The Truth About Hand Scraping Wood Floors

The art of hand-scraping has been around for a long, long time, dating back to at least Thirteenth Century China. Do you recall the scenes in the movie "The Karate Kid" and the phrase, "wax on, wax off"? Technique was and is everything. Over the years, particularly with the advent of the industrial age, this art form has somehow lost its edge due in large part to a world of mechanization and quick turnaround.

Hand-scraping was a learned craft back then and it required lots of muscle and elbow grease and determination tempered with patience. The people who did hand scraping were true artisans. They were knowledgeable about the product. They also didn't have some of the chemicals to deal with that we do today. And therein lies a stumbling block to hand scraping old floors tempered by more modern technologies.

Just recently I stumbled across an old schoolhouse where some well-intentioned individuals were trying to restore the old wood floors. The first thing they tried was using a conventional rental sander. This wasn't very successful because the floors had layers and layers of old varnish and/or shellac.

The Nature of Durable Old Finishes

The problem with these old finishes is that they were very durable but had a low melting point. These properties cause two problems when trying to sand them with conventional rental sanders.

1. If you try to sand them with an orbital sander sometimes called a square buffer the durability is a problem. Orbital sanders are great for the final sanding after all the finish is off but are terrible at removing finish, especially old finishes. The reason is that they are not very aggressive.

2. The sanding surface of an orbital sander is twelve (12) inches by eighteen (18) inches or two hundred sixteen (216) square inches. If the machine weighs one hundred and thirty pounds there is less than a pound per square inch touching the floor. This isn't really very much when you are trying to remove finish that is built up on a floor. Many people use a square buffer thinking that it is safe and won't cause the drum marks of a drum sander.

Many rental stores even appeal to this fear of using a drum sander and end up recommending the square buffer. When I was working at Home Depot in Denver which had a tool rental store, time and time again I would see people returning a square buffer totally frustrated. After spending several days trying to remove finish and going through lots of sandpaper they were totally aggravated . The truth is a square buffer is not designed to remove finish.

After the folks at the school found out that the square buffer wasn't effective they got the idea to chemically strip the floor. This is an even worse idea. The problems with chemically stripping a wood floor are many.

1. As soon as you add chemical stripper to old varnish you are making hazardous waste. After making seven five-gallon buckets worth of hazardous goop and hours and hours of hand scraping this goop off the floor they abandoned the idea of chemically stripping the floor.

2. When you chemically strip an old wood floor some of the stripper ends up in the cracks between the boards where it doesn't get totally removed. When you get to putting finish on the floor the solvents in the finish reactivate the stripper causing all kinds of problems with the finish drying and hardening properly.

3. Hand scraping a wood floor that has chemical stripper on it is very messy and hard work. Everything gets sticky and gooey.

4. Many strippers can burn your skin and are not very pleasant smelling either.

5. Chemical strippers tend to lower the melting point of the finish even below what it was before, so sanding it is going to fill up a lot of sandpaper.

6. Hand scraping a wood floor takes a long time and is very hard on the body.

So the next thing they tried after three weeks working on one room was to rent a drum sander and edger and sand the floor. This is where the melting point comes into play.

A Quick Primer on Sandpaper

Let me explain a little about sandpaper so you understand why this is a factor. One hundred (100) grit sandpaper has 100 grains of sand per square inch. This means that there are 100 points of contact with the wood floor per square inch. This creates a certain amount of friction which results in heat. When the temperature reaches the melting point of the finish it will melt and fill up the sandpaper.

Thirty-six (36) grit sandpaper has only 36 grains of sand per square inch which means there are only 36 points of contact with the floor. Less heat is created so it takes longer to reach the melting point of the finish.

In tough jobs like this schoolhouse floor I use 12-grit sandpaper just to get the finish off. Once I am to the wood I use progressively finer and finer sandpaper to remove the scratches the 12-grit sandpaper puts in the wood. Very often I have actually edged the whole floor with 12-grit paper to get to the wood. Once I have most of the finish out of the way my drum sander takes out the edger marks and finishes the floor.

Unfortunately, the coarsest sandpaper available for most rental machines is 24-grit sandpaper so the folks at the school went through a lot of time and sandpaper cleaning up this mess.

When It Comes To An Older Floor - Consult First

By the time I found out about this nightmare project the floor had been sanded to the point where most of the finish had been drum sanded off and was ready for 36-grit sanding followed by 60-grit sanding, and 100-grit sanding. I did the final sanding with a 150-grit screen on my square buffer.

If you have an old floor to restore I would avoid hand scraping and chemical stripping altogether and save yourself a lot of frustration. It is possibly a good idea to get some professionals in to look at the floor to get an estimate and ask some questions before you decide to tackle this yourself.