Ronseal Diamond hard Medium oak Satin Floors Wood varnish, 2.5L. Spend less time varnishing your floors and more time enjoying it with this Perfect Finish Diamond Hard floor varnish. It comes with the Perfect Finish applicator which has a long handle, taking the backache out of varnishing your floor. The Perfect Finish pad applies the optimum amount of varnish, so you don’t get any brush marks, and is 5 times faster than using a brush. It’s also the toughest varnish Ronseal do, so it’ll last, keeping your wooden floors protected and looking great for longer.. This medium oak floor varnish from the Ronseal Diamond range can be applied to interior using a brush. The varnish dries in just 30 minutes and will cover up to 18 m² per litre on average. Floor varnish by Ronseal.