# Interior MDF doors



## Aiko1665 (Jul 5, 2020)

Looking for some assistance in how to properly prep MDF interior doors, still can't get a smooth finish after priming, sanding and painting...


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## SS_painting (Jan 11, 2020)

Aiko1665 said:


> Looking for some assistance in how to properly prep MDF interior doors, still can't get a smooth finish after priming, sanding and painting...


Try priming with BIN. It won't raise the grain much of at all. 

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## Aiko1665 (Jul 5, 2020)

Thanks and should I invest in a good sprayer for finish coat, and if so do you have a recommendation, thanks.


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## SS_painting (Jan 11, 2020)

Aiko1665 said:


> Thanks and should I invest in a good sprayer for finish coat, and if so do you have a recommendation, thanks.


I use a Graco 490 for pretty much everything

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## CApainter (Jun 29, 2007)

Are these pre primed MDF doors with stamped wood grain?


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## Aiko1665 (Jul 5, 2020)

They are pre-primed but I tried just painting over the factory primer with a smooth roller and didn't get a smooth finish.....


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## Aiko1665 (Jul 5, 2020)

Sorry didn't answer the rest of your question, no they are not stamped. Smooth finish...


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## Joe67 (Aug 12, 2016)

When you say you didn't get a "smooth finish" are you talking about roller stipple? MDF surfaces are pretty smooth and you shouldn't get any roughness out of them. Anything that was ripped, though will be fuzzy and sand out ok after priming. But the door faces shouldn't be rough at all.


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## Woodco (Nov 19, 2016)

Sometimes, if you dont use a solvent based primer, water will swell the fibers of the MDF. I had bad experience with a house full of doors....


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## canopainting (Feb 12, 2013)

Aiko1665 said:


> Thanks and should I invest in a good sprayer for finish coat, and if so do you have a recommendation, thanks.


Titan ED 655, they are awesome I have 4 of em.


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## finishesbykevyn (Apr 14, 2010)

Or maybe just try straining your paint and using a lint free roller sleeve.
Are you a painting contractor?


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## MattWll (Jul 7, 2020)

Titan ED 655 +1


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## futtyos (Aug 11, 2013)

*Gardz maybe*



Aiko1665 said:


> They are pre-primed but I tried just painting over the factory primer with a smooth roller and didn't get a smooth finish.....


I had several doors to paint in a condo remodel job that were flat, but with one inset panel. They were MDF and factory primed. You will probably read here a bunch of times where re-priming factory primed doors is recommended as factory primers are really cheap and a primer is chemically only good to paint over for a period of time, after which it loses its' chemical bonding properties.

I decided to take a chance and roll a coat of Gardz over these doors. The Gardz went onto the doors visually like water would go onto new dry white t-shirts, the wet area appearing darker than the dry. That is exactly what happened, which told me that the Gardz soaked through the factory primer and sealed the doors very well. Painting them was a breeze! 

I have also used Gardz over factory primed MDF trim to good effect.

futtyos


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## RH (Sep 7, 2010)

futtyos said:


> I had several doors to paint in a condo remodel job that were flat, but with one inset panel. They were MDF and factory primed. You will probably read here a bunch of times where re-priming factory primed doors is recommended as factory primers are really cheap and a primer is chemically only good to paint over for a period of time, after which it loses its' chemical bonding properties.
> 
> I decided to take a chance and roll a coat of Gardz over these doors. The Gardz went onto the doors visually like water would go onto new dry white t-shirts, the wet area appearing darker than the dry. That is exactly what happened, which told me that the Gardz soaked through the factory primer and sealed the doors very well. Painting them was a breeze!
> 
> ...


So you like Gardz eh? Who knew?


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## juanvaldez (Sep 7, 2019)

finishesbykevyn said:


> Or maybe just try straining your paint and using a lint free roller sleeve.
> Are you a painting contractor?



Doesn’t sound like one.....


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## juanvaldez (Sep 7, 2019)

But I’ll give it a reply:
Sometimes this has happened with us if we are working too fast and the primer hasn’t dried overnight, or is too thin a coat, especially a water based primer. 

We try to use BIN when possible as usually we are doing case base and other trim at the same time, so that usually helps. 


