# Pre-primed Exterior "Fiberboard" Trim



## slickshift (Apr 8, 2007)

I'm not sure what it's called, but it looks like MDF (sawdust and glue) only rougher
Let's call it Wal*Mart furniture looking quality, exterior grade...but w/o the paper picture of wood "laminate" over top
Or maybe "MDF Ruff"

It was a sub job, so no skin off my azz...
But still...I wonder if it's going to become common and I'll need to deal with it under my own name

True, the Moorglo went on like buttah...production rate was great!
But (and it's a big butt)...IMHO each nail fill looked like one of those freeze thingies plantar wart removal situations
And every "iffy" end to end...caulk city - you can not sand anything smooth!

Now add the fact that I live 40 miles out into the North Atlantic
I haven't had below 80% humidity _inside_ my house since _I turned the heat off_
_And I haven't even opened any windows yet!_

I keep thinking of the time I saw some MDF used on an exterior repair, it didn't last a week before it puffed up like a puffer fish answering the doorbell and finding a Great White on the stoop

Frankly, my impression is that I'm appalled the H/O would spring for such a nice addition, and cheese out on the trim
But perhaps I'm being a little hasty (or "stuck-up" or "prejudice" or something)

Has anyone here dealt with this stuff before?
How's it hold up?
Any tips/tricks if I find myself facing it under my own company banner?
...or should I just run like Forrest Gump...

Thanks in advance,
---Slick


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## vermontpainter (Dec 24, 2007)

Its called MDO. Same stuff they make traffic signs out of. Oil primer and moorglo.


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## slickshift (Apr 8, 2007)

Hmmm...interesting


vermontpainter said:


> ...Oil primer and moorglo.


That was my first thought...oil prime on all 6 sides and it'll be fine

But truly, this company usually is very much a "quality over production" company, and I immensely enjoy working for them because of that, so I found it hard to believe this was just a "fill w/lightweight latex spackle and two coat Moorglo" deal
Nearly every nail indent, atop from being visible (a little mound around it) and non-sandable (grrrr), had "wood" (sawdust stuff) showing

Should I swing by in a few weeks (or a few hours as the weather's been lately) and look for some puffer fish?
Really, there were many cuts (especially miters) that were never primed
Frankly, it kinda scared the poop out of me while I was doing it
Fortunately, it wasn't my gig ya know...that was the only thing that got me through it "as spec'd"


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## DeanV (Apr 18, 2007)

A lot of my builders use that stuff. They all get one coat prefinished over however it comes from the factory (that light grey color) and we caulk and apply one coat in the field. Nail holes can stink and need glazing to keep water out. Carpenters need to prime all edges before they nail it, or it will swell up from the but ends.

For me, it seems pretty good so far. I am not convinced yet, but it is used on high end homes here.

Here is the instructions for Miratec:

PAINT APPLICATION :
1. Prime all exposed field-cut edges of MiraTEC trim and also topcoat those edges which will be exposed to the weather. Use a high quality
exterior primer formulated for use on composite wood. All cut or raw edges should be primed within 30 days of installation.
2. Coat all exposed surfaces including the bottom edge.
3. Finish MiraTEC trim with two coats of paint within 90 days of installation. If, due to unforeseen circumstances, the material is not painted
within 90 days, reprime the MiraTEC trim using an exterior primer that is specifically recommended for use on composite wood products
and is compatible with the topcoat to be used. Use the same primer for repair of any damage to the original factory-applied primer.
4. A total field-applied dry film paint thickness of a minimum of 2½ mils is required on MiraTEC trim. This requires the application of two or
more unthinned coats of paint at the spread rate recommended by the paint manufacturer. Note: The paint manufacturer may
require a primer and topcoat combination. Follow all paint manufacturers’ recommendations.


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## vermontpainter (Dec 24, 2007)

The nail holes do mushroom due to the density of the board, similar to mdf on interior. It does hold up well. We see it quite a bit, and it has a cousin which is the same only has one side with a osb type veneer for plywood applications without concern for delam.


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## slickshift (Apr 8, 2007)

Thanks guys!


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## nEighter (Nov 14, 2008)

if it is Miratec which is what you kinda discribed.. all you need is an acrylic primer. No oil is needed. I have been rebuilding houses with that stuff for 6yrs and no problems what so ever. You technically don't even need to prime. I have done it both ways, and have not seen a lick of a problem with not priming it.


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## nEighter (Nov 14, 2008)

DeanV said:


> A lot of my builders use that stuff. They all get one coat prefinished over however it comes from the factory (that light grey color) and we caulk and apply one coat in the field. Nail holes can stink and need glazing to keep water out. * Carpenters need to prime all edges before they nail it, or it will swell up from the but ends.*


That is near impossible to prime all edges while building. If it is caulked and the exposed surfaces (like on the 1"X2" pieces) are primed afterward there is no problem with this stuff.

honestly I can go out in my wood pile and pick some pieces out of it that are well over 2 yrs old, through rain snow and all the elements and there is no swelling and other than being dirty and a "little" weathered that Miratec still looks and FEELS great.. feels as in solid and sturdy, not mushy and worn. Seriously if you have a question about this stuff, buiding or painting wise let me know.


