Common sanding FAQ.

Are you sure I can do this myself?

You can do this yourself if you take advantage of the free lesson that comes with every 24-hour (or longer) sander rental from Pete’s—just be sure to book the lesson in advance, because we only have one training floor.

If you can follow instructions (and if you stop consulting your handy ‘friends’ who think they know all about hardwood floors) and are motivated and reasonably fit, we are quite sure you can do this yourself.

We don’t promise that you will do the same job as a professional, but we can ensure that you don’t cause harm to your floor or yourself.

You don’t need to be big or burly to do a fine sanding job!

What does it cost? How much money will I save?

A good rule of thumb is that it doing it yourself should save you at least half the cost of hiring a reputable contractor to do it for you. In today’s market, DIY will run you about $2 per square foot. 

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This estimate includes machine rental charges, abrasive, contractor-grade finish, and assorted small tools. Hiring a professional will cost $4.00 – $5.00 per square foot.

So, if you are refinishing a typical 450sqft. living/dining area, you’ll typically save at least $1,000 if you do it yourself. Keep in mind though, that smaller areas tend to be slightly more expensive because the cost of the sander rental is not spread over as many square feet.

A single bedroom 10’x12′ can cost up to $300. But keep in mind that most contractors have a minimum job price, so a single bedroom will still cost $700-$800 to hire out, so there can still be a significant savings.

How long will it take?

Three sanding passes with both the drum sander and the edger in one room of 140sqft takes the average customer, working alone, five hours.

Allow extra time for houses that are more than 50 years old, for jobs that include multiple rooms (more rooms means more edging which takes more time) and for jobs involving heavy layers of old finishes.

Details

You can do this yourself if you take advantage of the free lesson that comes with every 24-hour (or longer) sander rental from Pete’s—just be sure to book the lesson in advance, because we only have one training floor.

If you can follow instructions (and if you stop consulting your handy ‘friends’ who think they know all about hardwood floors) and are motivated and reasonably fit, we are quite sure you can do this yourself.

We don’t promise that you will do the same job as a professional, but we can ensure that you don’t cause harm to your floor or yourself. You don’t need to be big or burly to do a fine sanding job!

What kind of sanders do you rent??

All of our rental drum sanders are Clarke EZ-8s.

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They run on 110-volt house current and plug into any grounded outlet. These sanders use a sleeve or ‘belt’ of abrasive that slips over the sanding drum—no crimping or tightening of abrasive required. These sanders are not the ‘tip-back’ style you may be familiar with.

The sanding mechanism of the Clarke EZ-8 is engaged with a feathering handle at the top of the machine, which gives the operator much finer control, reducing gouges and stop marks. EZ-8s are convenient because they can be broken down for transport and for hauling up and down stairs.

Our edgers are also made by Clarke, and we favor the B-2 model which has two speeds; the higher speed is more aggressive, and the gentler lower speed is used for the final pass with a fine-grit abrasive that’s great for reducing the appearance of dreaded edger swirl marks.

We also rent the Clarke Super-7 edger which is a bit lighter and easier to operate.

rental equipment in a jeep

Will your machines fit in the trunk of my car?

Absolutely. The EZ-8 breaks down into two sections, the handle and the motor. The motor measures 17″x16″x24″ and fits easily into a small trunk or back seat. Edgers travel in an oversize milk crate that can sit in any back seat.

EZ-8s weigh about 125 lbs. and edgers weight about 30 lbs.

Your website says you have “professional grade abrasives;” what does that mean?

We sell a much better range of grits than a general rental store.

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Most abrasive companies sell different ‘lines’ of abrasive, with the poorer quality papers generally marketed to the rental trades. This is lucrative for rental stores because you need to purchase a larger quantity of the lower quality sandpaper.

Other differences: lower quality abrasive belts have a paper backing that tends to stay stiff and rigid on the sander and can lead to chatter marks; professional grade abrasives are always cloth-backed and have a diagonal, wavy-line splice where the two edges are joined to form the tube.

