Stone "texture" and how I polish to get the best finish possible

[Redrummd]

I often write, talk and chat about "texture" in stone. I will comment that a specific knife has a bit worse "texture" or less "texture" than others I have done with the same stone. Depending on the stone the "texture" I am referring too may be of different types too which does complicate matters.

So, I thought I would start a thread about this as I personally find it very interesting and my attempts to defeat the causes and appearance of "texture" is a really big aspect of my artistic sense and drive to get the best results from any given stone I use.

I think the best way to explain this is to compare natural stone to another natural material everyone can look over - wood. In wood "texture" can be the big structures that show such as knots and checks. These would compare to pits, vugs and lines in stone. In stone these are caused by many variable events but mostly by deposit of dissolved minerals over periods of time up to millions of years or fast moving events such as earthquakes, volcanic eruptions or floods. These natural occurring structures in stone allow for the deposit of new layers or lines that lead down into the stone that feed in new minerals that affect color, designs or even hardness.

End cut grain is another aspect of wood where the growth rings have different structures and harness. In stone these can be lines or rows of tiny pits and again are conduits that allow mineralization of things such as layers of mud that become silicate stones such as Agates, Jaspers and even Flint.

On quarter sawn wood you get grain that allows the surface to appear to be a glossy polish but at an angle to the light you can see a lot of "texture" that is the grain of the wood and even tiny voids if the wood has been finished with an oil finish. In stone this is very common if you look close and at the right angle.

 

[Redrummd]

Jade is a stone that can have a huge amount of texture or practically none depending on the size of the fibers that the Jade is composed of. Most Jade that is sold commercially is treated with hard waxes while the Jade is hot so that it will take a glossy polish. I am not set up to do that and putting a finished knife into a vat of hot water and then into a vat of hot wax would probably not be a good idea! I have become very good at getting a very good polish on Jade with Diamond wheels, Fabulstre and ZAM but sometimes I get more of a shine than a polish. I just note that when I describe the Jade I use. The usual way is to define the better grade and polishing Jades as fine grained Jade or if very top grade I refer to it as "gem" or "jewelry" grade Jade with gem and jewelry meaning the same thing.

Here are a few photos of a beautiful but very hard to polish Jade from here in Washington State. I refer to it as having a lot of "texture, difficult to polish and taking more of a shine than a polish.

 

[Redrummd]

While I used wood as my example of another natural material with a lot of texture I thought it would be interesting to show how this texture can carry over through the petrification process. In this example I have sanded Petrified palm from Indonesia through 600 grit. That is the point at which I dry off a knife and look at the stone for any pits that I can fill with a UV stable, museum grade polymer, Hxtal. You can see in the photos that I started to fill the pits before I thought to take a couple of photos.

Filling these small voids really improves the final polish results. I estimate that this step reduces the pits by about 80%. I cannot get them all as after filling I still need to re-sand at 600 and then 1200, 3000 and 8000 grit before I get to the polish. The pits that are uncovered in these last sanding stages are usually very small and on most knives cannot be seen without specifically looking for them at an angle in a bright light so the polish can be a mirror polish. This extra step I take to get the best polish I can takes a lot of time to do as I need to use a toothpick and fill each pit. It then takes about four days to harden completely.

This knife is one I am currently working on as a custom request and will be stunning. Look at all of the metal flecks in the slab! Both slabs have this Pyrite scattered through the black agate inside the outer bark area. WOW!

 

[Redrummd]

The next type of texture I deal with is "lines" in stone. Lines are usually the point at which minerals deposit in stone. These minerals are usually the most colorful part of a stone. In a lot of stone composed of multiple components these lines are often found at the point where two different minerals meet. The copper based stones I use often have Malachite, Shattuckite, Chrysocolla, Cuprite, Chalcocite and Quartz in them so they tend to have a lot of these lines.

Here is a photo of a slab of one of these copper stones. It looks absolutely solid.

 

[Redrummd]

Now, to "see" these lines I get the slab wet. These feed lines will adsorb water more easily than the rest of the stone that the slab is made of. As the slab dries the lines hold water and they show up as dark "lines" in the slab. Here is a photo of the same slab as it dries that shows the lines.

