# Painting cultured limestone



## New2DIY (Jul 1, 2008)

Our fireplace mantle and hearth is made of white cultured limestone that is not sealed. I'd like to paint or stain it a deep chocolate brown. I want it to have some color variations so that it doesn't look like a piece of painted styrofoam, so I was thinking of using a colorwash technique with three different colors. Has anyone ever painted cultured stone? Would I have to use special high-temp tolerant paint because it's a mantle and hearth? Would a concrete stain be a better choice than masonry paint? Tips, suggested tools, techniques, and products would be very helpful. I'm thinking of finding a place that I could get a few pieces of cultured limestone to practice and experiment on, but I don't know where I would find that. Thanks for taking the time to read this.


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## Nestor_Kelebay (Jun 17, 2008)

No, don't use a "masonary paint".

A masonary paint is a latex paint that prevents liquid water from passing through it, but still allows individual H2O molecules to pass through it easily. The way it does this is that if you imagine each of the latex resins to be a long wire scrunched up into a ball, the spaces in that scrunched up wire are larger than the effective diameter of a single H2O molecule, but smaller than the average distance between H2O molecules in liquid water. This, individual H2O molecules can pass relatively easily through a masonary paint, but liquid water will not (cuz H2O molecules in liquid water will be attracted to one another, and will stay together as a liquid). When you paint such a paint over a brick wall, it keeps rain water from getting into the masonary units, but allows any water inside the wall to dry up by evaporating out through the paint. That keeps the wall as dry as possible to prevent damage from water inside the masonary freezing.

If I were you, I would first try to clean that limestone mantle with an acidic cleaner like CLR, or a phosphoric acid based toilet bowl cleaner. that will dissolve the top millionth of an inch of limestone, which includes all the dirt, and will show you what that mantle looked like when it was new. I think if you see it clean like it was when it was new, you won't want to paint over it.

However, if you still want to decorate it, consider using a concrete stain maybe.

I don't have a fireplace, so I don't know how hot mantles get when there's a fire in the fireplace. If they get good and hot, I'd use a high temperature paint made for painting bar-b-ques.


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## New2DIY (Jul 1, 2008)

Here's a picture of the fireplace in case that helps anyone:


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## slickshift (Aug 25, 2005)

Hmmm...don't believe I've ever had to seal one of those
I agree a nice faux would be cool
It does have that Styrofoam Thing going on

No need to high temp paints for this

After sealing, you want to base coat then faux

Sealing the mantle ....I'm not sure
I'd suggest contacting your local Paint Store (not Big Box) and asking
Or better yet, contact Benjamin Moore or Sherwin Williams directly through e-mail or phone call


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## Nestor_Kelebay (Jun 17, 2008)

New2DIY:

I know a little bit about limestone because I have actively been trying to get high calcium carbonate limestone from various sources for use as a pH neutralizing media for a high efficiency condensing boiler.

You say this is a "cultured" limestone. I really don't know what that means. Does it mean that the limestone is man made?

In limestones, the higher the calcium carbonate content, the whiter the limestone. From your picture, that pure white limestone would be 100 percent calcium carbonate, which is really very rare in nature. There are only a few places on this earth where limestones of more than 98% calcium carbonate can be found.

If that limestone is natural, I'd very much like to know what the name of the quarry is that it came from, and the name and phone number of the company that operates that quarry.


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## New2DIY (Jul 1, 2008)

Nestor:
That is man-made limestone that I was told is some sort of composite material that was poured into a form to create the mantel. It definitely gives off dust like real limestone, but it isn't a naturally occurring stone.

Slickshift:
So I can just use regular interior latex to paint the fireplace?


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## slickshift (Aug 25, 2005)

New2DIY said:


> Slickshift:
> So I can just use regular interior latex to paint the fireplace?


I forget the actual "top" temperature a premium paint can handle, but needless to say even the wall behind a wood stove does not need any special paint
-which is basically why I've forgotten the temp....it's mostly a "non-issue"

I would recommend a premium waterborne enamel as it does get a fair amount of traffic and handling, but yes

The hearth itself, I don't recall painting one of those
Usually those are brick or stone
Makes sense as that would get the most abuse and heat


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