Question 1

How to seal coping stones

Clean the stone thoroughly and allow it to dry completely. Two or three consecutive dry days at minimum. Sealing damp stone traps moisture and prevents the sealer from bonding correctly.
Check the weather forecast. You need at least 24 hours of dry weather after application.
Apply the sealer with a brush, roller or low-pressure sprayer following the manufacturer&#8217;s instructions. Most impregnating sealers require only one coat on reconstituted stone and two coats on more porous natural stone.
Allow to cure fully before rain arrives. Most sealers are rain-resistant within two to four hours but take 24 hours to reach full effectiveness.

What sealer to use

Accepted Answer

For reconstituted stone: a silane or silicone-based water repellent. These are widely available from builder&#8217;s merchants and stone suppliers and are sold under various brand names. Look for a product described as breathable and impregnating.

Question 2

How often to reseal

Accepted Answer

Penetrating sealers on reconstituted stone typically last three to five years before reapplication is needed. On natural stone in high-exposure positions, two to three years is more realistic. The simplest test is to pour a small amount of water onto the surface. If it beads up and sits on the surface, the sealer is still active. If it soaks in immediately, the sealer has degraded and it is time to reapply.

Do Coping Stones Need Sealing? A UK Guide