Materials Archive — Earthen Matter

Materials Archive Field Trips Projects Process & Techniques

Black Locust Burl

Common Name(s): Black locust, robinia, false acacia
Scientific Name: Robinia pseudoacacia
Distribution: Central-eastern United States, Europe, other temperate regions

Four sides of the same finished wood block.

This was the first burl that we collected. It came from a dead tree so drying was mostly done and therefore very quick. Only one section of the trunk was left and it had one big burl and a couple of smaller, unfortunately unusable ones.

On the inside it is very consistent, without voids. My personal favorite from what we have collected so far, I feel like it would harmonise very well with most blades since the wood texture has comparatively low contrast but still a very intricate figure.

BEECH BURL

Common Name(s): European Beech, Common Beech
Scientific Name: Fagus sylvatica
Distribution: Europe
Collection: Eindhoven´

This tree seems to rarely produce burls, but when it does they are very smooth on the outside and without voids on the inside, which makes working with it easy.
It’s somewhat prone to small cracks and warps while drying, and the very dense grain makes it dry especially slowly.

This tree is very prone to spalting, which is a fungus that grows within the wood and is manifested through black lines and differently toned sections. This specimen is lightly spalted, and most trees of this species that I have visited were also spalted.

Birch BURL

Common Name(s): Downy Birch, European White Birch
Scientific Name: Betula pubescens
Distribution: Northern Europe, Asia, Iceland, and Greenland
Collection: Eindhoven

This is a classic burl within the woodworking community. Some species of birch produce burls very commonly, sometimes with multiple pieces on a single tree. The burly wood figure with its golden colour is very visually striking.
This wood is more prone to warping than cracking while drying. It’s not very naturally dense so it dries relatively fast. Multiple pieces of this burl were collected and all of them are big in size when compared to other species.

This wood is pail when cutted but turns golden after it is finished.

Coticule, Latneuses

Name: Coticule, Latneuses
Provenance: Vielsalm, BE
Geology: Medium-grade metamorphic stone
Composition: Indurated clay, spessartine, quartz
Use case: Sharpening, Honing

Grit size: 2k-10k
Hardness: 4.5/5
Cutting speed: 5/5
Feedback: 5/5

This stone is known worldwide for good reason. It has excellent properties for a sharpening stone, better than most synthetic whetstones while being much more versatile, with great feedback.

Thick, paste-like slurry.

The versatility of this stone comes from the slurry. With thick, paste-like slurry the stone cuts very fast and behaves like a 2k synthetic stone. As the slurry becomes thinner the sharpening becomes finer, up to around 8k grit. Under running water it sharpens the finest, at around 10k grit, which is enough to comfortably shave hair.

Coticule, La Petite Blanche

Name: Coticule, La Petite Blanche
Provenance: Vielsalm, BE
Geology: Medium-grade metamorphic stone
Composition: Indurated clay, spessartine, quartz
Use case: Sharpening, Honing

Grit size: 1k-8k
Hardness: 4.5/5
Cutting speed: 4.5/5
Feedback: 4.5/5

Very similar to Latneuses, this stone is very versatile but works at a slightly lower grit range.
It contains more visible crystals which make the stone feel slightly less grippy. The difference is quite small.

Coticule, Latneuses Semi-Hybrid

Blue “hybrid” backside.

Name: Coticule, Latneuses Semi-Hybrid
Provenance: Vielsalm, BE
Geology: Medium-grade metamorphic stone
Composition: Indurated clay, spessartine, quartz
Use case: Sharpening, Honing

Grit size: 1k-8k
Hardness: 4.5/5
Cutting speed: 4.5/5
Feedback: 4.5/5

Very similar to regular Latneuses and La Petite Blanche. This stone comes from the same vein as Latneuses but the usable face captures a mixed composition of the normal Latneuses and its blue “hybrid” backside.

Slightly richer in quartz, it has less satisfying feedback but still works quite well. It has a nice blue and cream pattern, which might not mean better performance but makes for a more beautiful object. Personally, I think this holds some value as well.

Coticule, Latneuses, Hybrid

Name: Coticule, Latneuses, Hybrid
Provenance: Vielsalm, BE
Geology: Medium-grade metamorphic stone
Composition: Indurated clay, spessartine, quartz
Use case: Honing

Grit size: 6k-8k
Hardness: 5/5
Cutting speed: 3.5/5
Feedback: 3.5/5

Layered Gray Shale

These stones were at one point directly connected to the Latneuses, usually being present in the backside of Latneuses stones. The “hybrid” nomenclature was given to them in the past and I don’t know the reason. This layer of stone is composed of mostly crystalline quartz instead of spessartine and feels like it withstood slightly higher grade metamorphosis.

This whetstone feels hard, glassy, does not have the same versatility and is hardly suitable for sharpening. However, it is still a decent honing stone.These stones were found at one of the mines around Vielsalm. They were the only specimens found so there’s no way to know if they come from the mine or even the region. They could have been brought from somewhere else, like the Brazilian Shale that was also found at the same place.

Mediocre stones for sharpening and honing, and unsuitable for polishing. They looked interesting which is why I decided to bring them with me.

Name: Layered Gray Shale
Provenance: Vielsalm, BE
Geology: Metasedimentary stone
Composition: Indurated clay, quartz, others
Use case: Sharpening, Honing

Grit size: 2k-4k
Hardness: 4/5
Cutting speed: 2.5/5
Feedback: 3/5

Rouge du Salm / Lorraine

This stone is found at the Ol Preu quarry in Regné. Nowadays abandoned, this was the first quarry where the Coticule was extracted from. It is just a few kilometres away from Vielsalm.

When the quarry was still active, the Coticule was found in between layers of Rouge du Salm. Both stones were usually cut together but they were also sold separately since both are useful. This one is a bit less versatile and slightly slower than the Coticule. However, it is the stone with the best polishing I found so far. Great contrast between layers but still some visible scratches. Definitely worth another trip.

On a personal note, some years ago I found one of these stones while visiting my great-grandparents’ house in rural Portugal, alongside a straight razor from Solingen, Germany, in a box dated 1973. I was already making knives at the time but I had no idea what this stone was.

Name: Rouge du Salm / Lorraine
Provenance: Regné, BE
Geology: Medium-grade metamorphic stone
Composition: Indurated clay, spessartine, quartz
Use case: Polishing, Honing

Grit size: 5k-7k
Hardness: 4/5
Cutting speed: 3.5/5
Feedback: 4/5

Rouge du Salm, Soft

Name: Rouge du Salm, Soft
Provenance: Regné, BE
Geology: Low-grade metamorphic stone
Composition: Clay, spessartine, quartz
Use case: Polishing

Grit size: 5k-7k
Hardness: 2.5/5
Cutting speed: 3/5
Feedback: 4.5/5

This stone is also found at the Ol Preu quarry. However, no interest was ever shown towards it, since the stones mined there were meant to be used for sharpening and honing, not polishing. Coming from the upper layer, it was subject to less pressure (and time), which means it is a softer stone that wears out faster and produces a lot more slurry. These characteristics can be a detriment in some cases. But for smooth and visually striking polishing, they are fundamental.

This stone gave me the best polishing results so far. Not perfectly smooth but also not far from it, and with very nice contrast between layers.