Inferior abrasives have the abrasive mineral simply glued to a backing, rather than embedding the mineral in a resin that is bonded to the backing. One sign of a high-quality resin-bond abrasive is that the belt or disc has abrasive mineral right up the edge with no chips or areas of exposed backing.

We also sell a much better range of grits than a general rental store. Even 24-grit, which is a common starting grit for older floors in the Twin Cities, can be hard to come by, let alone 16-grit! We stock both grits for both drum and edger. If you’re not working in the Minneapolis/St. Paul area, you can order some in our online shop.

How do I know if I have enough floor left to sand?

Full thickness strip hardwood flooring can handle up to four sandings in its lifetime. Most hardwood floors that were installed in the ’20s and ’30s fell into disfavor by the late ’50s and were covered with carpet, effectively preserving them.

If your home dates from 1880-1915, you may have greater cause for worry because some of the floors installed prior to milling standardization were 3/8″ thick (and top-nailed to boot) and many of those floors are now too thin to sand.

If you have doubts, take a picture of your floor and, if possible, find a place where you can check its thickness and cross-section, and bring that information into the shop with you. Or get a one-on-one phone consultation with a hardwood flooring expert on our Help Hotline.

Pete's Hardwood Floor Help Hotline button

Do I really need to rent an edger? My belt sander can handle the edges…

We get this question daily. Everybody wants to use their favorite palm sander or belt sander to handle their floor’s perimeter. Or they love their Festool or have a great angle grinder.

Our answer is: edgers are always better.

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They are strong and heavy and cut flat because you don’t have to lean on them to make them work. Edgers typically weight 25-30 lbs. and run a .75 horse motor. Your belt sander, Festool, or angle grinder (shudder) will require the operator to push down while sanding.

This makes scoops and gouges in your wood and before you know it, your floor looks like the mogul hill at the ski slope. You should never have to push down on an edger; that’s how it keeps a floor so much flatter. Even floors that were left uneven by previous abuse by angle grinders can be levelled by an edger.

Keep in mind also that sandpaper your typical belt/angle/orbital sander doesn’t get much coarser than 40-grit. And 40-grit is just too gentle a starting point for many abused floors. We routinely start at 24-grit on older hardwood, and we have 16-grit and 12-grit ready just for gummy, shellac floors.

Order 16-grit sandpaper for your belt sander.

Can I sand off adhesive or backing from old linoleum? What about sanding painted floors? Should I be worried about asbestos or lead?

That leftover adhesive from old linoleum and vinyl is an absolute challenge to remove. We recommend that you at least attempt to remove some of it before you sand, but don’t bother trying adhesive remover (sanding is cheaper than that).

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  • First of all, measure the room—it’s much easier to estimate abrasive and finish needs if you know your square footage.
  • Next, remove all carpet, tack strip, carpet pad and especially the carpet staples (sanding over metal creates a spark hazard, and it can destroy the rubber drum or disc plate of a sander).
  • Remove or counter-sink any nails in the floor.
  • Remove all quarter-round; however, it’s not necessary to remove the baseboards. If your quarter-round is painted to your baseboard and removing it will mean a huge repainting or replacement job, you can skip it. You’ll just have to be more careful as you edge, and use a sharp scraper to clean the floor right up to the quarter round. You’ll also need to do some paint touchups on the quarter-round when you’re done.
  • Remove doors that open into the room.
  • Remove all furniture—yes, all of it—and take down window treatments and wall hangings.
  • Raise and secure any low-hanging chandeliers, or you’ll hit your head.
  • Fumes from oil-modified polyurethane can be lethal to small pets (birds, gerbils, guinea pigs; anything smaller than a rabbit) so we require that those animals be removed from the premises for the entire coating process. Larger pets can stay in the home, but we recommend securing them on another level to keep them away from the work area. If your pets are traumatized by strangers or noise, you might consider sending them on a short vacation until you’re done.
  • Take some “before” pictures so you can remember how bad your floors looked before you started (and because we give free t-shirts to anyone who brings in their before and after photos).

What do I need to do to get my floors ready to sand?

Follow these 9 steps.

