laser Sealing Slate

Some say that a clear coat spray, such as gloss or matte spray paint, can make laser engravings on slate stand out and add contrast. Others recommend pre-coating with varnish or shellac to enhance the contrast. Some sprays that have been used for laser engraving slate include:

• Water-based Minwax Polycrylic: A Reddit user says this seals well and dries quickly
• Rust-oleum Lacquer: A Glowforge user says this dries almost instantly and can be washed off with water and dish soap after engraving
• Spray shellac: A Glowforge user says this is food safe 

Some other tips for laser engraving slate include: Cleaning the slate before engraving, Using matte varnish, and Testing to find the right settings for the slate. 

While some crafters seal engraved slate to increase contrast and durability, others say that sealing isn't necessary because the engraving is done into the slate rock