint.

Real question is, brush or roller

[jennifer]

   Roller... Or an airless sprayer.

[Drnick]

I am currently going through the hell that is a good paintjob at the moment.  First I sanded down the mdf, then I hit it up with couple of light coats of Enamel Primer, Then I sanded down to 240, sprayed, sanded down to 300, Filled in the pits and pinholes etc with some Iso 38/Bondo. I then sanded down again and sprayed primer and sanded down to 400. one last spray and hit with 600 Sandpaper.  I am now onto the Gloss Black spray, I figure I do the same as above, then wait about a week. Hit it with a Clear Lacquer and rinse/repeat the sanding spraying combo.  I am hoping to have a real good finish, as even though I am covering it with artwork I want to be happy in the knowledge that my paintwork is as good as I could make it.

Sorry for the ramble, I been on a bit of a drinking spree tonight. 

[jennifer]

    Careful Drnick, you are discussing spray techniques, and how to get a nice paintjob, The real question is...Brush or roller? I guess.

[monkey puzzle]

I would definately recommend using a fine roller. I used this for my cab and got very nice results (it was just a very cheap foam roller). I have painted other projects before using a brush but the brush strokes are visable in the final finish. Different people here are telling you different things, but I used a clear MDF sealer on the bare MDF, followed by a water based primer, followed by 2 coats of satin topcoat (sanding with a fine wet/dry paper between coats). I was very happy with the results and would do the same next time. If in doubt, ask at a specialist paint shop like I did.

Sorry, but the only good photo I could find of painted MDF was the one of my back panels.

[Ond]

I am currently going through the hell that is a good paintjob at the moment......

    

[RandyT]

Using a water based latex primer on MDF is not a problem.  Kilz is my preference.  It goes on thick, and that's what you want.  Otherwise, MDF will soak it right in .  At least two coats, sand between each.

For a finish coat, I used bright red Rustoleum enamel on my mini pac-style cabinet.  Rustoleum is easy paint to get, not too costly, and it leaves a very nice finish.  Takes a while to dry, though, so don't be in a hurry.  Definitely use a foam roller, or at least a very high quality short nap roller which won't leave the dreaded fuzz.  Every dollar you save on a cheap roller will cost you 5 in the time and aggravation trying to fix what it does to the job.  Foam rollers are good, but don't try using them on a second coat of enamel before the first is completely dry.  I've seen half cured paint yank chucks of foam out of these when they start to run dry.

[nedley09]

whelp i picked up some kilz oil based primer and sealer, some semi gloss latex paint and a 1/4 fine roller with refills.  Im going to start priming tonight, but should i also roll on the primer?

[RandyT]

It doesn't really matter for the primer, as you will be sanding it.  Of course, the better the finish, the less sanding you'll need to do to smooth it out, so it's up to you.

[Bender]

I used a clear MDF sealer on the bare MDF

Got a product name on the MDF sealer?
This might be the key
No matter what I use the fibers in the MDF swell up and make the first few coats a nightmare

[macattack]

Best stuff to use is the stain blockers like kiltz or can't think of the other brand, will post it once I get home. Does a great job of sealing mdf

[nedley09]

I used a clear MDF sealer on the bare MDF

Got a product name on the MDF sealer?
This might be the key
No matter what I use the fibers in the MDF swell up and make the first few coats a nightmare

I used kilz and it looks good so far.  All though i have not primed the whole cabinet yet.  I do not think i will be painting the bottom where the MB and PSU are going to stand.  I am still debating on painting the inside of the back, but im leaning toward yes

here is a link to my new thread showing off my cab.

http://forum.arcadecontrols.com/index.php/topic,130631.msg1337665.html#msg1337665

[Le Chuck]

I use rattle can primer.  If I'm only painting the paper side I'll use krylon and anything I put ontop of it goes like a dream.  If I'm doing anything sculptural I'll use spray putty and glazing compound to prep then start painting.  I think MDF is super user friendly as far as painting is concerned. 

[nedley09]

I think i made a boo-boo with paint.  i picked semi gloss latex and now my cab is sticky. 

What should i do to fix this?  Its black right now.

I was thinking i sand it down and get a different paint, but which one?

[Le Chuck]

If the paint is tacky it isn't fully cured. Let it cure. If youve already marred the finish let it cure before you rub it back to repaint. It may say 2O minutes on the can but it takes days to fully set.

[nedley09]

well poop, i already sanded it.  i cleaned it and everything.

i though latex is always tacky

[jennifer]

     Wipe it off with thinner rags and start over.

[nedley09]

so no on just painting over the sanded parts with an egg shell paint?

[Le Chuck]

I wouldn't topcoat a partially dry partially sanded latex paint with a different paint. Latex shouldn't be "sticky". It's the most common interior wall paint in America, are your walls sticky?  Since you already started sanding I'm with Jen, remove it all and start again.

The effect you're getting is called Blocking. It occurs when the paint isn't allowed to cure. At 75 degrees F the cure time for a thick coat of latex is weeks to a month. Other paints like enamels have much shorter cure times and are more durable but are also more expensive and can be trickier to work with. You can ask your paint store to add a curing agent to the latex paint to speed drying if that's how you decide to repaint.

I'd get the latex off and use an enamel.

[nedley09]

ya i was afraid of that.  My only issue is its 20 degrees outside and i am working in my basement.

The fumes from the thinner might cause problems for me, my wife and cats

[jennifer]

      Just push it over by the door , open a window, and get it off of there...You, wont get a get a decent finished result by topcoating a messed up base, If you wait to long you will have to use stripper and that is really stinky and considerably more caustic. Just soak a rag and wipe it on, good and wet and with the other hand wipe it off with a dry rag. Work the whole cab this way so no one spot stays saturated, just keep working around it till the paint reacts and falls off, It will take some time and alot of thinner and rags, then let dry and seal and paint again. ...The cats will hide, and your wife, Well, perhaps send her to the mall before you start...Jennifer loves the smell, Maybe she will too

[monkey puzzle]

I used a clear MDF sealer on the bare MDF

Got a product name on the MDF sealer?
This might be the key
No matter what I use the fibers in the MDF swell up and make the first few coats a nightmare

Sorry, I've been looking, but I can't find out what brand it was. It was few years ago, and I bought it from Brewsters paints (UK), but I've been looking on their website and can't find it there. I think there is other sealers available, but this one was specifically for MDF. It worked really well, I recommend looking for something like this.