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  • First of all, measure the room—it’s much easier to estimate abrasive and finish needs if you know your square footage.
  • Next, remove all carpet, tack strip, carpet pad and especially the carpet staples (sanding over metal creates a spark hazard, and it can destroy the rubber drum or disc plate of a sander).
  • Remove or counter-sink any nails in the floor.
  • Remove all quarter-round; however, it’s not necessary to remove the baseboards. If your quarter-round is painted to your baseboard and removing it will mean a huge repainting or replacement job, you can skip it. You’ll just have to be more careful as you edge, and use a sharp scraper to clean the floor right up to the quarter round. You’ll also need to do some paint touchups on the quarter-round when you’re done.
  • Remove doors that open into the room.
  • Remove all furniture—yes, all of it—and take down window treatments and wall hangings.
  • Raise and secure any low-hanging chandeliers, or you’ll hit your head.
  • Fumes from oil-modified polyurethane can be lethal to small pets (birds, gerbils, guinea pigs; anything smaller than a rabbit) so we require that those animals be removed from the premises for the entire coating process. Larger pets can stay in the home, but we recommend securing them on another level to keep them away from the work area. If your pets are traumatized by strangers or noise, you might consider sending them on a short vacation until you’re done.
  • Take some “before” pictures so you can remember how bad your floors looked before you started (and because we give free t-shirts to anyone who brings in their before and after photos).

Will these black stains sand out?

This is always a hard question. It is almost impossible to tell by looking if a stain will sand out. Dark stains from urine are the worst, largely because decomposing urine is a strong alkali and discolors the wood chemically.

However, it is always best to try to sand out a stain before resorting to more drastic measures; occasionally they do sand out. If the stains don’t lighten on sanding, patching is an option. Wood bleach is available, but we find that the results are so unpredictable that we aren’t willing to sell it.

If you do try to bleach, do not use household bleach—buy a product specifically designed for wood floors and do it 2-3 days before sanding so that the wood has time to dry.

Read our What pets do to hardwood floors for more details.

Should I use stripper on the floor before I sand to save on sandpaper?

Trust us; the money you “save” on sandpaper by using stripper will be spent ten times over on the chiropractic work you will need after trying to strip your floor on your hands and knees.

95% on the time it is better to just sand off any existing finish from that floor – that is what all those coarse sandpaper grits are designed for. Used wisely (which is where Pete’s comes in, so ask us about how to do this) sanding off old finish will be quicker, cheaper and easier.

Check your finish for lead first, though. Lead can be present, even in clear finishes like shellac or lacquer, and these finishes should NEVER be sanded off.

How dusty will it be?

Sanding is just not a dust-free process, and don’t let anyone tell you otherwise. 

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We strongly recommend using an attached vacuum (available for rent at Pete’s) on your edger because it tends to be the weakest link in the dust-control chain. The dust bag on the EZ-8 is surprisingly effective, as long as you empty the bag regularly.

No matter what you do, there will still be a layer of fine dust on horizontal surfaces and an even finer layer sticking to your walls. This is easily removed with a sponge and warm water.

If you are sanding your kitchen, even if you do rent an attached vacuum, it is still a good idea to either pack away all food and dishware or cover the cupboards and pantry with plastic.

We just bought a house and took out the carpet and the floors look really good—can we just buff them up a little?

First, just using a buffer to rub a dry pad or cloth over a floor will only help if you know that the finish is a fully intact, clean layer of wax.

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In that case only, the friction of the buffer will melt, respread and shine up the existing wax. But this won’t work for any solid finish like varnish, laquer, shellac or urethane (all of which are waaaay more likely to be under that carpet).

Now, If the finish on your floor is completely intact (no areas of wear or gray soiled patches at doorways) and you like the color, you can screen and recoat your floor. This means that you will sand the existing finish very lightly, just enough to create a bonding surface, and then apply one or maybe two layers of polyurethane over it.

However, this process will work only if the floor does not contain any wax residue (remember that many floors were routinely waxed in the ’50s and ’60s, sometimes even when they didn’t need wax). Test for wax by rubbing a clean, white cloth damped with paint thinner in a corner. If a brown, waxy residue is left on the cloth, a fresh coat of finish will not bond to that floor.

