# Can you paint masonite siding??



## AtlanticWBConst. (May 12, 2006)

opee said:


> Some of our masonite siding is chipping off and we would like to paint it, but someone had told me you can't paint masonite siding. Is this true, and if it is not true, are there any special steps to painting it?
> 
> Thanks!


First off, you can paint masonite siding. The issues revolve around masonite siding that has been up for a while and has started 'chaulking'.

Here is a link with a description of steps to take. Go to the 3rd response down:

http://ths.gardenweb.com/forums/load/remodel/msg100310066922.html?7


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## joewho (Nov 1, 2006)

!!!!!!!YOU NEED TO KNOW THIS!!!!!!!!!!!

Where ever the surface paint is gone or repairs to be made, DO NOT USE WATER. Don't wash the house first. You need to use an oil or shellac based, quick dry coating before you do anything else.

This is where the lawsuits are coming from:
The subsurface acts like cardboard or bare drywall. You can't scrape it, sand it and certainly don't put water on it. It will absorb the water, swell and buckle. If you try to prime with water base, it will bubble, you'll try to repair the bubble and that, in turn, will cause more damage. All the bare spots need to be sealed up with shellac or zinsser shields. I would use shellac on an exterior. 
Just the bare spots. Chaulky siding that is not damaged is fine. Treat it as any other painted surface. After the repairs or bare spots have been sealed, then you can wash, patch, prime, etc. This means, all "end grains" where you're likely to caulk, seal that area too.

The top coat of paint can be water based and all the primer can be water based, AFTER all bare spots are COMPLETELY sealed. You are wise to stay away from a powerwasher on this, but you could use a hose, after it's sealed and caulked.
Hope this info is usefull.

PS. Chaulking is not a huge problem. I've cleaned many homes and have yet to see one that has been 100% de-chaulked. Controversial statement, but it's true. Get a cleaning product made to clean chaulky surfaces, an aluminum siding cleaner will work. Follow the directions and you'll be good to go.

Don't know if I ever mentioned it, I'm a journeyman, pro painter, over 20 yrs. experience.


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## AtlanticWBConst. (May 12, 2006)

joewho said:


> ....Hope this info is usefull.
> Don't know if I ever mentioned it, I'm a journeyman, pro painter, over 20 yrs. experience.


...If this is who you are, then I trust this more than anything I read anywhere...because it's about experience....:thumbsup:


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## joewho (Nov 1, 2006)

Members of the painting contractors forum put all our experience AND knowledge together. This helps me come up with answers for the diychatroom.

I learned from old timers and use experience as a basis, but the paint and stain industry changes all the time and plain experience isn't enough any more.

Thanks for the compliment.


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## Melomane24 (May 19, 2014)

I know that the thread is quite old, but I need an info. I have Masonite sidings that need to be repainted. The repainting job has been made some 8 years by me and my sons, but since then but bubbles have appeared. The sidings are ok, the problem is just the painting.

Joewho (do not know if he is still around) recommends to seal with shellac or zinsser shields the bare spots.

Which zinsser shields would be appropriate ? I thought for a time to BIN (shellac based) but the notice says for interior only. Or just use plain shellac, then water based primer ?


Jerry


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## chrisn (Dec 23, 2007)

shields is a wall covering primer, not for anything exterior, you want BIN


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## joecaption (Nov 30, 2011)

Blistering means there's moisture already trying to escape inside the siding.
There was class action law suites long ago and any recourse is long passed against Masonite.
Masonite is nothing more then ground up cardboard, adding a sealer over the surface and it's just going to stop the trapped moisture from escaping.
Use Zinsser 123 and latex paint.
Best way is to get rid of the Masonite totally.


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## jeffnc (Apr 1, 2011)

joewho said:


> Members of the painting contractors forum put all our experience AND knowledge together. This helps me come up with answers for the diychatroom.
> 
> I learned from old timers and use experience as a basis, but the paint and stain industry changes all the time and plain experience isn't enough any more.


Well said, sir.


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## jeffnc (Apr 1, 2011)

chrisn said:


> shields is a wall covering primer, not for anything exterior, you want BIN


Based on what the tech sheet says for BIN, it doesn't seem like it's approved for this sort of exterior use. All it says about exterior use is "Use BIN Shellac Base Primer to spot prime persistant bleed from knots and sap streaks before full surface priming with a water based or oil based primer."

