If the polyurethane finish on your wood floor is dull and in need of repair, then you should act quickly. The longer you wait, the more the poly finish will wear away. This is problematic because it can cause the floorboards to age prematurely. The stain on the wood might wear off in sections if it's exposed. If this happens, then you will have to strip the entire floor and stain it afresh. Rather then let it get to this point, take the opportunity to scratch and recoat with new polyurethane. Below is a step-by-step guide that will tell you exactly how to do this and what you need.

What You Need:

Floor Buffer With Pads- You can rent this for the day. The maroon pad that comes with the buffer will be used to scratch the topcoat of the poly and make it ready to receive a new coat.

Lambswool Roller- Buy this at a home improvement store. This is used to apply the poly. It is superior to a paintbrush because it won't leave streak marks.

Mineral Spirits- Used for cleaning up dust. You will wet a rag with mineral spirits after sanding the topcoat. The damp rag will pick up dust easier than a dry rag. The mineral spirits are better than using water because the spirits evaporate quickly and won't leave the floor damp.

Fine grit sandpaper (160-120)- To hand sand the spots where the buffing machine can't reach.

New Can Of Poly- Avoid the need to thin out old, thick poly with mineral spirits.

Water Based Poly- Water based polyurethane allows you to apply multiple coats in one day. There is no heavy smell that requires you to wear masks and set up excessive ventilation.

Oil Based Poly- Less expensive than water based. It creates a beautiful golden glow that water based poly won't lend to the wood. Water based poly goes on clear. For pale woods like oak or pine, oil poly is superior for bringing out the color. Dark woods such as cherry, maple, or chestnut will look ok with water-based poly.

The Step-By-Step Guide

Scratch The Top Coat Of Poly 

In order to apply new polyurethane you need to "scratch" the old one. This removes the top layer without removing the lower layer of wood stain. Place the maroon pad on the buffer and buff the floor in an even motion. You should see a fine dust appear on the floor. This is the sanded off polyurethane.

Hand Sand The Corners Of The Room

You will need to get down and hand sand the corners of the room because most floor buffers won't be able to get close to the edges. Make sure that you are using the fine grit sandpaper.

Remove The Dust

Sweep the dust out with a broom. In order to get the fine particles of dust off the floor, dampen a rag in the mineral spirits and wipe the floor. Make sure to keep the rag damp during the entire process. You don't have to dry the floor because the mineral spirits will evaporate.

Apply The Poly

When the floor is dry, it is time to apply the polyurethane. Use the lambswoll roller and make even passes on the floor in the direction of the grain. Do not pause during the process because the polyurethane can pool up in spots and dry too thick. This will cause bubbles and eventually cracks. So make sure it goes on evenly.

If you feel you cannot do this on your own, talk with a professional floor refinishing company, such as Cooper Floors.