You might also check our Photo Gallery for examples of customers who thought their floors looked okay but decided to sand anyway. The improvement in the newly refinished floor is so drastic you may change your definition of what makes an acceptable floor.

What about radiators? Stairs?

We rent specialized machines for both in our MN store. Radiator edgers are designed to reach under even low radiators, though you will still need to hand scrape around legs and pipes. We also have a smaller edger for sanding stair treads. Unfortunately, there is no machine for doing the stair risers.

Should I fill in the cracks on the floor? When?

We limit the areas we fill to nail holes, dents, splintered board corners, and the short ‘board-end’ cracks. The cracks that run along the long edges of the board just aren’t worth filling; boards continue to swell and shrink along that dimension and any filler will quickly be reduced to kitty litter.

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Look at the photo—that is one ugly line of old, broken filler. We would rather see an honest gap between the boards than this half-baked mess.

If you use filler, don’t choose the kind that is applied after the job is done – this stays soft and comes out easily. Choose a hardening wood putty (like the Timbermate that we love) that matches the species of wood you have and apply it before you finish sanding.

We usually sand through the 36-grit stage, fill all our holes and gaps, and have lunch; by the time lunch is over, the filler is dry and ready to sand.

Read our very bossy article about using woodfiller on hardwood floors for more details.

Won’t my finish just automatically fill in all the gaps and voids in my floor?

Sorry, but no. Floor finishes are designed to be runny so they flow level into a film. Excess will flow into the gaps between your floor boards…and straight down to your subfloor.

Don’t try to put it on extra-thick, hoping it will fill up your nail holes with a neat, clear plastic plug, because it won’t work, and will stay uncured and milky-looking in spots where it is applied with any thickness. Use a hardening filler as decribed above and use it sparingly.

Read our very bossy article about using woodfiller on hardwood floors for more details.

What do I do once I’ve sanded the floor? I thought I was just supposed to stain it…

Be careful with the word ‘stain’—it’s the most abused word in the wood flooring industry. Most people use it to describe any coating that goes on the wood, but when we say ‘stain’ we mean a product that is applied to the floor to change its color, but is translucent enough to allow the wood grain to show through.

Stain alone is not a protective layer—it would scuff right off in a week! Check out our arguments against staining your floor.

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When most people say stain, what they really mean is the process of applying a protective finish to prevent damage to the floor from wear, water and dirt. The most common protective layer is polyurethane, but penetrating finishes such as Waterlox are also growing in popularity.

All of the systems that we sell involve applying a minimum of three coats to the floor. Both waterborne and oil-modified finishes are available. Stain can be used as a base coat under polyurethane if a darker floor is desired. Stain can be used with penetrating finishes as well, but is usually mixed with the finish before application.

A word of warning: Floors made from maple, birch, pine, or fir are notoriously difficult to stain evenly and well. We will actively discourage most do-it-yourselfers from attempting to stain those floors.

sanitaire 13 inch buffer

Do I always need to sand between coats of finish?

It varies according to what type of finish you are applying. Penetrating finishes do not require abrasion between coats.

Film-building finishes like polyurethanes or varnishes often require you to lightly sand between coats, but not always.

For some products, as long as you apply the finish within a certain elapsed time since the prior coat was applied, you can avoid intercoat abrasion entirely. If this appeals to you, check out the Pallmann line of finishes.

Keep in mind that ‘sanding’ really isn’t what you’re doing if you are between coats – you don’t have to go back and rent the drum sander or edger again. You need something much gentler. For a large area, this is best done with a low-speed flooring buffer and an abrasive screen. Small areas can be done just as effectively with a garden-variety pole sander (the tool normally used for sanding drywall seams) or a more fancy model.

Do I always have to sand parallel to the grain?

Yes, sanding parallel to the grain significantly reduces the appearances of scratches. There is an exception to this rule, though.

Check out ‘The Magical Exception of Cross Cutting‘ in our ‘How to determine your grit sequence; blog article.

Why do I have to lift the drum before I begin my backward pass?

If you were to leave the drum on the floor as you transitioned from going forward to going backward, you would find a little stop mark at the point where you changed direction.

