Fireclay is a unique material used to make sinks and tubs. It maintains the appearance of porcelain or ceramic, but because the clay is so heat- and fire-resistant (it is created at a much higher temperature), the material's resilience is increased. Fireclay rarely suffers from chips or scratches, but when it does you can acquire a repair kit from your sink's manufacturer to reinforce the damaged area with similar damage-resistant material.
Clean the damaged area with a rag dampened in warm water and an all-purpose sink cleaner. Mildly abrasive cleaners are fine for removing any stains in the damaged area. If necessary, use a solvent cleaner, such as white spirit, to remove grease or wax.
Dry off the area thoroughly with a lint-free cloth. Shake your fireclay repair compound that comes with your repair kit for two full minutes to ensure that it is ready for use.
Apply the compound to the damaged area with the provided applicator. If the kit does not come with an applicator, use a toothpick or cotton swab to spread the repair compound. Make multiple passes, applying thin layers of compound until the damaged area is completely covered.
Protect the repaired area from moisture and pressure for at last 24 hours so that the compound can dry fully.
If you use a repair kit made for porcelain or ceramic, you may not achieve the same resilient finish or colour matching for your sink repair. If at all possible, obtain a repair kit designed specifically for your sink from your product's manufacturer.