How 3D Corten Steel Letters Are Made
When you see a 3D Corten steel letter, you might think it is simple work, but in this article, we are going to tell you about the careful work done behind every letter.
First, Let’s Talk About the Flat Metal Letter
It does not have any depth. A 3D letter is different. It has a front face, side return strips, and a rear mounting section, and each part fits together to create the final shape.
Choosing the Corten Steel
The first step is choosing the right steel. The fabrication process uses 2 mm and 3 mm Corten or weathering steel. Our company uses the best 3 mm Corten steel.
We do not use steel with a plain metal finish. The surface is prepared to develop a rusty golden patina. This gives the finished letters their warm and natural look.
The thickness depends upon the designated and required design.
Preparing the Letter Designs
The 2nd step of this procedure is, before any steel is cut, the letter design is prepared digitally.
The chosen font is vectorised so the exact shape can be used for cutting. For example, a font named Arial Black.
We use that font to convert the letter into vector form, then the outline is prepared for the cutting process. This stage is important because the digital shape becomes the physical shape of the finished letter.
Before fabrication, all the curves and openings are represented correctly.
Cutting the Face and Rear Mounting Plate
Now the design is ready, and the steel moves to the cutting stage.
The front face and back mounting plate are cut using a CNC fibre laser or plasma cutter.
The front face creates the visible part of the letter. The rear mounting plate is part of the structure used for installation.
Precision at this stage matters because if any part is not made correctly, a flat face alone does not create a 3D letter.
Adding the Side Returns
The next stage is adding the side returns.
It will not look like the original letter without adding the side returns. Narrow strips of Corten steel are cut to match the required depth of the letter.
The supplied fabrication process gives 25 mm to 50 mm as an example of the depth range.
These strips are then shaped around the outline of the letter. Curved sections may need to be bent or notched so the return follows the face properly.
3D Corten steel letter showing its side depth.
We did this so we can form a continuous 3D dimensional form around the letter
Tack Welding the Letter
Once the return strips are positioned, they are tack welded to hold everything in place.
The tack welds are made from the inside. They are placed every 3 to 4 inches to help keep the structure in position while reducing distortion.
You cannot see this stage on the visible product. It helps to keep the pieces together.
Completing the Welds
Welding is not the final step in fabrication.
Once we complete the structure, we check the exterior edges and clean them. The edges are ground using a flap disc.
This removes rough areas and helps leave a cleaner finished surface.
It is a simple step, but it changes the way the finished letter looks.
Preparing the Rear Installation Section
The finished letter also needs a way to be secured in place.
Our every COR10 3D number or letter comes with a rear square panel at the bottom. We added the pre-drilled holes for the installation, so you do not need to worry.
The rear section provides access to the fixing points.
How Our Company Installs the Letters
There are 2 methods for the installation.
For installation on a level, solid surface, we thread the pre-drilled holes in the supplied Dyna bolts. They are then screwed into the solid surface to secure the letter.
Now, there is also another option available. Liquid Nails can be applied to the bottom of the letter before it is attached to the solid surface.
We did suitable work on how the bolts should be attached according to the surface.
Pre-Weathering the Corten Steel
One of the most distinctive parts of our company’s process happens before delivery.
The numbers and letters are pre-weathered.
COR10 does not use chemical accelerants for this process. The company uses an organic seawater bath solution.
The process is intended to help create a protective weathered layer and encourage more even weathering after installation.
This means that you do not receive the letter in a completely untreated condition and then have to wait for the first stage of weathering to begin.
Full Process Explanation
The full process can be summed up in a simple sequence:
| Stage | What Happens |
|---|---|
| Material selection | Corten/weathering steel is selected |
| Digital layout | The chosen font is vectorised |
| Precision cutting | Face and rear mounting plate are cut |
| Return fabrication | 25–50 mm return strips are formed |
| Tack welding | Sections are secured from the inside |
| Full welding | Inner joints are fully welded |
| Finishing | Exterior edges are ground and cleaned |
| Rear preparation | Mounting panel and pre-drilled holes are prepared |
| Pre-weathering | Seawater and direct sunlight are used for about four weeks |
| Installation | Dynabolts or Liquid Nails can be used on a solid surface |
Why Every Stage Matters
You may think, why is every stage important? Why can we not skip any stage?
So here is the answer.
The front face gives the letter its visible shape. The return strips create the depth. Welding joins the structure, while grinding cleans the finished edges.
The weathering stage then gives the steel its characteristic appearance. Finally, the rear mounting section makes it possible to secure the finished letter in place.
Want the Finished COR10 3D Letters?
This fabrication process explains how the letters are made.
COR10’s 3D Corten steel letters are available in A–Z and are listed in several sizes and finishes.
You can see the finished product and available options here:
