Sealing slate coasters can significantly affect the appearance and durability of engraved designs. When slate is sealed, a protective layer is formed over the surface, which can influence how the engraving is perceived. First, the sealant may alter the contrast between the engraved areas and the surrounding slate. Engravings on untreated slate often appear more pronounced due to the natural color variations in the stone, while a sealant can create a more uniform appearance that may lessen visibility.

Moreover, sealing can impact the texture of the coaster, softening the crispness of the engraved edges. Depending on the type of sealant used, it could fill in any fine lines or grooves from the engraving process, leading to a smoother finish that may detract from the detail of more intricate designs.

However, sealing slate coasters also has benefits, such as providing a protective layer that helps guard against moisture, stains, and wear. This enhances the longevity of the product, ensuring that the engraving remains intact and visible over time, even if the initial contrast is altered. Ultimately, the choice to seal or not should consider both aesthetic and functional factors.