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## DeanV (Apr 18, 2007)

The carpenters I work behind always prime the cut ends before nailing it up. I have seen the butt ends swell up when they are not primed (especially the ends that are close to the ground where snow can sit or moisture can get at the bottom edge where trim runs down and the butt end is above a patio, deck, etc).


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## nEighter (Nov 14, 2008)

Sure. I am just saying this stuff is tough. I am uploading pics right now. Stuff that is actually greater than 2 yrs old.. could be over three it is just a small piece of scrap and has black on it from sitting shutters on it so I could spray them.. so that could be a house I did 3 yrs ago.. anyway pics in a second..


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## nEighter (Nov 14, 2008)

Sorry the quality kinda sucks. This is 2-3yr old Miratec laying in a woodpile unprotected from the elements. I live in Kansas and we see our fare share of nasty elements and high humidity. Piece below is NOT end primed.




























Same size no swelling. top board was from a repair job about 3 weeks ago.


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## DeanV (Apr 18, 2007)

Interesting. The carpenters I work with had put a piece of miratec in a puddle during one project, and said it had swelled up (I did was not on that project). Your piece looks fine though. I do think it is a good product, just want to see it in 10-20 years, since it is not a product you could really sand or scrape if needed.


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## JAYJAY (Sep 13, 2008)

Appiled that to corners in the victorian in my pics section. Stuff looks and feels like crap, but my brother in law that frames and then sides 10 million dollar houses and he claims they use it all the time (and knock on Mirtech) no problems yet. Stuff seems like sponge......


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## nEighter (Nov 14, 2008)

DeanV said:


> Interesting. The carpenters I work with had put a piece of miratec in a puddle during one project, and said it had swelled up (I did was not on that project). Your piece looks fine though. I do think it is a good product, just want to see it in 10-20 years, since it is not a product you could really sand or scrape if needed.


yeah will be interesting to see it in years to come  But what I have used of it it is pretty damn solid :thumbsup:



JAYJAY said:


> Appiled that to corners in the victorian in my pics section. Stuff looks and feels like crap, but my brother in law that frames and then sides 10 million dollar houses and he claims they use it all the time (and knock on Mirtech) no problems yet. Stuff seems like sponge......


well the alternatives are:

Hardi.. which comes in only certain sizes, and you need special (not wood) blades to cut it.. and it cracks VERY easily

Miratec

Azek or NOROT vinyl.. expensive.. 

smart.. 

or wood.

Pick your poison:jester:


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## DamonBoost (Jun 21, 2009)

nEighter said:


> That is near impossible to prime all edges while building. If it is caulked and the exposed surfaces (like on the 1"X2" pieces) are primed afterward there is no problem with this stuff.
> 
> honestly I can go out in my wood pile and pick some pieces out of it that are well over 2 yrs old, through rain snow and all the elements and there is no swelling and other than being dirty and a "little" weathered that Miratec still looks and FEELS great.. feels as in solid and sturdy, not mushy and worn. Seriously if you have a question about this stuff, buiding or painting wise let me know.


What are you using to fill the nail holes in Miratec?


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## Kelly Painting (Apr 17, 2007)

Seen it around here a bit, but don't know how I like it with water and expansion and contraction. Azak got big around here last year and we use it alot. Some houses we even replaced all the trim with azak. It's kinda pricy, but worth it. We all have to realize that bulding products will change and eventually there will be no more wood on the exterior of a house, we will have to learn new meathods and new products.


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## LOSTinDETAILS (Jun 17, 2009)

Hardboard is what I think it is and I not a big fan of it. It is cheap in price compared to some other choices. It reminds me of masonite. I have LP hardboard siding on my house and it does exactly like the guys mentioned about the nail heads mushrooming. Granted it is face nailed and coated but water will and has found its way past.


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## nEighter (Nov 14, 2008)

I have thought about Miratec, if it is submerged it does swell but it must sit for a long time. Over the winter I had one piece that was submerged in water for months and it did swell. but you saw the pieces that were just out in the open and not submerged in water. I like the stuff. any cut or exposed end should be primed.


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## vermontpainter (Dec 24, 2007)

I have a chipmunk that got itself submerged in a 5 gal pail behind my shop. Its the size of a football. I would post a picture but someone would surely alert PETA.


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## Bender (Aug 10, 2008)

And OSHA


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## nEighter (Nov 14, 2008)

I met with the area's Miratec rep today, got a lot of literature. BTW he reinforced that there is no need to prime this stuff prior to painting. 100% acrylic and you are good to go! But if you want to prime the cut edges, acrylic latex primer is all that is needed.


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