I have a medium sized patio with steps going down into the garden (approx: 40 sq mtrs). After jet washing, I used a long pile roller to apply the sealant generously to the sandstone. It was quick and easy to apply the two coats recommended and still had 2.5ltrs left over from the 10ltrs purchased. 4 weeks on and my patio and steps still look great. The colours in the sandstone really stand out even when its dry. There's been no rain since treating, so I haven't had a chance to see how whether it reduces algae and fungi growing. Highly recommended this product.