Applying finishes to hardwood floors is one of the more tricky aspects to installing floors. If the sanding or screening process is done improperly, dreaded swirl marks will appear on the floor.
Unfortunately, swirl marks tend not to show up until finish or stain is applied. This means that the contractor must completely re-do all their hard work, leading to to lost time and money.
In this post, we will discuss what can be done to prevent swirl marks from happening in the first place.
#1: Be diligent
Know what the appropriate sanding pad or screen is for each situation you encounter. Most manufacturers have general specifications for how long you should use their abrasives, and how to use them. For silicon carbide abrasives (black paper), the common rule is 500 SQ FT per screen.
Other types of abrasive will have different general specifications. Make sure to follow the proper grit sequence (click here for our guide to choosing the right grit sequence), and be sure to stick with sandpapers that have similar sharpness for the entire job or project.
#2: Clock the buffer
If you imagine the part of the buffer where the handle meets the base as 6 o’clock, then directly opposite of that will be 12 o’clock.
Buffers do the majority of their cutting from the 12 o’clock area to 3 o’clock area. Keep this in mind as you buff the floor so you don’t create too much of a scratch pattern on one side.
Make sure you are running the buffer parallel to the grain, not across the grain.
It is also important to overlap your passes with the buffer. You should be placing the buffer anywhere from 3” to 8” over the previous path.
#3: Remember, “slow and steady wins the race”
Going too fast will not benefit the quality of your sanding and screening. It is far better to walk and a slower, more deliberate pace.
It is also important that your buffer is steady and balanced. Make sure you have a quality drive block and drive pad. If your drive pad is old and worn it is probably not balanced correctly any more. Spending the money for new and fresh equipment is less costly than spending the money to completely re-do all your work.
A good way to make sure your equipment is performing properly is to have it tuned up every few months, which our machine repair shop can do for you.
#4: Pop the grain
Popping the grain (also known as water popping) will help to expand the fibers of the wood in fine scratches and help reduce the potential of swirl marks when you apply stain and finish. Popping the grain is appropriate for extremely soft woods like white pine.
For more information on properly popping the grain of a wood floor, check out this guide by Wagner Meters.
Leaving grit, particles, and dust from previous cuts is just asking for trouble. When you are screening, we implore you to attach a vacuum to your buffer. Vacuuming will significantly reduce the chances of dirt or debris from getting under the buffer and causing irregular depth of cut.
Even if your buffer or sander comes with a vacuum system attached, we highly recommend going over the floor with the ProTeam MegaVac in between grits and coats of finish.
#6: Opt for Norton Red Heat Screens and Sand Dollars
Norton Red Heat screens are great for very dense woods like ipe, cumaru, Brazillian cherry, maple, and hickory. These screens cut longer on harder substrates. Click here to purchase Norton Red Heat screens.
Red Heat screens are also appropriate for all species with aluminum oxide prefinished floors. Aluminum oxide is an extremely hard mineral. However, the alumina ceramic that the Red Heat screens are made of are even harder than the Aluminum Oxide.
Norton Sand Dollars are another solution. These sanding pads offer a unique design allowing for abraded material and debris to be collected in a cut slot. This keeps the material from clogging the pad and creating a spot for potential unwanted scratch. They are available in multiple grit progressions providing for uses ranging from bare wood preparations to between coats on oil or waterbase.
If you use Norton Red Heat screens or sand dollars, you’ll be in pretty good shape as far as preventing swirl marks in your hardwood floors.
#7: Stray away from damaged screens and paper
This might seem like a no-brainer, but it’s important to remember. Make sure you check the quality of all your screens and paper before using them. Any damage to the abrasives dramatically increases the risk for swirl marks. Hitting baseboards, shoe or quarter round, and even vent holes can cause damage to the screen, resulting in potential swirl marks.
If you have any additional questions or concerns, feel free to contact us at (800) 737-1786 or firstname.lastname@example.org.