# Flagstone "Bruising" - quartzite



## Havoc501 (Feb 10, 2015)

I am currently installing some flagstone on top of a concrete slab in our backyard, and have some "bruising" that has occurred on some of the pieces.

Ideally, I would like to cut some of the pieces with a saw, and then do a light chisel on the top edges so it doesn't appear to be a saw cut when mortared in place. On a "normal" stone, there doesn't appear to be any issues with this. However, the flagstone I am using is a quartzite stone, which is very hard and very dense. After the stone is cut with the saw, the cut edge appears to be a kind of "powdery white" type of color. And if I hit the edges with a chisel, it also produces this "powdery white" surface in the chipped area. From what I gather online, this is called "stone bruising" - at least in the stone sculpting business. 

I have used a wet diamond polisher on a sample piece to polish the edge of the saw cut area, and it brings the coloring back (similar to how granite countertop installers polish counter tops and edges). However, this also makes is VERY smooth. 

I don't really need to bring the stone coloring back to the saw cut edges since they will be in the mortar, but I do want to bring the coloring back to any chiseled area. So, what I wanted to see was if anyone else has come across this type of issue and if there is some kind of remedy to get rid of this stone bruising.

Thanks. Any help would be much appreciated.


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## oh'mike (Sep 18, 2009)

Be patient---we have several experienced pros--and a bunch of knowledgeable DIYer here---


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## jomama45 (Nov 13, 2008)

The term must be from he stone sculpting world, because I've never heard of it.

With flag, really any natural stone, we always cut 50-80% of the way through the stone from the backside, and either chisel or simply hammer the waste off from the front side to leave a more natural look. If I understand what your reffering to, it's not really a big issue either, as the mortar will likely cover a little of the top edge of the stone, and it's so un-noticeable typically that it's a non-issue.........


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## Bud Cline (Mar 12, 2006)

Have you considered flaming it?


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## Havoc501 (Feb 10, 2015)

Jomama45, for the most part, no, it will not be an issue. However, we are using flagstone for some steps, and it will be noticeable in that area, because there will be an exposed edge. Also, I would like to try and chisel or hammer the edges of the stone to soften the straight cut on some of the edges. However, whenever I try and hammer the edges, anything that chips off creates these white marks and not the stone's natural color.

Bud Cline - What is the though behind flaming it? Any specific torch type or flame temperature I should be looking for?

I'll try and grab some pictures tonight of some of the areas I am talking about to give a visual for everyone.

Thanks for the responses guys!


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## Bondo (Dec 8, 2007)

Havoc501 said:


> Jomama45, for the most part, no, it will not be an issue. However, we are using flagstone for some steps, and it will be noticeable in that area, because there will be an exposed edge. Also, I would like to try and chisel or hammer the edges of the stone to soften the straight cut on some of the edges. However, whenever I try and hammer the edges, anything that chips off creates these white marks and not the stone's natural color.
> 
> Bud Cline - What is the though behind flaming it? Any specific torch type or flame temperature I should be looking for?
> 
> ...


Ayuh,.... Are these stairs, Inside, or Outside,....

In my limited experience, the stone will oxidize, 'n return to it's natural color,...
More quickly outdoors of course,....


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## Havoc501 (Feb 10, 2015)

Outside. Some of the stone has been cut since October and it looks the same as the stone that was cut two days ago.


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## Bondo (Dec 8, 2007)

Ayuh,... Donno yer stone, but it does take Time,....

think years, vs: months,...


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## ZZZZZ (Oct 1, 2014)

Don't know if this will help the situation or make it worse, but you can try applying a stone sealer-type product to the edge and see if that changes the color more to your liking. From what I've seen, it makes the color darker.

Try it on a sample or two.


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## jomama45 (Nov 13, 2008)

Havoc501 said:


> Jomama45, for the most part, no, it will not be an issue. However, we are using flagstone for some steps, and it will be noticeable in that area, because there will be an exposed edge. Also, I would like to try and chisel or hammer the edges of the stone to soften the straight cut on some of the edges. However, whenever I try and hammer the edges, anything that chips off creates these white marks and not the stone's natural color.
> 
> Bud Cline - What is the though behind flaming it? Any specific torch type or flame temperature I should be looking for?
> 
> ...


The secret to exposing good edges at steps is to start with the steps, and use the best natural edges you have to work with. It's highly unlikely you're going to chisel the edges of typical flagstone to an acceptable finish, unless you've done it for a living for 1,20,50 years. TO give you an idea, I've been a mason for about 20 years, and I won't bother attempting to chisel flagstone that will be exposed on the edge, and I have a number of different carbide chisels that range between the $150-200 price range.

So, I'd highly recommend starting with the treads for the steps, and using the balance of the material for the flatwork. If you re-read my earlier post, you'll see that we always saw from the back side and smack the frontside off to eliminate lines that are too straight and un-natural.