In order for the machine to change direction, it has to stop. If it stops, it digs. So, for that momentary change of direction, the sanding drum must be off the floor.

Why do I have to do the floor in two sections?

The main reason is that you want to leave yourself plenty of room to maneuver the sander, especially when you’re backing up and getting into position for the next pass.

If you accidentally back into a wall, both you and the sander will stop dead and leave a deep gouge in the floor; if you start with your back to the wall, you leave a two-foot section (the area that you’re standing on) unsanded.

And you will quickly learn that doing a forward-backward pass over anything less than four feet is extremely tedious.

Why sand left to right?

The three wheels of the sander are positioned so that, if you move left to right, all three wheels are travelling level on already-sanded floor. This keeps the sanding cut level across the entire width of the drum.

If you move right to left, the left wheel is running on unsanded floor and so is higher than the other two wheels, causing the machine to cut more aggressively on the right side.

Do I do all my grits on the drum sander first, then switch to the edger?

The drum sander and the edger are always used ALTERNATELY. If you sand the center of your floor with 24-grit, then you will immediately edge that room with 20-grit. Sweep the floor, then change to a 36-grit belt on the drum sander, sand the main part of the floor, then edge the perimeter at 36-grit, and so on.

It will be easier to see exactly how much finish you have left to remove with the edger, which keeps the amount of edging you have to do to a minimum. You’ll also get a better blend of the straight scratch from the drum machine and the curved scratch from the edger if you alternate them.

How will I know if I have chosen the right grit to begin?

If your abrasive fills with old finish (called ‘glazing’ or ‘loading’) immediately into an initial cut, you need to switch to a coarser abrasive.

Otherwise, as long as the abrasive is cleaning the wood as you expect it to, continue with it—but not forever—see below for sandpaper limits.

60-grit belt

How will I know when to change the abrasive?

The abrasives we sell at Pete’s have very distinct lifespans; drum sander belts should last between 250 and 300 square feet each and edger discs should be changed every 20 linear feet.

If your paper is loading or glazing well before the paper’s scheduled expiration, that is a sign that you have started with too fine a grit for your job – throw away that loaded sandpaper and start with a fresh piece at a lower grit.

Customers often tell us that they continued to use their paper beyond its lifespan because, “it still felt sharp” or “it was still producing dust.” Neither of these conditions is a trustworthy was to evaluate your abrasive. Remember that the sharper your paper, the more quickly and efficiently it cuts.

As one very wise customer recently told us: sandpaper is cheap, time is expensive.

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So, calls are free and unlimited if you:
But please use our cheap and splendid Help Hotline consulting service if you:
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We have everything you need, online or in our St. Paul, MN store.

Visit our online store from the comfort of your sofa or visit our cute store at 186 Fairview Ave N in St. Paul, MN. We've got everything you need for your project, and friendly people to answer your questions. 

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The magical exception of cross-cutting.

If you have a severely scarred, uneven, water-damaged or painted floor then you may want to consider not only starting with a coarse grit, but sanding at an angle to the grain.

This is an important exception to the rule of always sanding with the grain of the wood.

It only applies during the rough sand stage, but it is a very efficient way to speed the process of cleaning and leveling an old floor.

Because of wood’s natural tendency to shred and splinter when it is sanded off-grain, the sander can remove more wood with the same amount of effort when positioned at an angle. The angle does not need to be drastic; sanding just 10-15° off parallel is enough.

The downside of using this procedure is that, after you make an entire pass at an angle, you must follow it with another pass parallel to the grain at the same grit. So, if you do a 24-grit cross-cut pass, your sanding sequence would be 24 diagonal > 24 straight > 36 > 60 > 80.

Newly installed floors can be rough-sanded with 36-grit parallel to the grain.

The rule to remember is that, no matter what grit you choose as your starting point, you must sand, in order, with every grit that is finer than your starting point.

So, if you start with 16-grit, you cannot jump to 36grit; you must go 16 > 24 > 36 > 60 > 80 on both machines.

If you start at 24-grit, you cannot jump to 60; you must go 24 > 36 > 60 > 80 on both machines.