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## Lakesidex (Oct 9, 2011)

Try the Advance primer for pre-primed MDF.

Sands like a champ.


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## jennifertemple (Oct 30, 2011)

welcome to Paint talk, a forum for professional painters. What is your paint related field or trade or are you a home owner doing work for yourself?
@*futtyos* did you drop the ball on this one? :vs_smirk:
( you are the one that commonly says IBTMTTO)


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## SS_painting (Jan 11, 2020)

jennifertemple said:


> welcome to Paint talk, a forum for professional painters. What is your paint related field or trade or are you a home owner doing work for yourself?
> @*futtyos* did you drop the ball on this one? :vs_smirk:
> ( you are the one that commonly says IBTMTTO)


I dunno, I quite like the discussion here.
There is the odd homeowner asked question that I wish wasn't closed just because of the topic. 

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## Vylum (May 12, 2016)

sounds like a technique or equipment issue


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## jennifertemple (Oct 30, 2011)

SS_painting said:


> I dunno, I quite like the discussion here.
> There is the odd homeowner asked question that I wish wasn't closed just because of the topic.
> 
> Sent from my SM-G950W using Tapatalk


If we allow any DIYers than it would not be fair to ban those whose discussion we happen to dislike or find uninteresting. If you want to continue discussions with DIYers, there is a sister site devoted to them. Such discussions would be properly continued on the sister DIY site. So I repeat the question to @Aiko1665, are you a pro and what area of the paint professions are you in?


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## cocomonkeynuts (Apr 14, 2017)

MDF -> FFLP312 -> 1WB.200 undercoater -> Cabinetcoat.


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## futtyos (Aug 11, 2013)

*My bad*



jennifertemple said:


> welcome to Paint talk, a forum for professional painters. What is your paint related field or trade or are you a home owner doing work for yourself?
> @*futtyos* did you drop the ball on this one? :vs_smirk:
> ( you are the one that commonly says IBTMTTO)


Yes, Jennifer, it does appear that YBTMTTO and not me. I did like the question, though, and thought I might chime in with something of interest. I guess my love of Gardz clouded my good judgement! 

futtyos


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## jennifertemple (Oct 30, 2011)

futtyos said:


> Yes, Jennifer, it does appear that YBTMTTO and not me. I did like the question, though, and thought I might chime in with something of interest. I guess my love of Gardz clouded my good judgement! futtyos


 Well, Mod RH was here and he, apparently, liked the question too! We do seem to be getting a little sloppy allowing carpenters and DIYers we like to have their membership and posts remain. It does seem unfair to those that get the boot. As for other trades, there is another sister site "Contractor Talk" On that site any contractor can join and visit other trades and comment as and when appropriate. Even there it is PROS ONLY.

Also Cricket says: "PaintTalk.com is designed to be a pros only community serving professional painters, apprentices, and related professional paint fields. Anyone who works as a professional painter, apprentice, or in a related professional paint field is welcome to join the site and participate in our forums." "If you have not already done so, please take a moment to fill out our required user *profile field*, your paint related field/trade and general location." Most are tardy at best and the DIYer never!


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## Wildbill7145 (Apr 30, 2014)

The MOD squad makes judgement calls. There's no "getting sloppy" whatsoever. If you don't like the calls getting made, take it up with the admins of the site rather than complaining about it on the forum.


The OP of this thread hasn't even logged back on since the day they posted this question, so we may just never know whether they're a pro painter or not. So, how would we determine whether or not their post/thread should remain. It's a judgement call.


This is also part of the forum rules:
"*2a*. Users shall not question or debate a moderator decision publicly on the message board. In the event of a disagreement or questioning of a moderator's decision or action users should contact the moderator(s) or admin(s) via PM."


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## slinger58 (Feb 11, 2013)

I had rule 2a explained to me in detail some time ago. I may forget some other forum rules, but 2a is with me forever. 


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## Joe67 (Aug 12, 2016)

I think the mods are great.

But I'm mostly saying that so that the next time I cross a line I get mercy!

But seriously, it's a well run site, and interesting Qs or not it's all or nothing. You either have a site for profs ... or you don't. Handy that there's a DIY sister site. 

The only thing that drives me nuts is how the ads work. I know they're part of the juice that keeps things alive. But do they really have to unpredictably bounce everything up and down as they appear and change in variable sizes?

