# Painting MDF and got some brush marks...



## AAANDRRREW (Mar 11, 2015)

So I have put tons of effort into carefully building a beautiful fireplace surround out of MDF. I sanded it with 120 (RO sander), did a coat of zinnser bullseye primer, sanded again, another coat, sanded again then a coat of hallman lindsays aqua alkyd paint. I have done the process many a time on my oak trim and doors with good results. I use a good Purdy brush, move quickly and lightly backdrag the brush to flatten out the strokes and the paint usually self levels and life is good - not with this so far. I'm not sure if its the extreme smoothness and flatness that the MDF has that doesn't hide the strokes like the oak doors do or what.

So, at this juncture, I was going to sand it again with 120 and paint again, this time trying a different brush. Could it be that my primer and paint were purchased last september and have sat (sealed) 1/2 full since then? I'm paining in the house and it's been in the 70's outside, not real humid and even one day the AC was on…

Also, I have tried a foam roller on other projects, but it leaves a really small but rough texture (almost like a sandpaper feel) - can someone point me to a good roller (that say menards or home depot carries) that wouldn't leave as much texture? I'd like to get a small one because a fullsize roller won't fit between the face frame in certain places.

Really pissed and discouraged that after all the effort into making this perfect I have brush strokes like I do. Sanding is more difficult now too because the paint doesn't sand as nicely as the primer. My wife says it's fine and she can't hardly see them unelss she gets close, but she's just being nice and doesn't want to piss me off more. It does look fine until you get at the right angle and sun is shining in the window and the marks are clearly visible…


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## GR8HUNTER (Jun 13, 2016)

try this method : 



GOOD LUCK :<))


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## Nubsnstubs (Aug 30, 2013)

Andrew, if your wife is happy with it, leave it alone. Quit obsessing about something you won't even notice in 6 months.

Have you watched the Hillbilly video. Heck, he hasn't even puttied the nail holes and the seam between the face frame and carcass, and he's proud of his paint job. Otherwise, he wouldn't have posted his video…...... Jerry (in Tucson)


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## hotbyte (Apr 3, 2010)

You could try a little Floetrol to see if it let brush strokes level out better. I used some in an Ace brand waterborne alkyd at it worked well. I wasn't sure if I should use Floetrol (water based additive) or Penetrol (oil based additive). Since instructions said thin with water, I went with Floetrol.


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## AAANDRRREW (Mar 11, 2015)

Nubstubs - easier said than done .... I will notice it in 6 mo and still get pissed haha.


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## GR8HUNTER (Jun 13, 2016)

we are most critical of our own work ….but HAPPY WIFE HAPPY LIFE :<))


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## rwe2156 (May 7, 2014)

> So I have put tons of effort into carefully building a beautiful fireplace surround out of MDF.


MDF is a PITA in many ways, especially painting. It needs to be sprayed to look good.

That being said, I have brush painted several steel doors with gloss oil paint and they look really good. I suspect the same would apply to MDF. I've always thought you aren't supposed to put oil on top of latex so I don't know what to tell you about that.


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## AAANDRRREW (Mar 11, 2015)

My primer and paint are both water based.

yes, MDF is a pita when it comes to dust and assembly, but I was told it paints up so nice. It is sure nice, flat, square and cheap.


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## pintodeluxe (Sep 12, 2010)

Spray it. Spraying is the only way to eliminate brush marks.

Especially if you are trying to brush vertical surfaces (as in the mantle is already installed). 
If it were laid flat in the shop, you might have a chance of the paint leveling out. But with vertical surfaces it's not going to happen I'm afraid.


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## dday (Jun 27, 2014)

"MDF is a PITA in many ways, especially painting. It needs to be sprayed to look good." 
+1 on this

It seems no matter how I prep or seal it, MDF absorbs paint quicker than I want it to and it looks streaky or shows brush strokes.

Spraying, even with a cheap gun from HF, leaves a smooth finish.


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## 01ntrain (Jun 21, 2015)

I always seal it first with an oil-based primer, it will swell with water-based…..then use the waterborne alkyd. But, yes it def is a PITA.


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## SignWave (Feb 2, 2010)

Although it's water based, I suspect that the enamel paint will sand decently if you wait for it to fully cure. I use the Sherwin Williams version of water-based enamel and it does harden enough to sand, much more so than a regular latex paint. Give it a week or two.

If you cannot get the surface to be horizontal while painting, then I agree that spraying is the way to get a smooth finish.


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## AAANDRRREW (Mar 11, 2015)

damnit. well, my buddy didn't tell me it was a PITA to brush or roll. That being said, spraying isn't an option because its installed already. I'm hoping I can sand it nicely and then maybe use a roller - I can deal with texture before I can stomach brush strokes.

Signwave - so, when I was sanding the primer it left little tiny BB balls, not dust. I figured it was because I was using too fine of paper or it was my vibrating sander instead of the RO sander - if I let it sit longer it will sand better? All the coats had a least 48 hrs to cure.


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## Kazooman (Jan 20, 2013)

The small foam roller will leave a texture as you said. The problem with that is that you cannot readily get the roller into corners and will have to cut those in with a brush. Texture in the field and smooth at the edges. That really stands out. Try it on some scrap before doing the entire mantle.

I was having a similar problem painting a set of shelves a while back and posted asking for help. The best suggestion was to use a foam brush. Try a GOOD quality foam brush, not the rock bottom cheapest from the big box store. I had much better results with one as compared to the high quality Purdy brush I had been using.


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## Nubsnstubs (Aug 30, 2013)

AAANDRRREW, hey man, next time you do something like this with mdf, why not get a laminate with the color and type of finish you desire, and build your project using those materials. You wouldn't have the finish issue you're currently having at this very moment and at least for the next 6 months. ............ Jerry Hahaha (in Tucson)


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## AAANDRRREW (Mar 11, 2015)

well, it would appear I will have to just embrace the brush strokes. Maybe I'll tell people its supposed to look like that (I can throw in words like patina and distressed…).

At any rate, I'll sand it tonight, try a different brush and maybe add a little floetrol to the paint and just live with it. Live and learn I guess.


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## GR8HUNTER (Jun 13, 2016)

next time use popular MDF IS OK but not my main go to :<)) GOOD LUCK :<))


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## Ragland (Jun 4, 2017)

I think they make a product like Penatrol (which is for oil based paints) that does the same thing except it's for latex based paints, It helps the paint flow and laydown smooth before it gets its skim top on it which will eliminate your brush strokes. Also you said you used a Purdy brush which is great as long as its not a china bristle brush, these aren't made for latex paint. You want a good nylon brush ! I'm miles away from being even a half ass painter, but the painters we used in Southern California (Hoppe Brothers) were the best I've ever witnessed. Man they could lay the paint down with a brush and it almost looked like it was sprayed it was so smooth. I'm just passing on information that I've heard them talk about and what I've watched them do !!

Good Luck and stay patient !


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