Knapping is an ancient shaping technique traditionally associated with materials such as flint, chert, and obsidian. Today, the same basic principles are also used with modern glass, allowing makers to explore a much wider range of colors, transparency, and visual effects.
At RELIQ, I work with both obsidian and glass when creating handcrafted collectible blades. Although the shaping process can look similar from the outside, the two materials can feel very different once you start working with them.
So what is actually different between obsidian knapping and glass knapping?
What Is Obsidian Knapping?
Obsidian is a naturally occurring volcanic glass formed when lava cools rapidly with very little crystal growth.
Because of its glass-like structure, obsidian can fracture in a predictable curved pattern known as a conchoidal fracture. This is one reason it has been used for cutting tools and decorative objects for thousands of years.
When obsidian is knapped, carefully controlled impacts or pressure can remove thin flakes from the surface.
The resulting blade often has:
A deep glossy appearance, strong contrast between flake scars, sharp-looking geometric textures, and a distinctly natural character.
Black obsidian is probably the most recognizable variety, but different types of obsidian can show gray, brown, reddish, or reflective effects depending on the material.
My Experience With Obsidian
I first started working with obsidian around 2021, when a friend gave me a piece to experiment with. The moment I saw how it looked after shaping, I was amazed by the depth, reflections, and natural texture of the material.
For me, one of the most difficult things about working with obsidian is its brittleness and unpredictability. A piece may look perfectly stable, but small differences inside the material can sometimes cause a fracture to travel farther than expected. This becomes especially challenging when the piece is already thin, because there is much less room for error.
Among the different types I have worked with, silver sheen obsidian and red obsidian are some of my favorites. Because they contain natural colors and reflective effects, the surface can reveal completely different patterns depending on the angle and lighting.
That is one of the things I love most about obsidian — sometimes the most beautiful effects are created by nature itself.
I have also had serious failures. On one piece, I made the blade too thin during the process, and it eventually broke. It was frustrating at the time, but failures like that taught me much more about the material than a successful piece sometimes can.
【A failed obsidian piece from my earlier work. I made the blade too thin, and it eventually fractured — an experience that taught me a lot about working with the material.】
What Is Glass Knapping?
Modern glass can also be shaped using many of the same principles used in traditional knapping.
Depending on the type, thickness, and composition of the glass, it can produce clean flake scars and highly visible surface patterns.
The biggest advantage of glass from a design perspective is variety.
Instead of being limited mainly by naturally occurring stone colors, glass can be produced in:
transparent finishes, translucent colors, pale blue, pink, red, black, opal-inspired finishes, and many other visual styles.
For collectible pieces, this creates much more freedom.
A traditional-looking knapped form can suddenly take on a completely different character when made in light blue, translucent pink, or an opal-style finish.
This is one of the reasons I enjoy working with glass.
Obsidian vs Glass Knapping
At first glance, obsidian and glass may look very similar because obsidian itself is a form of natural volcanic glass.
But from a maker’s perspective, there are several important differences.
Appearance
Obsidian usually has a more natural and primitive visual character.
The dark surface makes each flake scar easy to see, especially under directional light.
Glass, on the other hand, offers much more control over color and transparency.
A pale translucent glass blade can look almost completely different depending on whether it is photographed indoors, under sunlight, or against a dark background.
For display pieces, that variation can become part of the design.
Material Consistency
Manufactured glass can sometimes be more visually consistent because its composition is controlled during production.
Natural obsidian may contain small variations, inclusions, internal stresses, or differences in thickness.
That does not necessarily make one better than the other.
It simply means that every material has its own behavior.
And when working by hand, learning how a particular piece reacts is often more important than the name of the material itself.
Color
This is where glass has a major advantage for modern collectible design.
With glass, I can experiment with combinations such as:
light blue blades with colorful handles, translucent pink blades, pale red finishes, clear or milky white designs, and opal-inspired visual effects.
Obsidian has a much stronger natural identity.
When I want a piece to feel darker, more primitive, or closer to traditional stone craftsmanship, obsidian is often the obvious choice.
When I want something more experimental or fantasy-inspired, glass offers much more freedom.
Which Is Harder to Knapp?
There is no single answer.
The difficulty depends on the specific material, thickness, shape, internal stress, and the technique being used.
Some pieces of glass can respond very cleanly.
Others can behave unpredictably.
The same is true for obsidian.
For me, the biggest challenge is not simply hitting the material.
It is controlling:
where the flake begins, how far it travels, how much force is used, the angle of contact, and how much material remains after each step.
A small mistake can completely change the final shape.
The Biggest Difference I Notice Between Glass and Obsidian
In my own work, one difference I notice is that pink glass often makes the area I am working on easier to see. The lighter, translucent color makes certain surface changes more visible to me during the process.
Obsidian feels very different. Its darker surface creates stronger contrast and a deeper, more primitive appearance, especially under directional light.
I have worked with obsidian more than any other material, followed by glass and synthetic opal materials. Because I have spent so much time with obsidian, I have gradually become more familiar with the way different pieces behave, although the material can still surprise me.
Glass gives me more freedom with color, while obsidian gives me something that is much harder to reproduce artificially: the feeling that the material already has its own character before I begin working with it.
How People Reacted to My Obsidian Work
Obsidian has also been one of the materials that received the strongest reactions from my community.
Whenever I shared finished obsidian pieces, people often described them as “cool,” “beautiful,” or visually striking, especially when the natural sheen became visible under light.
One of the things I enjoy most is sharing a finished piece with the community after spending a long time working on it. Seeing people respond positively to the texture, shape, and material makes the process feel worthwhile.
Over time, those reactions also influenced the direction of my work. They encouraged me to continue experimenting not only with obsidian, but also with colored glass, synthetic opal materials, and more modern fantasy-inspired designs.
For me, that feedback is important because RELIQ did not develop in isolation. Much of what I make today has been shaped by years of creating, sharing, receiving feedback, failing, and trying again.
https://reliqshop.com/products/handcrafted-obsidian-knife-knapped-collectible-blade
Related Guides and Collections
Start with our guide to knapping, then explore glass knives and daggers or obsidian-style display blades.
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