Learned something new: Flaming

[Stonehenge]

I didn't think this would ever happen, but this morning, while watching one of those home and garden type shows, I actually learned something new.

A big patio project was going in that included the use of saw-cut Bluestone. Some of it was being used as bench seating.

Rather than chip away at the smooth-cut edges to give it a rough look, and potentially start to give it a splintered look as chips would certainly fly off in layers, they did something called 'flaming'.

They took a torch to the edges - the result was any small, smooth fragments of stone flaked off when they were heated, resulting in a textured face. Very slick, with little chance to damage the installed stone.

Anybody use that method? If so, what kind of torch, what kind of heat did you need to use to make things come out right without scorching the stone?


Jeff

[Lanelle]

I think some suppliers offer that finish. I recall seeing it listed for a granite supplier from up your way. I'm guessing that different stones require different temperatures or duration of treatment. Sounds like a good early spring test project with some waste material.

[Bladewizard]

Originally posted by lanelle
I think some suppliers offer that finish. I recall seeing it listed for a granite supplier from up your way. I'm guessing that different stones require different temperatures or duration of treatment. Sounds like a good early spring test project with some waste material.

[Bladewizard]

Similar to what I use to do in the glass business. The heat will cause the molecules in the stone to expand and thus creating any small pieces to fall off. I would think you would want to use a High flame and move it back and forth as not to actually burn the stone itself. Good Luck....And as Lanelle said, Practice makes perfect.......

[Stonehenge]

Lanelle, that sounds like a great idea.

BW, what you said makes sense. Thanks for the info!



Jeff

[agla]

Our masons do this all the time. We do it on cut and chiseled edges and sometimes to take out imperfections on a particular stone.

We actually did an entire pool decking out of thermalyzed bluestone this summer, so that it would match the bullnosed treadstock coping. It definitely changes the appearance of the stone from a smooth layered look to more of a finely pocked less reflective surface. It is very muted and creates an entirely different look.

[Stonehenge]

Agla -

First off, welcome aboard. Thanks for bringing your insight here. I know we'll find it helpful. :)

I'm glad to hear about this method - I had a project that I baulked on late last fall, because they wanted some bluestone, some of which was going to have the sawed face exposed, and I didn't like the idea of hammering on it, for fear of beginning to split open the striations.

What kind of heat has to be applied to do the job without burning the stone?


Jeff

[agla]

I don't actually do the work myself, but our guys use a propane torch I believe.

[Stonehenge]

My body tells me that the day I no longer touch the hand tools needs to be soon....

Propane torch sounds easy enough.

Thanks!

[PSUscaper]

hello,

I'm familiar with the technique discussed but not sure what size torch.

I know one thing.......a hand held propane torch won't work!!!! I've tried it and it doesn't quite work!

I'm thinking acetylene would do the trick.

One of the tricks is to not over heat. From what I've heard, you can easily overheat the stone and cause it to crack. I think it requires some practice to get the technique right.

When I asked my mason to do it on a set of treads that were already intsalled, he seemed reluctant to try as he was afraid of cracking the stone.

I have chiseled the edges before and agree that the torch has to be easier though.

steve

[Stonehenge]

Hmmm. That's interesting. The show I saw they were doing this after the pieces had been mortared together. Must have had some confidence in the amount of heat, that it wouldn't do any damage.

[agla]

I finally remembered to ask. Our guys use oxy/acetylene ( little on the hot side will pop off peices if not careful) or propane with oxygen. They run water over it as they do it.

[Stonehenge]

Excellent. Thanks for asking. :D

I wonder if the ambient temp has any effect on cracking?

[PSUscaper]

With all this talk about flaming, it got me thinking about doing a set of blue stone steps off of a house where the technique will be needed.

I've got the design together for a set of dry laid, blue stone steps that are going to be circlular off of a back set of sliding doors.

If sold, I will be cutting blue stone treads into circular treads to make the radius. A perfect oppurtunity for flaming.

I'm sub-mitting the proposal this weekend, so if it goes, I guess I will have to get some practice.

My welder friend will let me borrow his oxy-acetylene torch, so I figure I will try it out on a few scrap pieces and see how it goes.

It should be interesting!

I'm thinking goggles will be mandatory, and maybe his leather welding jacket.......not sure how well a flying piece of molting blue stone would feel popping off and landing on my skin.......

steve

[agla]

My boss can tell you. He took a good one several years ago. You may want to talk to your stone supplier and see if they can pre-cut and thermalize the treads for you or give you more accurate advice than my second hand "knowledge".