I don't recall ever using BIN outside so I can't say I've seen it fail, just that it sounds like it's intended over natural wood only when it's going to be primed with another exterior primer before painting.


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## Jmayspaint (May 4, 2013)

jeffnc said:


> Based on what the tech sheet says for BIN, it doesn't seem like it's approved for this sort of exterior use. All it says about exterior use is "Use BIN Shellac Base Primer to spot prime persistant bleed from knots and sap streaks before full surface priming with a water based or oil based primer."
> 
> I don't recall ever using BIN outside so I can't say I've seen it fail, just that it sounds like it's intended over natural wood only when it's going to be primed with another exterior primer before painting.



Bin can certainly fail when used for a full prime on ext. I think partially because its not permeable. 
The can says interior / spot exterior. I think the idea is just not to use it as a continuous film so vapors can make there way around, and the most common use for it outside is stopping tannin bleed from knots. 


Hey, it's gotta be better than wallpaper prep coat


I believe I would use a water base primer like 123.


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## ToolSeeker (Sep 19, 2012)

If at all possible replace the siding. It is just my opinion but this siding, from your description, has already started to fail. If this is true any thing you do to paint it would be a waste of time and money. Also to replace the Masonite would really improve the value of your home. As much as I don't like vinyl siding it would be a great improvement over the masonite especially if the paint is blistering and peeling. Again just my opinion.


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## chrisn (Dec 23, 2007)

Jmayspaint said:


> Bin can certainly fail when used for a full prime on ext. I think partially because its not permeable.
> The can says interior / spot exterior. I think the idea is just not to use it as a continuous film so vapors can make there way around, and the most common use for it outside is stopping tannin bleed from knots.
> 
> 
> ...


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## jeffnc (Apr 1, 2011)

Well for Masonite, joewho says not to use a water based primer for spot priming bad areas because it just soaks it up and swells, etc. That makes a lot of sense to me, and the idea of spot priming first with BIN makes a lot of sense too. Just trying to figure out what Zinsser warrants it for.

Anyway, yeah - by far the best thing to do is replace the individual bad boards with HardiPlank. Hardie has specific replacements for all the Masonite profiles for this very reason. So you don't have to replace everything at once if you don't want to. The HardiPlank replacements will match the old. There are lots of siding repair guys who do this for less than an arm and a leg.

But as a super cheap option, just checking to see if the BIN idea would work well.


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## Will22 (Feb 1, 2011)

Masonite should be primed with an exterior grade primer ONLY- not Bin, Kilz, etc. Check the masonite for damage- the plies are adhered together with lignin, wax, and sawdust, and they come apart with age. Any acrylic top coat may be used as a finish coat.


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## jeffnc (Apr 1, 2011)

But we are talking specifically about spot priming, and I think joe has a good point. I don't see any reason to any priming at all of Masonite these days anyway - unless spot priming to save time/money and salvage a board.


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## ToolSeeker (Sep 19, 2012)

I tend to agree I kind of equate Masonite with particle board, once it starts to delaminate or gets wet and starts to crumble, there is nothing going to stop it. And I agree to wet it with water (latex) doesn't seem like a good idea.


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## Melomane24 (May 19, 2014)

I know that Zinsser BIN is not appropriate; I was asking for alternatives to other Zinsser offerings. I just want to get rid of these bubbles.

Thanks for helping.

Jerry

Edit: just saw the last posts; I repeat the the sidings are sound, no crumbling. They were installed in 1978.


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## cj133 (May 16, 2011)

Wow, I was upset and annoyed when I found out my bathroom ceiling was Masonite over plaster while installing a fart fan. I made sure I painted it with a good quality paint designed for bathrooms and to be honest most can't even tell it's Masonite.

Downstairs bathroom has it on the walls as well, I guess they thought it was an easy thing to cover aging plaster with.

I didn't like it on a bathroom ceiling, I can't even imagine having it as siding. Does it hold up ok if maintained?


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## jeffnc (Apr 1, 2011)

Well, yeah, I mean I have seen it hold up in some places, but then if you really paint and caulk something well, it won't get wet. But do you really want paper fiberboard protecting your house against the exterior elements? There's a reason there's a class action lawsuit against the stuff. If you ever held it in hands, you'd be surprised it ever got used at all. It's just common sense not to use stuff like that.


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