Flagstone is a porous stone and is considered natural. Since it has pores, it can easily absorb moisture and is prone to scratches, cracks, chips, and other damage. This is why sealing flagstone becomes crucial. Using a seal, you can preserve the beauty of the stones, avoid damage, and maintain durability. A sealer fills up the spaces and the pores in the stone. This increases the strength and protects the stone from moisture, water, and any liquid. For a natural stone like this, an acrylic sealer is the best type. It maintains the natural beauty of the stone by giving a matte finish.