Products to Remove the Original Finish
A chemical stripping agent can be used to remove the varnish or polyurethane coating over the floor. Results are mixed, however, when it comes to using this type of product to remove the actual stain on the wood. Typically, the stain penetrates too deeply into the wood for a chemical to remove it. Heat guns are a non-chemical option that can be used to melt off the original coating of varnish. They must be used with care to avoid burning the floor.
Choosing a Darker Stain
No-sanding techniques typically do not remove the original stain on the floor. If you want to make your floors lighter than they are right now, sanding is the best option. However, if you plan to make your floors darker, a no-sanding approach will work. Keep in mind that with this method, the finished color of the wood might be slightly different than shown on the package. One coat of stain is recommended for this method, as more than one coat will require additional sanding.
No-Sand Polyurethane Products
Once the floor is stained, it will need to be protected with polyurethane. Typically, this meant sanding the floor before applying the poly coat and then again before putting down a second or third coat. Newer polyurethane products offer the ability to go with a no-sand method, as long you add the additional coats within 12 hours of the first application of the poly coat. Look for this attribute on the label of the polyurethane can, as not all brands are alike.
When Sanding Can't Be Avoided
If the wood floors are water damaged or show excess signs of wear, sanding may be the only option that will work. Changing the floor color dramatically will also typically require sanding. Sanding is also necessary if another flooring was glued on top of the floor boards. The adhesive used for carpeting or vinyl flooring typically penetrates into the wood, changing the color. In addition, glue-on flooring materials usually require some surface scoring of the wood, which damages it slightly. Sanding is the only way to restore the wood in this instance.