# Mdf Pre-primed Hollowcore Doors



## blueracer70 (Sep 9, 2010)

Hi hope to get some sound advice, we have imported some doors from China and they have been pre-primed. Our painters have applied a coat having initally sanded down and there are tramlines down the edges of the doors. The painter is telling me it is due to the process the door went through when being pre-primed (through rollers) that have left marks. He is not offering any advice in rectifying this. Is this a common problem? could the lines be down to the type of paint he has used. We want to end up with a smooth gloss finish but with this line issue evident he tells me the top coat will make it even more noticable. Any advice would be grateful.


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## Retired (Jul 27, 2010)

blueracer70 said:


> Hi hope to get some sound advice, we have imported some doors from China and they have been pre-primed. Our painters have applied a coat having initally sanded down and there are tramlines down the edges of the doors. The painter is telling me it is due to the process the door went through when being pre-primed (through rollers) that have left marks. He is not offering any advice in rectifying this. Is this a common problem? could the lines be down to the type of paint he has used. We want to end up with a smooth gloss finish but with this line issue evident he tells me the top coat will make it even more noticable. Any advice would be grateful.


Change painters.


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## ReNt A PaInTeR (Dec 28, 2008)

*BUY AMERICAN :thumbup:*


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## DeanV (Apr 18, 2007)

I see that a lot on mdf door trim. It needs to be filled and sanded smooth. If there is a lot of it, it may cost extra to fix if he is on budget pricing for your job or there is a ton of filling to do.

It does not come from his spraying.

Also, the clay coat on mdf is too voc high to be applied in USA. S. American is where most of it is from around here. I am sure China does there part as well.


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## Wolfgang (Nov 16, 2008)

These are tough situations. What I did was after prepping the doors I would apply a wet coat of primer so I could actually see if the mfg roller marks would still be visible. It was always alot of fun finding those on stained doors also, because many times they wouldn't show up until the first coat of finish was put on.


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## TJ Paint (Jun 18, 2009)

did you go with the cheapest bid? if you did, he probably doesn't want to spend anymore time on it. He probably realizes hes not going to make any money on your project trying to fix all the quirks in the Chinese doors you bought on the cheap,


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## Rcon (Nov 19, 2009)

If it's a result of the door manufacturing process then your painter isn't at fault. If you want the lines fixed, it should just be a matter of extra filling and sanding. Expect an up-charge for the extra work though.



> did you go with the cheapest bid?


That would be my guess if he isn't 'offering' solutions.


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## jack pauhl (Nov 10, 2008)

its likely to be one of 2 things. 

1) the doors had these lines from the factory but I have never seen "lines" from the factory primer. I have however seen pre-primed doors with a "orange peel-like" texture on smooth MDF that covers the entire smooth surface door.

2) your painter rolled these doors and left them to dry and sounds like may have left roller marks in the finish. If your painter didnt spray them, he likely rolled them.


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## Retired (Jul 27, 2010)

ReNt A PaInTeR said:


> *BUY AMERICAN :thumbup:*


Those closet doors are a bitch!


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## Ranger72 (Jul 3, 2010)

jack pauhl said:


> its likely to be one of 2 things.
> 
> 1) the doors had these lines from the factory but I have never seen "lines" from the factory primer. I have however seen pre-primed doors with a "orange peel-like" texture on smooth MDF that covers the entire smooth surface door.
> 
> 2) your painter rolled these doors and left them to dry and sounds like may have left roller marks in the finish. If your painter didnt spray them, he likely rolled them.


I have seen some of these mdf primed doors have that stippled primer from the factory were it was heavier in one spot down the door. (A line). A little sanding and filling takes care of it pretty easily. The primer they use seems to sand fairly easily, almost chalk like.


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## jack pauhl (Nov 10, 2008)

Ranger72 said:


> I have seen some of these mdf primed doors have that stippled primer from the factory were it was heavier in one spot down the door. (A line). A little sanding and filling takes care of it pretty easily. The primer they use seems to sand fairly easily, almost chalk like.


Yep thats the nice thing, they do sand out easy if you can spot them. The most recent smooth MDF panel doors I've seen were a huge improvement from years past. The recent ones have a nice smooth primer finish but that varies from each manufacturer. 

I guess this might be a stretch but I suppose these MDF doors could have marks left behind from possibly racking them. This is where those pics come in handy.


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## DeanV (Apr 18, 2007)

While I have not seen it on doors, I see it often on trim. It is a very thin, straight line depression in the MDF. It is hard to see until the trim paint hits it. If you look for it you can usually spot it earlier unless it is a very shallow one.


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## aaron61 (Apr 29, 2007)

These are cam roller marks.This would be a bad (cheap) batch of doors that they probably had a hard time unloading on someone. 

Things got out of alinement in the factory and a bunch of doors got f'ed up.
Like Dean said,I see it on crown molding quite a bit.


