When renovating an old house with deeply scratched or pitted flooring, sanding may be your only option. However, if the floor is in good condition and needs only refinishing, sandblasting is the best solution. Sandblasting will quickly remove embedded stains, grime and old varnish without damaging the original flooring. The downside is that you also will have to varnish your skirting boards and nearby trim. In addition, no matter how careful you are, the adjacent rooms will need to be thoroughly dusted and vacuumed.
Clear the room. Mark the adjacent flooring by masking off the entrances with plastic sheeting and masking tape.
Ventilate the room by opening the windows and placing inward-blowing electric fans at the entrances.
Fill the sandblaster hopper with silica sand. Shut of the aggregate feed valve. Start the compressor and set the pressure regulator to 50 PSI (lbs per square inch).
Start at the farthest corner. Open the sandblasting aggregate feed valve. Point the nozzle away from your body and hold it 10 to 14 inches above the floor. Press the trigger and move the nozzle over the floor with two sweeping passes.
Release the trigger and inspect the floor. If every trace of varnish has been stripped away, move on to the next section parallel to the wall. If not, do another pass. If the floor is clear, turn the pressure up to 80 PSI before the next pass.
Inspect the second pass. Adjust the pressure if necessary until all varnish is removed with two sweeps of the nozzle.
Sandblast the rest of the floor by working toward the entrance. Sandblast slightly overlapping passes with a continually sweeping action. Use short bursts to remove any thick, stubborn layers of varnish you encounter, but keep the nozzle moving when doing so. Sandblast the rest of the floor.
Sweep the floor with a broom and inspect the surface carefully against the light. If any shiny or varnish discoloured areas show up, mark them with a ring of chalk. Clean up any missed areas with brief burst of sand.
Keep the nozzle moving at all times.
While sandblasting: Wear a full Tyvek painter's suit with a hood. Secure the cuffs with rubber bands. Tyvek is a breathable fabric, so you won't get hot and sweaty while working. Protect your eyes with safety goggles. Wear a good quality respirator. Wear welder's gloves and old sneakers.