What Is Concave Engraving? Definition, Uses & Procedure

Concave engraving is one of many ways of carving a design into your material of choice. The tool for this type of engraving follows a path that carves the design or text into the surface. The design is thus concave compared to the surrounding material. By carving into the material, you’re able to produce an aesthetically pleasing three-dimensional effect. 

Concave engraving finds relevance in a range of materials such as stone, glass, and metals. It is common in jewelry since it allows you to create intricate designs on pendants, rings, and other accessories. The process of concave engraving usually involves a specialized tool known as a graver. 

One type of graver tool is called a burin. It can carve into the surface of many types of material. More sophisticated methods like laser engravers function as automated tools and do the job with a greater level of precision and speed. This article will define concave engraving, explain its process and materials, list examples, and examine the industries that use it.

What Is Concave Engraving?

Concave engraving is a method that requires the removal of material from the surface of a workpiece to create an indentation that is curved inward, recessed, or otherwise hollowed out. It is a popular technique among metalworkers and jewelers. They use this method to create intricate designs on the surfaces of metals. Historically speaking, the practice of concave engraving dates back to ancient times. It was employed by artisans to create decorative patterns on precious materials like silver and gold. 

Concave engraving — the most basic type of engraving — originated independently in both Northern Italy and Germany in the mid-15th century. Silverware, decorative plates, pendants, rings, and earrings are all classical targets for engravers. Concave engraving as a method for carving a pattern into the surface of a material has come a long way. Today, it is often done with modern tools such as CNC machines or laser engraving machines. These methods are highly efficient and produce more complex designs compared to traditional methods.

What Is the Process of Concave Engraving?

The process of concave engraving starts with the preparation of the material. The material is cleaned or polished to ensure a smooth and even surface. The design is then carved into the material either manually or via an automated machine. 

To manually engrave, an engraving device such as a burin is used to cut into the surface of the material following the design’s pattern. Its appearance is determined by the shape and depth of the channel cut into the material. An engraver must be both skillful and patient because the process can be laborious and time-consuming. The manual process of engraving must be done in such a way that the pressure and angle of the graver are carefully controlled to achieve the desired effect. This process is very different from more modern, automated ones. 

A computer-controlled laser machine will not only get the work done but also does so in an efficient and timely manner. The laser should have enough power to remove whatever material you’re working with. The result is a three-dimensional pattern with the engraved area being cut lower than the surrounding surface. Once complete, the workpiece may need post-processing such as polishing or plating. This will enhance the durability and appearance of the design.

What Are the Materials That Can be Used for Concave Engraving?

Some common materials that are used for concave engraving include:

1. Glass: Glass is delicate, so it demands skill and precision from any engraving process. A wide variety of glasses can be engraved, such as: wine glass, mirror glass, and crystal glass. Concave engraving is done using a sandblaster or laser engraver with the workpiece set in a rotary attachment so it can be maneuvered during the process. This makes it possible for the lettering or designs to be engraved around the object, even if it is not flat.
2. Metal: Metal is an ideal durable target for concave engraving. Engravers commonly use metals like: copper, gold, brass, and silver. The process requires specialized tools which range from handheld burins and chisels to more sophisticated and mechanized tools such as laser engravers or CNC machines. 
3. Stone: Stone is another great material for concave engraving. Engravings are often done in: marble, granite, sandstone, and limestone. A hammer and chisel or pneumatic hammer is typically needed to engrave patterns or designs into the stone.

What Are the Examples of Concave Engraving?

Concave engraving is a type of engraving where the design is cut into the workpiece’s surface in a sunken or recessed manner. Some examples of concave engraving are:

• Signet Rings: For centuries, signet rings were used to seal documents. The design is, of course, engraved in a concave manner into the ring's surface. A signet was traditionally a symbol of a king's authority. Where we might today leave a signature to seal a deal, a nobleman in days past would transfer the design of his ring into a wax or clay seal by pressing the ring’s face into it. This results in a design that is raised, leaving a unique signature on the seal. Figure 1 is an example of a signet ring:

• Jewelry: Pieces of jewelry are sometimes engraved with concave designs. This is done to add dimension and texture to jewelry pieces such as bracelets, earrings, and pendants. 

What Are the Industries That Use the Concave Engraving Method?

Concave engraving as a technique is used in many industries including: watchmaking, printing, jewelry, and firearms. Jewelry shops are among the most common users that explore this style of engraving. It is a great technique for creating detailed textured surfaces — even on tiny pieces — that enhance the items’ value and appearance. 

Another common use of concave engraving is in the printing industry. They use it to incise an image or a design into a printing device. Following that, ink can be poured onto the incised line or depressed area. Paper or other material is then pressed against this surface to accept the printed text or image. The technical term for this is “intaglio printing.” 

The benefits of concave engraving also find relevance in the production of firearms. It is used to create intricate designs on gun barrels, receivers, and other parts. 

How to Use Concave Engraving?

There are various ways to employ concave engraving. We will look at the steps involved when a laser engraver is used: 

1. Use a CAM software program to create the design. Slicer software is then needed to translate the design to a form that the laser machine can interpret. 
2. Secure the material onto the laser engraving bed. Use clamps or double-sided tape to keep the material in a fixed position.
3. Set all the parameters that govern the laser machine’s operation. These settings include the speed and power of the laser. Laser engraving generally requires an operating power of less than 60 W. You’ll have to adjust settings to meet your desired cut depth and the material’s hardness. It is best to check the laser’s OEM manual for the recommended settings.
4. Take necessary precautions; make sure you have proper ventilation and personal protective equipment (PPE).
5. Engrave the design on the material.

Is Concave Engraving a Type of Laser Cutting?

No, concave engraving is not a type of laser cutting. The two processes operate on the same principle, but they get applied differently. For instance, when a material is being laser engraved, the laser is instructed to only vaporize enough material to reach the design’s intended depth. It should not cut through the material entirely. The result of this process is visually appealing and typically adds to the item’s value. Every laser engraving takes one of three forms: concave, convex, or ablation engraving. The method will determine how the workpiece gets carved or engraved. By contrast, if you laser-cut a workpiece, the laser will slice all the way through it. 

Is Concave Engraving Suitable for Deep Laser Engraving?

Yes, concave engraving is suitable for deep laser engraving. The design and setup process is no different, but it does require a laser engraver with enough power. Essentially, the power of a laser engraver is what determines how much material can be removed from a workpiece. The greater the power, the easier it is to engrave or remove material from the workpiece.

Summary

This article presented concave engraving, explained what it is, and discussed this method in detail. To learn more about concave engraving, contact a Xometry representative.

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