How the ads work, of course, has nothing to do with the mods.


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## RH (Sep 7, 2010)

Wildbill7145 said:


> The MOD squad makes judgement calls. There's no "getting sloppy" whatsoever. If you don't like the calls getting made, take it up with the admins of the site rather than complaining about it on the forum.
> 
> 
> The OP of this thread hasn't even logged back on since the day they posted this question, so we may just never know whether they're a pro painter or not. So, how would we determine whether or not their post/thread should remain. It's a judgement call.
> ...


Along those same lines, if we as moderators have let anything slip it's been in calling out members' who are in violation of rule _*2b. Users shall not question or debate another member's qualifications publicly on the message board. Instead, any questionable posts should be reported using the "Report Post" button. *_

As a regular member, feel free to welcome newbies. Heck, even feel free to answer some basic questions about site navigation, but pretty much anything beyond that is exceeding your mandate - especially since you don't have any mandate. *From this point on, members who publicly question or challenge another member's status can expect to be given a vacation from the site.*

Want to help? REPORT THE POST if you have concerns about it. Do not take it upon yourself to question if a member is an actual professional painter or not. In other words; stay in your lane! 

If you do report a post and no action is forthcoming after an hour or so, you can likely figure that the mods determined no action was required. And although that may not be what you wanted, just accept it and move on.

And finally, if you do have a question about navigating the site and the forum rules, go to the "Quick Links" section (on the blue bar just below the first page heading). After that, posting your question to the group will usually get a response from a member (usually correct), or, after twenty posts, you can private message (PM) a moderator. Contacting admin should only be done after all those avenues have been exhausted or if you are having issues with a specific moderator.


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## CApainter (Jun 29, 2007)

You think PT DIY'ers are treated poorly, try the HVAC Talk. Those folks don't play around.


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## Wildbill7145 (Apr 30, 2014)

CApainter said:


> You think PT DIY'ers are treated poorly, try the HVAC Talk. Those folks don't play around.



I can only speak to PT which I'm a member of. CT, which I look at every now and again, not a member of and never will be, and I would never post on. DIY, which I would revoke my membership of if I could, but I can't. Glad I can figure out most crap around my house on my own.





We've got it pretty good here folks. IMO. As quiet as it may be at times, poke around. Sometimes the home front isn't so bad. Relatively speaking.


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## CApainter (Jun 29, 2007)

Wildbill7145 said:


> I can only speak to PT which I'm a member of. CT, which I look at every now and again, not a member of and never will be, and I would never post on. DIY, which I would revoke my membership of if I could, but I can't. Glad I can figure out most crap around my house on my own. We've got it pretty good here folks. IMO. As quiet as it may be at times, poke around. Sometimes the home front isn't so bad. Relatively speaking.


Quiet is good. Just like in real life. Some people thrive on the noise while others thrive on the silence. I subscribe to the latter. That's why PT is the only social site I visit. Sure, there's the occasional ruckus, but it's buffered by a culture of civility, humility, and reason. 

..and we owe it all to the mod's...*Bam! Making points!*


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## futtyos (Aug 11, 2013)

*My response to CAp*



CApainter said:


> Quiet is good. Just like in real life. Some people thrive on the noise while others thrive on the silence. I subscribe to the latter. That's why PT is the only social site I visit. Sure, there's the occasional ruckus, but it's buffered by a culture of civility, humility, and reason.
> 
> ..and we owe it all to the mod's...*Bam! Making points!*


IASHTYFTW!

futtyos


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## CApainter (Jun 29, 2007)

futtyos said:


> IASHTYFTW!
> 
> futtyos


I'm so happy that you're so happy!


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## hasnazameer (Jul 20, 2020)

use a good sprayer.


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## celicaxx (May 29, 2015)

I think Jack Paul wrote about this before, how he likes Gardz for MDF, as MDF even with a factory primer is a very porous surface. Gardz seals the surface so it's no longer very porous, thus paint flows out better and is more workable. So, when you have a porous surface, the more porous the surface, the faster paint will dry on you. Thus, you need a thinner paint that dries slower, ideally, or you need to change your technique to go faster while getting a nice, consistent, even coat of paint without runs/sags/etc. That's pretty much painting 101, surface porosity determines everything. You'll notice even painting over dead flat ceiling paint, you get more drag than painting over a satin or eggshell wall, it's because of the surface porosity. 










