Sealing engraved slate coasters is essential to protect the design and ensure their durability. Several materials can be used for this purpose:

• Acrylic Sealers: Acrylic sealers offer a clear, protective coating that’s easy to apply and dries quickly. They provide a glossy finish while enhancing the color of the slate.
• Polyurethane: This type of sealer creates a robust protective layer, available in both water-based and oil-based formulas. Oil-based options tend to offer better durability, while water-based products dry faster and have fewer odors.
• Epoxy Resin: Epoxy resin provides a strong, waterproof seal, ideal for coasters exposed to moisture. It creates a thick, glossy finish that showcases the engraving well.
• Penetrating Sealers: These sealers penetrate the slate surface and repel moisture without altering its appearance significantly. They are excellent for maintaining the natural look of slate while providing protection.
• Spray Sealers: Easy to apply, spray sealers can coat the coasters uniformly. Look for products labeled as suitable for stone.

Always ensure that the chosen sealant is non-toxic and safe for surfaces that might contact food or beverages.