Wax resist burnout is an image transfer technique where unfired clay painted is etched directly with a CO2 laser.
1. A layer of wax resist is applied to unfired clay
2. A CO2 laser etches an image onto the clay, burning through the wax resist
3. Underglaze is painted on the exposed clay
4. Excess underglaze is wiped off
Workflow
A high-contrast image is “image-traced” in Adobe Illustrator to retrieve an etch pattern.
A wooden spoil board is used to position the unfired clay piece and absorb and excess zaps from the laser. I like to etch a rectangle or circle to let myself know the perimeter of my working area, this way if my etch design is center to the rectangle, it is center irl.
Laser settings
A a 90W laser I’ve achieved good results with the above settings ^
500mm/s
16% power
604 Lines Per Inch
Speed: Controls the speed at which the laser head moves left/right - the slower the speed the more energy/heat is input
Power: Power
Lines per inch: Controls the density of lines in which the laser strikes, this affects the resolution of the image, it is aka “dots per inch”
Settings will have to be fined tuned for each machine. The goal is to achieve clean wax burnout- not firing or sintering the clay beneath the wax. I’ve achieved best results by running the laser at a high speed, and dialing the power up until the wax layer is breached.
Troubleshooting
I have found this technique to be mostly straightforward. The only error I’ve encountered is the wax gumming up and not fully breaching to reveal clay underneath. This is caused by the laser being out of focus. Playing around with the laser focus resolves this issue.
The other issue is running the laser too hot, this can effectively “fire” the clay beneath the wax, making it less absorbent of the underglaze. Dial down the power.