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## NCPaint1 (Aug 6, 2009)

aaron61 said:


> These are cam roller marks.This would be a bad (cheap) batch of doors that they probably had a hard time unloading on someone.
> 
> Things got out of alinement in the factory and a bunch of doors got f'ed up.
> Like Dean said,I see it on crown molding quite a bit.


Thnk you China!! So what's cheaper. Getting cheap jacked up doors and paying someone to make them look good, or buying good doors and paying less in labor?


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## Wolfgang (Nov 16, 2008)

The tough ones are the doors that are six-panel with the primed woodgrain look.


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## Ranger72 (Jul 3, 2010)

Wolfgang said:


> The tough ones are the doors that are six-panel with the primed woodgrain look.


I find those the easiest to paint personally.


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## Wolfgang (Nov 16, 2008)

I was referring to the roller cam marks on them.


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## Workaholic (Apr 17, 2007)

I agree with the group, it is fixable with a small amount of prep and primer. Try and communicate with your painter about what your expectations are. It is not his fault that you bought cheap damaged doors so it should be an add on for your part or a little PR on his depending on how many doors we are talking about. 

Blue, I just noticed you were not quite a DIY but a builder you might want to try www.contractortalk.com as it has a mix of all the trades and not just a group of painters as this site is a dedicated professional painting site.


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## Ranger72 (Jul 3, 2010)

Wolfgang said:


> I was referring to the roller cam marks on them.


Yeah, I realized that is probably where you were going with that after I replied.


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## MNpainter (Jul 17, 2008)

Ranger72 said:


> I find those the easiest to paint personally.


:yes::yes: steve
However ,I always have to prime and sand the edges


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## TDTD (Jun 10, 2010)

Pre-primed does not mean "ready to slap paint on".

My instinct is to suspect that the painter didn't have a good look at the doors before painting them. However, agree with JP that pics would be very helpful.

Anything I've ever painted that was pre-primed that I wanted to look any good always needed a little once over with a little fill, some 150 and spot prime here and there.:thumbsup:


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## VanDamme (Feb 13, 2010)

TDTD said:


> Pre-primed does not mean "ready to slap paint on".
> 
> My instinct is to suspect that the painter didn't have a good look at the doors before painting them. However, agree with JP that pics would be very helpful.
> 
> Anything I've ever painted that was pre-primed that I wanted to look any good always needed a little once over with a little fill, some 150 and spot prime here and there.:thumbsup:


I always prime pre-primed woodwork and doors. The primer they used sucks IMO


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## Andyman (Feb 21, 2009)

Cheap door + Cheap paint contract = Cheap results 

Not saying the cheap painter didn't jack them up but maybe you can call China and ask them about their quality control.


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## NCPaint1 (Aug 6, 2009)

Better get your RRP approved lead test kits out for the Chinese doors.


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## TJ Paint (Jun 18, 2009)

NCPaint1 said:


> Better get your RRP approved lead test kits out for the Chinese doors.


yeah no doubt, that's something that came to mind when I initially read the op.


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## Retired (Jul 27, 2010)

NCPaint1 said:


> Better get your RRP approved lead test kits out for the Chinese doors.


I agree. Those Chinese hollow core lead doors melt at 327 deg C and change. I can remember when they were still made from old beer cans back in the day when high quality meant something and men were men and women were women and other things too.


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## TJ Paint (Jun 18, 2009)

you people notice the op hasn't come back for more conversation? Seems like this happens 89% of the time.




Retired said:


> I agree. Those Chinese hollow core lead doors melt at 327 deg C and change. I can remember when they were still made from old beer cans back in the day when high quality meant something and men were men and women were women and other things too.


you're kinda silly sometimes, but I wouldn't want to change ya.:thumbsup:


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## NCPaint1 (Aug 6, 2009)

Hell, buy a few Matchbox cars from China and test those for lead too while you're at it.


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## jack pauhl (Nov 10, 2008)

VanDamme said:


> I always prime pre-primed woodwork and doors. The primer they used sucks IMO


I've been seeing some nicer (primer) used on some of the doors recently. Primer that feels harder and almost has a sheen to it for better gloss retention. But like any other product, there are so many different brands using different product. Im sure you've seen preprimed door jambs with one primer and the casing with another and the baseboard with something different. And the painter is suppose to make it all look the same. I work primarily in new construction, I'm guessing I've painted over 30,000 of these doors by now.


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## TJ Paint (Jun 18, 2009)

jack pauhl said:


> I work primarily in new construction, I'm guessing I've painted over 30,000 of these doors by now.


and you're not retired yet? :jester:


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## Retired (Jul 27, 2010)

Just in case no one has done this, 30,000 Chinese doors equals give or take a billion square feet this figure is also the approximate number of Chinese living in China.

I wonder if they make lead testing kits too?


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## MNpainter (Jul 17, 2008)

jack pauhl said:


> I've been seeing some nicer (primer) used on some of the doors recently. Primer that feels harder and almost has a sheen to it for better gloss retention. But like any other product, there are so many different brands using different product. Im sure you've seen preprimed door jambs with one primer and the casing with another and the baseboard with something different. And the painter is suppose to make it all look the same. I work primarily in new construction, I'm guessing I've painted over 30,000 of these doors by now.


IMHO if the primer affects your final work you are not using quality paint. I have never had an issue such as you describe. YMMV. steve


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## jack pauhl (Nov 10, 2008)

MNpainter said:


> IMHO if the primer affects your final work you are not using quality paint. I have never had an issue such as you describe. YMMV. steve


That primer coat has everything to do with the finish. Quality paint has nothing to do with it. Nothing at all to do with it. I cant believe you posted that. Seriously. Which wonder product are you using that is unaffected by the factory MDF primer? You just debunked the whole purpose of primer for producing quality finishes with your comment. This might not be an issue for the houses you work on in your area but the primer coat on MDF is a huge issue elsewhere. This is why some guys (self included) re-prime all of that MDF so that quality paint actually produces the finish it was intended to not just one that "looks good".


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## DeanV (Apr 18, 2007)

This reminds me of one time when our blue tape pulled the paint off all the door trim edges but not the baseboards. The rep for the trim said it was because we primed the pre-primed MDF. I called BS on that one.


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## VanDamme (Feb 13, 2010)

> I'm guessing I've painted over 30,000 of these doors by now.


I painted 2,000 doors for one job. Doors getting shipped to Japan, and I'm sure I'm no where near 30,000 doors painted. Probably closer to 5,000, but I don't keep track.


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## VanDamme (Feb 13, 2010)

MNpainter said:


> IMHO if the primer affects your final work you are not using quality paint. I have never had an issue such as you describe. YMMV. steve


I agree with JP on this one.


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## MNpainter (Jul 17, 2008)

jack pauhl said:


> That primer coat has everything to do with the finish. Quality paint has nothing to do with it. Nothing at all to do with it. I cant believe you posted that. Seriously. Which wonder product are you using that is unaffected by the factory MDF primer? You just debunked the whole purpose of primer for producing quality finishes with your comment. This might not be an issue for the houses you work on in your area but the primer coat on MDF is a huge issue elsewhere. This is why some guys (self included) re-prime all of that MDF so that quality paint actually produces the finish it was intended to not just one that "looks good".


As usual JP you make broad sweeping staements. Your comment was about differnt sheen levels of primer making it difficult to make all pieces look the same.I HAVE NOT had this problem , Period. Do not put words in my mouth. Primer is of course needed. But, Quality paint will for sure make up for the variations in the primer that you refered to.
steve. PS not at 30000 doors only a few hundred.So....


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## blueracer70 (Sep 9, 2010)

Thanks to all the helpful comments, apologies for delayed reply too, diff time zones and rarely get a chance to log back on to pc during week. The quality of doors are actually A1 the primer has just run on the edges, I asked the factory on their processing with primer and it was sprayed on so not sure about this cam rolling problem.I will take some photos and post on. I have suggested to the painter to give it a filler application and then sand down but as you know it is all cost realted. As you rightly point out I am a builder and for several years the painters have been aware that they get paid to paint the doors in accordance with the codes. I.e. 3 coats undercoat,prime,gloss but the reality is they spray the doors with a one coat application. Of course they still get the rate for the door. But.....now there is a situation where these doors need a bit of prep work the cap is out for more on the rate.! my dissapointment is that this two way street is now a one way! thanks again guys


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## Retired (Jul 27, 2010)

VanDamme said:


> I painted 2,000 doors for one job. Doors getting shipped to Japan, and I'm sure I'm no where near 30,000 doors painted. Probably closer to 5,000, but I don't keep track.


Keeping track of 2,000 doors is a good start. Not keeping track of the rest isn't. Did they get put on a boat and it sank? I'll bet the Japanese soybean counters were on top of that deal.


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## Retired (Jul 27, 2010)

blueracer70 said:


> Thanks to all the helpful comments, apologies for delayed reply too, diff time zones and rarely get a chance to log back on to pc during week. The quality of doors are actually A1 the primer has just run on the edges, I asked the factory on their processing with primer and it was sprayed on so not sure about this cam rolling problem.I will take some photos and post on. I have suggested to the painter to give it a filler application and then sand down but as you know it is all cost realted. As you rightly point out I am a builder and for several years the painters have been aware that they get paid to paint the doors in accordance with the codes. I.e. 3 coats undercoat,prime,gloss but the reality is they spray the doors with a one coat application. Of course they still get the rate for the door. But.....now there is a situation where these doors need a bit of prep work the cap is out for more on the rate.! my dissapointment is that this two way street is now a one way! thanks again guys


Once again going by your original question and the information both on the line and between the lines, IMO, changing painters would solve most of your problem. I think what you are dealing with is somebody who applies some paint and not a skilled professional. Inspection and repair of any trim packages including doors is SOP for a pro or at least most who call themselves pros.

