When engraving slate coasters with a laser, it’s crucial to find the right settings to achieve a clear and precise design. Generally, the recommended settings can vary depending on the specific laser engraver you are using, but here are some common guidelines:

• Power: Set the laser power between 30% to 50%. Higher power levels may lead to excessive burning or deeper etching.
• Speed: A slower speed of around 100 to 200 mm/s is typically effective. This allows the laser to engrave deeply enough without going too fast and missing details.
• Frequency: For CO2 lasers, a frequency between 300 to 500 Hz is recommended to balance the engraving quality and speed.
• Passes: One to two passes usually suffice. If the engraving appears too light, consider making a second pass, but watch for overburning.
• Focus: Ensure the laser is finely focused on the surface of the slate to achieve clean lines and details.

Before starting on your final project, it’s advisable to conduct test engravings on a scrap piece of slate to refine these settings further and ensure desired results.