This is a door I did, with factory MDF primer, pretty much no prep beyond dusting it off, and with two coats of Muralo Ultra High Gloss applied with an Arroworthy 3/8" nap mini-roller. It looks very sprayed to me if I use this technique a paint like Muralo/Cali Ultra, or Benjamin Moore Advance. I think on this I spiked the Muralo with maybe 4oz or water for the gallon, but I'm not sure. I like the Arroworthy 3/8" nap mini-rollers for trim and doors in general, as if you have a good flowing paint, they tend to leave a nice sprayed looking finish, better in many cases than a foam roller or a Wooster Red Feather. 

I don't see a point in repriming factory MDF personally as even if the factory primer is pretty meh, you're still at the mercy of that primer for adhesion ultimately, and by putting primer on you're just adding more potential for orange peel, brush marks, etc, and another layer of paint to lose the "definition" of the fake wood grains in the MDF. Of course if it's somehow damaged and there's stains/etc, then those need to be dealt with spot primed maybe with BIN or Kilz in a rattlecan, but priming a whole MDF door seems sort of ridiculous to me, unless maybe you're Jack Pauhl and using Gardz which is apparently almost water thin and won't do much negative in all those other manners, but I've never used it myself so I can't give an opinion. 

If you have a faster drying paint like say, Aura, or something nasty awful and ropey to use like Coverstain (hope to never use that again now...) you're better using a roller like a foam roller or a Wooster Red Feather where the nap is very very short, as it will be thick and dry too fast to ever level out well, so you're better off just using a small/almost no nap roller like that in those cases.


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## futtyos (Aug 11, 2013)

*Gardz is great over MDF!*



celicaxx said:


> I think Jack Paul wrote about this before, how he likes Gardz for MDF, as MDF even with a factory primer is a very porous surface. Gardz seals the surface so it's no longer very porous, thus paint flows out better and is more workable. So, when you have a porous surface, the more porous the surface, the faster paint will dry on you. Thus, you need a thinner paint that dries slower, ideally, or you need to change your technique to go faster while getting a nice, consistent, even coat of paint without runs/sags/etc. That's pretty much painting 101, surface porosity determines everything. You'll notice even painting over dead flat ceiling paint, you get more drag than painting over a satin or eggshell wall, it's because of the surface porosity.
> 
> 
> 
> ...


I agree with Jack Pauhl (Brian Havana) about using Gardz over factory primed MDF. I had 3 doors to do that had 1 inset panel on each side. When I applied the Gardz, it soaked right through the cheap factory primer and probably helped it bond better to the MDF. When I applied the Gardz, the primer darkened as would a white t-shirt when water is splashed onto it. The darkness went away after the Gardz dried with virtually no roller stipple to speak of.

When painting the doors, if I recall correctly, I may have cut in the inset panel with an artist's brush to avoid brush marks, then rolled the flat areas with this mini roller in a 1/4" nap:

https://www.sherwin-williams.com/painting-contractors/products/contractor-series-woven-mini-rollers

The doors came out very nicely and the paint remained very workable without drying too fast.

On flat doors without panels I use the Wooster 5/16" Micro Plush 9" wide cover (the 5/16" Micro Plush is also available in a 4" mini roller size which I also use for rolling out paneled doors). I asked a clerk at my local Benjamin Moore dealer what the most popular roller cover was for painting flat doors and he said the 5/16" Micro Plush was.

I heartily recommend Gardz over factory primed MDF and encourage those here who haven't yet tried it to do so.

futtyos


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## Woodco (Nov 19, 2016)

BM has a product similar to Gardz buts designed to be sandable, interior/exterior, and can even be a finish itself. My store didnt have any luck ordering any though. I believe the product is Corotech, clear acrylic sealer. It seems like this would be better to use on MDF. Gardz is also REALLY nasty to spray. Personally, if I feel the need to reprime, Im gonna stick to quick dry oil. http://benjaminmoore.pl/en/our-prod...s/corotech-reg-clear-acrylic-sealer-v027.html


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