Sandstone is porous, so being exposed to moisture and dirt for a long time can cause mould, fungi and algae to grow.

Here are some ways to remove mould from sandstone pavers, thanks to Marble Mosaics:

1. Chlorine bleach

  • Mix 1 cup of bleach and 1 gallon of water together and put it into a spray bottle.
  • Spray the mould, leaving it for 10-15 minutes, and then spray the area again.
  • Remove the mould with a scrub brush and wash it off with water.

2. Anti-microbial spray

  • Spray a substantial amount on the mould. While it’s drying, an airtight coating will form around the mould, choking its growth.
  • Rub off the mould with an old rag soaked in the spray.
  • Use a fogger rather than a spray bottle for big areas or those that are difficult to reach.

3. Paper and hot water

  • Shred white paper and place in hot water until soft.
  • Crush the paper to a pulp and spread it over the mould.
  • Wait for the stone to absorb the pulp’s moisture and loosen the mould. When the paper dries, it will drain off moisture from the sandstone and absorb the mould.
  • Remove the paper once the sandstone is free of mould.

When removing mould and using chemicals, wear rubber gloves, goggles and mask. The sandstone should also be dampened prior to cleaning. This will help prevent mould spores from spreading through the air.

Finally, applying sealant to the stone can stop moisture from being soaked into the stone and causing mould. Some sealants provide mould barriers.