Lastly, when it comes to "flaming" of the edges, I doubt it will work, as it's only works with a very limited amount of types of stone in my experience. New York Bluestone is the only stone I've had success at dressing with fire. And even then, flaming can be relatively dangerous, and I don't suggest a DIY'er attempt in........


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## jomama45 (Nov 13, 2008)

Havoc501 said:


> Outside. Some of the stone has been cut since October and it looks the same as the stone that was cut two days ago.


This stone has likely been taking on it's color under the Earth for hundreds of thousands of years,,,,,,,,,,,,,,,:whistling2:


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## stadry (Jun 20, 2009)

you might try propane using a rosebud tip,,, we successfully used it on vt, ga, va, & sd granites + pa bluestone,,, i never knew we had ny bluestone - all the bluestone quarries we had were just s of the ny/pa border


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## Havoc501 (Feb 10, 2015)

Thanks for all the reply's guys! Here are some pictures of what I have been talking about. Unfortunately, our contractor has already done the steps, but I agree... I asked them after they did it why they did not use a natural edge for the steps. However, in addition to the steps, I have some exposed edges that meet up to a grass area, as well as some exposed edges that meet up against a couple of planting areas.

*Picture#1:* Shows the white "chip" marks on top of one of the stones. There is an obvious answer of "just replace the stone," but I have several that are like this, and I'd like to know if there is a way to fix these?



*Picture#2:* Tried to get a closeup of one of the white marks.




*Picture#3:* Stone with the natural edge.




*Picture#4:* Stone with a saw cut edge. This shows the "white" I was talking about.




So, if you notice in *Picture#4:* some of the cracks/edges that you see that will eventually have grout in them are saw cut edges. My thought was that in an effort to create a "softened" edge, rather than an obvious saw cut edge, I would like to be able lightly chisel, hammer, or whatever it takes to the top, exposed edges that you would see at the grout line.

Edit: I should also note that the "white marks" in picture 1 are similar to what happens if I try to use a chisel on any of the edges.

Thanks for all the helps guys!


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## stadry (Jun 20, 2009)

we called those ' stuns ' & never did figure out how to disguise 'em :no: that's why we were always careful moving stonework,,, as i recall, stonescrapes, tool marks, & stuns will outlast any stonecutter :yes:


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## Bud Cline (Mar 12, 2006)

stadry said:


> we called those ' stuns ' & never did figure out how to disguise 'em :no: that's why we were always careful moving stonework,,, as i recall, stonescrapes, tool marks, & stuns will outlast any stonecutter :yes:


Sandblast them.:yes:


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## stadry (Jun 20, 2009)

we did but it was like pouring white ink onto not-so-white ink :furious:


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## jomama45 (Nov 13, 2008)

If you're talking about the white blotches on the surface in picture #1, it appears to be mortar/dirty mortar water stains to me.

As for minimal chipping on the edges, I'd try tapping on the edges with a brick hammer (perpendicular to the edge so you don't break the stone) to get a little irregularity. This is exactly why we always saw from the back side, partially, and snap the front off. Overall though, it shouldn't make a big difference after it's grouted.

As for the edges, you're never going to get an human altered edge to match the rest of the virgin material, which is why we always use a natural edge. You can try "flaming" the edge, but you could break a few, or have no luck at all. If you want them to attempt flaming, I'd highly recommend doing it before the stone are permanently set.


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## Havoc501 (Feb 10, 2015)

Thanks for the info guys. Jomama45, I get what you're saying about partially sawing and snapping the rest of the way. I had seen videos and people's "how to" articles talking about this kind of method. However, I can't really dictate to my contractor "means and methods" on how to do something. And I've made this suggestion to them in the past.

Anyway, the idea of using a brick hammer is interesting. I'll probably give that a try. If I decided to try flaming the edge, or those white spots, is there any type of specific tool I should use? Would a propane torch suffice? One of the previous comments mentioned use of a rose bud tip, but aren't those typically for an oxy acetylene setup? Or can I use something similar for a propane torch?


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## jomama45 (Nov 13, 2008)

I've tried a rosebud on my oxy/ace torch, and IIRC, it wasn't hot enough to do a good job. Here's a video of exactly how I do it, except I would never wear shorts and tennies while doing it:

https://www.youtube.com/watch?v=T23O3Os6zRg


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## Bud Cline (Mar 12, 2006)

It can be done with propane using a long handled "brush-burner-torch" so you can keep your distance in the event a stone explodes. Once the stone is heated pour cold water on it. Be careful, the stones can pop and crackle and will throw off particles. Wear safety glasses at the very least.


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## stadry (Jun 20, 2009)

looks like a reg cutting torch tip to me :whistling2: rosebud's about 1 1/2" diam & usually mounted on a 30" stem pipe - just propane - no oxygen,,, odd wearing welding gloves for cool handle yet shorts & sneaks :huh: what's up w/that ?


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