From your latest post, this rings true. Who ever these cats are,

what they want to do, is blow and go. 

One coat? Can be done. 20 mils of elastomeric should do the trick. The R value of the seal should improve greatly. 

Any manufacturing facility that can fabricate doors ain't IMO gonna roll on the primer, even in Pittburgh.


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## Workaholic (Apr 17, 2007)

blueracer70 said:


> but the reality is they spray the doors with a one coat application. Of course they still get the rate for the door. But.....now there is a situation where these doors need a bit of prep work the cap is out for more on the rate.! my dissapointment is that this two way street is now a one way! thanks again guys


I agree with Retired if your painters are giving a one coat application on these preprimed doors then they are not handling it right.


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## Retired (Jul 27, 2010)

Workaholic said:


> I agree with Retired if your painters are giving a one coat application on these preprimed doors then they are not handling it right.


You better agree or else I will send you bitchy whiny PMs or lay down on the floor, kick my feet and hold my breath.


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## Workaholic (Apr 17, 2007)

Retired said:


> You better agree or else I will send you bitchy whiny PMs or lay down on the floor, kick my feet and hold my breath.


My own kids can't even get away with using those tricks anymore. :laughing:


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## Retired (Jul 27, 2010)

Workaholic said:


> My own kids can't even get away with using those tricks anymore. :laughing:


That's probably because your kids aren't painters..


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## blueracer70 (Sep 9, 2010)

*Update*

Now I am being told that the MDF board should only be primed with an oil based sealer because waterbased will swell the door and cause issues? where we are they typically have a masonite skin on the mdf, whereas I dont believe these doors have this, could this be the problem that the painter has primed with a waterbased?


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## Retired (Jul 27, 2010)

blueracer70 said:


> Now I am being told that the MDF board should only be primed with an oil based sealer because waterbased will swell the door and cause issues? where we are they typically have a masonite skin on the mdf, whereas I dont believe these doors have this, could this be the problem that the painter has primed with a waterbased?


Hollowcore doors generally are for interior usage. They have six sides. One of the great points of contention with professional painter is, does one prime or seal all six sides. Hollowcore doors IMO,yes. If by chance they are to used with one face exposed to the weather then again IMO prime or seal all six sides. 

Some door skins are Masonite or a Masonite clone. Some doors are MDF or and MDF clone. The Chinese doors you are using since there is no data supplied could be made of rice husks.

Your line of questioning is becoming confusing or you are getting BSed by your current painter. I understood the original problem to be with the prime coat as supplied by the Chinese manufacturer. 

Best bet IMO, haul yourself to a real paint store, have the manager recommend a skilled contractor not some dude that looks like he spent the night in a drum of paint and needs a shower, pay the guy for an hour or two of his time and solve your problem. Me? I'd ****can the "painter" you have now.


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## blueracer70 (Sep 9, 2010)

"Your line of questioning is becoming confusing or you are getting BSed by your current painter. I understood the original problem to be with the prime coat as supplied by the Chinese manufacturer.

Hi Retired thanks again for your valued opinion, sorry to divert but the painter initally suggested the primecoat caused the issue, now he suggests it is actually the surface of the MDF board itself. "

The supplier has confirmed he used standard Medium Density Fibreboard pre-primed with a water based sealer. Comments i am getting this end are because it does not have a masonite skin there could be problems caused by swelling. Also concerns are how to prevent moisture getting into the doors causing swelling.

I have suggested applying filler where required and insisting on a full seal to all six sides, but my confusion is in mixed comments now on water based or oil based and if either one of these causes problems with MDF surface


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## Retired (Jul 27, 2010)

I'm sticking to my story on this one. Your painter is BSing you. I assume you are the guy writing the checks and he is an employee or sub. This is rookie stuff he is talking. 

What is it you are "filling"? MDF is babybutt smooth and seals well using an alkyd primer/undercoater, if the skins are really MDF and not some knock off. Also to be "sealed" you are dealing with more than the skins. Top, bottoms and edgers come into play. These being areas of potential moisture ingress swelling and other rather nasty problems down the line. 



Masonite unless liscensed to a Chinese manufacturer is a patented and trademarked material and since inception has grown to a substantial line of products bearing the label.


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## bay area contractor (Sep 19, 2009)

Wouldn't be easy to just paint over factory primed doors etc. Number one, the primer is only intended as a temporary to prevent excessive moisture intrusion. Most come on a boat from China. You have no idea what primer they used. Sand all surfaces and re-prime and and sand again for best results.


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