DO-IT-YOURSELF : To Preserve Look, Use Same Finish on Floors

While most new and not-too-old wood floors are being finished or refinished with polyurethane, when it comes to the older floors, sticking with the original varnish or shellac can be a good way to achieve an authentic, period look.

Many times, if a floor has been properly maintained, it’s possible to coat over the existing surface with the same finish. First prep a small test area by hand-sanding it, then add the chosen finish. If it bites and has the right look, it’s probably the same finish that’s on there.

Dissimilar products won’t work on each other, so don’t be tempted to shellac a varnished floor--it simply won’t hold. (A note of caution if you go with shellac: This historical finish won’t tolerate alcohol or water spills, so be sure to consider the room’s usage beforehand.)

You can add a coat of wax over either, if you choose, to preserve and protect the finish while adding a bit of luster to the floor. Keep the surface free of dust and dirt with regular dust mopping. Expect to re-wax periodically as the protective coating wears away. It’s a small price to pay for retaining a piece of history.

If a previous owner refinished your old house floor with a coat of polyurethane, you may decide to strip it off and bring the floor back in a more authentic manner. Although this newer finish is extremely durable and offers a longevity most historical finishes don’t, many restorers find it looks plastic and doesn’t mesh well in restored homes.

If the floor is badly stained and scratched, the floor’s thickness is the indicator you should use to decide whether sanding is feasible.

Extreme care should be taken when working on old parquet floors. Since these boards are only generally about three-eighths of an inch thick, there is probably only about one-eighth of an inch to work with until the tongue is reached. As a result, many restorers will recommend stripping the floor by hand, either with a hand scraper or chemicals if the finish must be removed.

Although this obviously can be a very labor-intensive job, it may be the only way to refinish some old parquet without ruining the floor. Since an old strip floor is thicker, many of these floors can be sanded.

There is another factor that should be taken into consideration when you’re deciding whether to sand an early floor. Remember that flooring spans structural members. And the construction techniques common to many old homes are different from those we consider standard today. More than likely your floor joints are about one inch thick, the thickness of the board is adequate for this large span. But when the board is worn (or sanded) down to 7/8 of an inch or 3/4 of an inch, you’re apt to get some spring in the floor.

It’s interesting to note that every sanding decreases the thickness of a wood floor by about 1/16 inch to 3/16 inch. So there are only so many times you can sand down a wood floor. An easy way to gauge the thickness of the old floor is to remove the molding and baseboard or a floor heating register to reveal the edge of the wood.