 

[Redrummd]

Filling these lines results in both a stronger stone that will survive the roughing out grinding to make preforms and for me to use these most colorful areas of the slab and still get a nearly perfect polish. I heat the slabs to about 120 to 140 degrees under a shop light. This tends to both open up the lines and to make the Hxtal thinner so that it will wick into the lines better. In fact over a period of five to 7 days the Hxtal will wick all of the way through a 1/4 inch thick slab and completely seal most of these lines.

Here is a photo of a slab I covered with Hxtal and the back of the slab a few days later where you can see how the polymer wicked all of the way through.

If you look carefully you can see that the bright blue line in these slabs is a central feature of one of the knives I show in the next post.

 

[Redrummd]

I am very selective in the stone I use so the need to fill pits, vugs, lines and other "texture" is not something I need to deal with on every knife. Here is a photo of the group I am currently working on. Only the four knives on the piece of wood needed any "texture" dealt with after the 600 grit sanding.

I could leave the "texture" as a natural part of the stone but I artistically cannot stand not getting my polish as close to perfection as I am able to do and as knives are often used, these same natural structures will fill with dirt, oil, wax and just plain gunk and potentially look terrible.

 

[Redrummd]

The next "texture" I have photos of is the type found in Dinosaur Bone. The cell walls that were bone are usually not the solid agate that fills the inside hollows in the bone. In addition Dinosaur Bones has the same fill lines other stones have that may be cracks that occurred as the original bone dried in the sun or as a result of geological events such as earthquakes and volcanic eruptions.

Here are a couple of pieces photographed head on first.

 

[Redrummd]

Here are the same pieces photographed at an angle to show the pits and lines. I deal with these just as I do with the lines in the example with the copper minerals. I heat the slabs and allow the polymer to soak through the slabs which allows a much finer polish to be done on a knife scale as compared to the polish on these two pieces I have polished but not yet slabbed for use on knives.

 

[Redrummd]

One other type of texture that is found in stone is caused by the differences in hardness of the components. This "texture" shows very well on Dinosaur Bone and I refer to it as the alligator skin texture.

 

[Redrummd]

This is all I have for now on this thread but feel free to ask questions as I can take photos or explain in more detail.

 

[testdw]

Mike,
Thanks for all the "Texture" info. I had no idea how much time and expertise that you invest in stones with texture. You are the best in the industry and this is another example why this is true. I really appreciate the effort that you invest to attain the best possible piece of art/knife.

Your current working group is VERY NICE.

Dennis

 

[Redrummd]

Dennis,

I am glad you like the group as three of them are knives you requested! The Palm, Lapis Lazuli and the Chrysocolla veined piece from Buckskin Mt. AZ.

 

[hohenstreetroa]

All,
Once again I was privileged to visit Mike's shop. I picked up a couple knives I purchased and checked on the Harquahalla Shattuckite custom 110 Mike is creating for me. Regarding the "texture" discussion... all I can say is what texture? Although I have a few knives with some "texture", once Michael works his lapidary "magic", there is rarely much noticeable texture. Dennis, your palm knife has almost NO texture now that Mike has done the final polishes. What you will notice in the pictures is the "glitter" that you see! SUPER COOL! I have several of these Indonesian palm knives, but NONE have the "sparkly" effect that yours has! Phenomenal knife - you will be amazed to see it in hand!

Jade Kitchen set in the works - final stages...

Note the "glitter" effect in this Indonesian petrified palm caused by the silver metal flecks of... pyrite?
This is the same knife Michael pictured above where he discussed filling the pits with Hxtal.

Here is the REAL "texture" in Michael's shop... a.k.a. Ginger, the ferocious (or not so much) guard dog!!

 

[Redrummd]

Here is another sort of texture. It is a open large grained stone texture. Some Jades, Dumortierite and this Rhodonite show the grain pretty much no matter what I do to the stone. I have seen these stones all take a smooth polish when a hardwood spool or cork is used to get the final polish but those methods are not possible on a knife. I usually note that stone with this difficult "texture" takes more of a shine than a polish. It is interesting to note how good the shine is and that this "texture" is not easily photographed. I need to take the photos that show the texture on an extreme angle to the light for the texture to show in a photo.

 

[HwangJino]

Very interesting read!

Beautiful handles.