Refinishing Aluminum Oxide Floors

I love woodworking to the core. Unfortunately, there are two aspects of the job I absolutely dread. One is staining, and the other one is refinishing aluminum oxide finished floors. The first time I ran my belt sander on prefinished floors was a nightmare. My usual 50 grit belt didn’t even scratch the surface before losing any cutting capabilities. I tried a rougher grit with absolutely no luck. Then I tried an 80-grit belt which seemed to work, but only for a few more square feet before giving up on me. I didn’t know what to do except keep changing sandpaper and pushing through it. Much like a long workout, I just had to put my head down and do the work. We call it “embrace the suck.” After using an endless number of belts and edger discs, I managed to strip the finish off and continue with my usual sanding process.

There were not that many floors like that in need of a refinish back in the early 2000s. I would maybe get one job a year that called for that type of sanding. Now, in 2025, the demand is growing, and those new floors that were put in decades ago need a full refinish. For the last 25 years I’ve been mainly sanding top nail floors, because that is the majority of the floors we have in the San Francisco Bay Area. Every now and then I would have the luxury of refinishing a tongue and groove floor. I call it a luxury because sanding a top nail floor is a lot more challenging to do. It’s like giving a contractor who is only used to sanding oak floors, a maple floor. You can get away with a lot of things on an oak floor that would get you in trouble on a maple one. Sanding floors had become second nature for me. I enjoy working with wood, sanding, installing, and creating. However, the aluminum oxide makes the fun part of working with wood not so fun.

Over the years, manufacturers have come up with different minerals and products to tackle these hard surface finishes. Each type of abrasive has its pros and cons. Those materials can vary from silicon carbide, garnet and ceramic to zirconia and aluminum oxide. Ceramic abrasives are harder minerals and area common material used to cut through those finishes. Know your stuff inside out, and it’ll make life easier.

Up until last year, I refused to touch any of these prefinished floors anymore. That changed for me after a friend called.

I completed the NWFA schools back in the early 2000s, and have taught many of them through the years. Why am I telling you this? So that you understand how being involved can make your life easier. For example, one day in 2024 I received a text message from another flooring contractor here in the Bay Area. He sent me a link to a new product for my planetary sander  It was a product designed for sanding aluminum oxide floors. Within one minute of looking it up, I knew it was the perfect tool for these floors. I messaged my contact for info about the tool. Something you can’t really get from just watching a marketing video. (The only reason I had his phone number, and the only reason he picked up the phone was because of our NWFA history together. This is a side note on why you should be around more flooring people and get yourself involved in the industry.)

You must know your finishes to understand what approach would work to sand them. I remember seeing a guy running his belt sander on a waxed floor very slowly because the wax wasn’t coming off. He thought maybe he was going too fast. The problem was he was building up heat by moving slower and making his sanding impossible. He should have moved the machine much quicker to avoid building up heat, essentially making more light faster passes than slower and fewer.

Same goes for hard finishes like aluminum oxide. The material on the sanding machine needs to be hard enough to stay sharp and at the same time not overheat. The set I purchased for my planetary sander has diamond heads. That allows for efficient sanding of these hard finishes.

They are easy to use also. After you inspect and vacuum the floor, install the plates onto the machine. Set it on the floor and start sanding in any direction you’d like. The direction of sanding is meaningless at this point. You are merely just removing 80-90 percent of the finish. Since there is much more sanding to do, just enjoy the fact that the finish is coming off easily. The idea is to move the machine fast enough to remove the finish without causing excessive heat. When you lower the moving plates on the floor, it feels like you are sanding with big rocks on the wood. The sound is different than running a belt or a disc. I recommend working the sander in about 200-300 square feet sections and check the plates for heat. My edger has the same diamond attachment though the attachment is a lot more aggressive. With this tool, you must move fast and let it almost glide on the floor with minimum pressure. It took me about 10 minutes to strip around 80 lineal feet of wall edge. That’s unheard of with any conventional sandpaper. It took me about 10 minutes to strip 100 square feet of flooring. I must add, this was  with zero effort. No need to walk back and forth with the belt sander, and no need to change belts every few minutes. Even though the tools were doing the hard work, they did it so smoothly and effortlessly.

This job had solid ¾’ red oak floor with a deep bevel. I had to strip the finish and then switch to my belt sander and edger to remove the bevel throughout the floor. I’d like to emphasize the importance of vacuuming the floor regularly and frequently. Any aluminum oxide particles left on the surface will quickly dull your sandpaper.

Basically, after you are done removing the finish it is a normal sanding job. Move up in grits and follow NWFA guidelines for proper sanding and finishing techniques.

 

Avi Hadad is the owner of Avi’s Hardwood Floors Inc. in San Pablo, California. He can be reached at avi@avisfloors.com.