Engraving slate coasters with a laser requires precise settings to achieve quality results. Here are the recommended laser settings:

• Laser Type: CO2 lasers are most effective for engraving slate due to their ability to produce the necessary heat for etching the surface.
• Power Settings: Set the laser power between 20% to 40%. Lower power helps prevent burning through the slate while still allowing for effective engraving.
• Speed Settings: A speed setting between 100-300 mm/s is typically ideal. Slower speeds can enhance engraving depth, while faster speeds can yield a lighter etch.
• Frequency: Use a frequency setting of around 500 Hz. This helps to ensure a clean engraving without excessive charring.
• Passes: Depending on the desired depth, 1-2 passes are usually sufficient. Multiple passes may be necessary for deeper engravings.
• Focus: Ensure the laser is properly focused to achieve clean edges and crisp detail.

Always conduct a test run on a scrap piece of slate to fine-tune settings for optimal results based on the specific laser equipment used.