[dan deutekom]

I have used this technique several times. On a small piece a propane torch will work if you have the patience but you really need a little more heat. If I have a lot to do I use an oxy-acetelyne torch. You have to experiment to get the right timing because the temperature of the stone does make a difference. I also like to use a little water if the stone is "stubborn" because the cold water on the hot stone flakes of chips well. Be sure to wear eye protection because little flakes of stone can pop off in any direction.

[BRL]

Would this also work with other stones\concrete\etc.? I a have acetylene torch & this sounds fun & better than chiseling stuff in those cases.

[agla]

It is my understanding that acetylene is too hot and will cause the stone to pop in your face. Different stone will pop with different heat I am told.

[BRL]

Just got a new price catalog from the main stone\paver\construction materials supplier here. It had this little section about this thread in there:

2.) What is "thermal finished" bluestone?
Answer: The term thermal finish describes the process in which blocks of bluestone, after being sawn into specific thickness, are wet down and burned with a high temperature torch. The water penetrates the sawn surface of the stone. When the torch is passed over it the heat agitates (boils) the moisture causing the stone to "pop", creating a textured but smooth surface. The vasst majority of "thermal finish" bluestone is without ridges, indentations, and other natural appearances, that would normally define it as natural cleft.

[Stonehenge]

:cigar: :thumbup:

[my big dog]

re -visiiting this thread from long ago. I have approx. 40lf ft of bluestone to thermalize any one else have some helpful tips?

[dan deutekom]

I have actually switched from oxy-acetyline to oxy-propane and it seems to work well. Just takes a little bit of experimenting to get the right heat. Watch your face! The little bits of popping rock really hurt.

[natural12]

I have done this before with an oxy-acetylene torch. Be sure to use water on the stone. Also, where protective clothing.

You could also rough the edges with a good carbine chisel. They cost close to $100 but their worth it. Depending on the thickness of the stone it is sometimes hard to chisel the center area. You could torch the middle area to save time.

Here are some columns we did with torched bluestone.

[my big dog]

Any rough thoughts on how long this may take bluestone is 1.5" thick sawn cut. What will happen if too much heat is added?

[Stonehenge]

@Nat12 - Those are gorgeous!

[my big dog]

Thermalized bluestone edge today. Used map gas and oxygen mix worked well burned through a lot of oxygen though.

[natural12]

Thanks stonehenge :)

[Stonehenge]

Were the stone thin veneers or were they relatively thick? Also, did you just build CMU columns and mud these onto them? I love the variation in color - I don't know if we'd be able to get that kind of variation here.

How'd you anchor the iron?

[natural12]

The stone is in the category of building stone. Probably 4-6 inches thick. We first built the base out concrete block. I think 8"x8" block for the columns themselves. The stone is mortared on the backside with maybe a little in between.
I believe this stone was called Arkansas moss rock. It was very hard - I will never use it again. My wrist was messed up for about 6 months. But I picked it because it was gorgeous stone.

The iron worker used a core bit to drill holes for his mounts to support the gate. Also used some glue for extra grip.

Recently for gates we have had supports fabricated that are set into the footing and extend up thru the core. More work but if the gates are substantial then it is necessary. I will post some photos of this shortly.

Mike

[mant]

I have been flaming for quite awhile and have watched the big granite sheds flame alot of material quickly. The large bluestone sheds use the same technique, they send the piece on a conveyer belt through a flaming station where there is maybe 6-10 torch heads running at once (oxy-acetyline), flaming the material as it moves through, the speed varies depending on the material and they all use a rosebud tips. Granite flames much better than bluestone. They usually flame the product first then cut it to size after, the reason being the edges can be a little tricky, you sometimes lose part of the edge especially flaming in the field (watch those edges). Flaming in the field sometimes scares me especially bluestone, I have lost parts of the edges due to the makeup of the stone and the proper flame temp. Then what do you do? Take it out and start over!
I once did a 200 sq ft patio out of granite skins(the first and last cuts off a granite block), the finished side was smooth from the wire saw and the arcitect decided it was to smooth so we had to flame it in the field. 40 hrs later it was done! We used what is called a Jet Stick(a water cooled flaming tool). It uses propane or acetyline and O2, we used propane and liquid O2. The liquid O2 was because the jet stick really uses up the O2 and that was cheaper and we were able to get a big tank. The only drawback to the jet stick is it sounds like a jet engine when working, but it was amazing, it could burn a hole right though the stone! The college kid I had working loved it, did it all himself, 8 hs a day for a week!! Maybe he has a new profession, I bet they don't teach that in college!

[Prosno]

I've flamed bluestone treads for steps probably for ten years now, its not hard just take a hose and soak edge of bluestone, then I hit the edge with an Oxy/acet torch and walla! its done.
A four foot tread takes me about two minutes and thats to wet it and flame it.