Refinishing Hardwood Floors: What Pros Won’t Tell You (Part 2: Sanding)

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The “Pro” Blogs Make It Look Easy (If You Have Picture Perfect Floors)

Refinishing hardwood floors: you just rent a few sanders right?  How hard can it beLike many others, you own or bought a house, and a rewarding but challenging decision awaits you with unlocking the potential (and future monetary value) of hardwood flooring.  In this Post, I will specifically be discussing Sanding.  For the Introductory Posting, please see Part 1.   


Before you go through the time and expense of attempting to refinish a hardwood floor, you may want to consider what type of “look” you are going for. What’s the difference?

After learning from a friend who did both original hardwood floors and had modern hardwood floors installed, the difference really boils down to the look (both are beautiful when done correctly).  Compare the two photos below:  1. is original refinished 1930’s yellow pine, and 2.) “modern” installed hardwood floors (and there are many derivatives of engineered vs non-engineered, and various price points, etc.)

Circa 1930’s Yellow Pine (Note: Fully Finished)
Modern Wood Laminate Flooring


Set aside the fact that one image isn’t a picture perfect stock photo, the point is that that original hardwood floors give off a certain look and feel of being much more “historic” (for lack of a better word).  Wood ultimately comes in all shapes, sizes, colors, and there is no shortage of examples online.  The real point being, that an older original floor will likely show flaws, dings, dents, etc., that can potentially cause you a number of headaches.  However, if you like that “non perfect” look, that is where you will likely end up.  Some people call this “character”.  However, don’t confuse total dog shit with “character”.  I have seen people try to pass off poor workmanship etc., as “character”.  There is a big difference!  

Imagine a 1960’s Fender Stratocaster guitar versus one from 2023.  Both look similar, but the rarity and age of the 1960’s can never be re-duplicated.   There are only so many forests in the world (going backwards in time).  



So you’ve pulled up some carpet, ripped out tile, and discovered that you have acceptable original hardwood flooring.  You’ve read a few Blogs and Step-by-Step Instructions and made your checklist of materials.  Great!  Now comes the hard part: all wood has variables. 

Assuming that you have removed all of the staples and nails, and removed everything from the rooms,  you’ve gone to a big-box hardware store to rent (at least) your Drum Sander, and your Edging Sander (heavy aren’t they!)  Don’t forget to also buy an ample supply of 36, 60/80, and 100/120 Grit Drum Paper, as well as a very ample supply of Edging Sander Discs.  (Tip: return anything you don’t use). 

Remember also to set aside at least 3 days worth of time to complete the work- and the time is ticking on those Rentals!  (More days= more $$$).  

Let’s take a look at some examples of “non perfect” original hardwood floors, after a pass or two with the Drum Sander (on 36 and 60, working of course, with the grain):

Note: the “zebra”-like striping

After multiple passes at this, you may be scratching your head wondering why you have streaky floors, still with varnish and the old floor color? 

This is due to varying levels and inconsistencies with the wood, as well as “cupping”.  Cupping is a moisture imbalance in the wood that may be caused by decades of varying weather conditions and/or moisture in the home.  Using a disc or orbital sander on cupped floors will inevitably create swirl marks and circular patterns on your floors, even when done carefully or with fast movements.  Similarly, sanding something like that by hand or with a palm sander with large rooms would wear your patience to the bone.  

What is the solution?  Working diagonally “against” the grain.  Note, that the word “against” is in quotation marks.  You are not really sanding “against” the grain, it is just a sort of half-counter measure.  For this, I would recommend using a 60 or 80 Grit, to be on the safe side and test the result.  For particularly difficult rooms, you might lower back to the 36 Heavier Grit.  

An excellent and more professional and scientific explanation can be found watching this “epic” Australian guy here.

Note: the diagonal sand lines now in the floor (not the arrows, lol)

BUT: a very important point to note, is that once you go diagonal, you then need to re-sand your floors straight with the grain.  If you continue onwards to sanding and varnishing, you will have diagonal lines in your floors!  

This means that you have now Drum Sanded your floors upwards of potentially 5 passes.  (2 regular, 1-2 diagonal, and 1 more time to take out the diagonals).   

(Not exactly how they show you in the picture-perfect videos and blogs…)


Edging Sanders are very heavy and cumbersome, but with a little bit of practice, you will begin to find a rhythm to it.  Edging (like the name implies) will allow you to get as close to the walls as possible, but you want to avoid creating a major level change, even with the later addition of baseboards.  

While trim is a “final touch”, it is not a means to cover up everything, and having a level-changing “squiggly”  line below your walls can ruin the linear-ness (visual lines) of the room.  You may have to add additional quarter-round trim, and even then, level changes can be seen in the trim.  

Watch especially not to Edge a deep circle into the corners of the rooms.  The corners can be a delicate procedure, and must be hand-scraped using a wood scraper or cabinet scrapers, and the like.  Making a deep circle into your corners with an Edging sander will make a higher level change, causing you more work to level it down.   

A typical Edging Sander (aka pure evil).
Scraping corners by hand.


You’ve done the work of Drum Sanding and Edging but trickier yet, some of the “cupping” diagonal areas will be harder to “set back to straight” due to the same sorts of wood inconsistencies.  This is where you have one of two options:

1.) Go back to the big-box store and rent a Random Orbital Sander (for possibly now your final pass using a lighter 120 grit paper)

2.) Get down on your hands and knees and use a palm and/or belt sander to touch-up inconsistent areas.  Do this without grinding into the floors.  Vacuum, and look really fucking hard at everything 

In the case of the 1930’s original floors, I ended up having to do both of these!  The Random Orbital was OK, (work fast and without stopping), but then left some light swirl marks in the high/low areas.  You then have both the swirls and the diagonals to contend with!  

A Random Orbital Sander

 Be prepared to “finish” the sanding with an orbital and/or palm sander, to smooth out the remaining inconsistencies (and chances are you will lose your mind before getting all of them, and the lighting needs to be tip-top!)  

I was fortunate enough to have my old folks make runs back to the hardware store for me to buy additional sand paper for various machines.  Again, plan wisely.


Should you have spent the time and labor to sand the floors adequately, you should have an extremely “bare” appearance, void of any varnish and coloration.  Don’t confuse wood grain with coloration and try to sand your way to China.  Obviously, grains have some color, as you should NOT try to sand those away, and NOT OVERSAND the floors.  Know when to stop and enough is enough.   ALSO- BE EXTREMELY CAREFUL with your bare floors, as anything can now scratch or discolor them, including things like Shop-Vac wheels, dirt/oil on your shoes, etc.

The appearance should look something akin to this: 

 Be prepared for the “imperfect” and accept rolling with the punches in terms of getting creative with sanding, while not over-sanding!   

Chances are the floors will still not be “perfect”- remember, they may be a 100+ years old and were cut and installed by workers with far less advanced technology (or was simple more advanced…?)  

Part 3 of this Blog series is coming soon, discussing the floor staining and polyurethane (clear) coating.  

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