We wanted a zero-VOC floor finish.


What is a zero-VOC finish, and why is it even desirable?

Zero VOC means no Volatile Organic Compounds – those long-chain hydrocarbons that contribute to interior air pollution and can combine with nitrogen oxides to form ground-level ozone – are released as the finish cures.

A zero-VOC finish is hard to find in the floor coating industry and we had been searching for one for a while. It’s not exactly clear why the floor finishing business is so far behind the paint industry – VOC-free paints have been available in mainstream retail for at least two years.

Flooring finishes seem to rely heavily on those volatile petroleum-distillate-based solvents that keep the solids and resins in solution until applied but evaporate quickly to allow the finish to dry and cure in a reasonable time.

But mineral spirits and petroleum distillates release high levels of VOCs that can cause eye, skin, nose and throat irritation, and they are neurotoxins that may depress or damage the brain and nervous system. Short-term exposure to VOCs can cause dizziness, headache, drowsiness and nausea.


While you can use a respirator to minimize your risk during the actual application of these finishes, the VOCs can linger in upholstery fabrics or curtains and even in the air after the finishes have dried.

Even waterborne finishes are not completely VOC-free and can also release unspecified amounts of ammoniates and biocides as they cure. So we really needed to have another option for our customers who are pregnant or respiratorily sensitive.

Rubio Monocoat is a mixture of linseed oil and engineered waxes and its Material Safety Data Sheets list it as a non-hazardous substance containing 0 g/L VOCs (by comparison, a typical gallon of a solvent-based polyurethane will release 3.8 pounds of volatile organic compounds into the air. Ouch.)

So, Monocoat definitely delivers as non-toxic and highly sustainable finish. It’s coverage rate is also fantastic, which means you do more with less product which reduces the energy needed to ship and handle the product. But does it work on floors? Read on:

How does it handle spills?

testing monocoat

The floor finishes we sell need to perform under the conditions of real life and we expect even non-toxic finishes to handle coffee spills, red wine, and the occasional pet accident.

Rubio Monocoat is a viable alternative to polyurethane only if it actually protects the floor. Carnauba wax, for example, is also a zero-VOC finish, but it is next to worthless as a floor protectant and so we won’t sell or recommend it.

In the tests we’ve done in the store, the Monocoat had no problem resisting the most common household spills. Cola, gin, coffee and yes, urine, left no discernible stain or etch in the finish after 24 hours. So, we decided to up the ante and put undiluted household ammonia on some Monocoat Pine and Natural, two of the colored oils.

We chose ammonia because decomposing pet urine eventually becomes ammonia as it decomposes and we know that a pet accident will, if overlooked, leave deep black stains on most coated floors.

We let the ammonia sit on the Monocoat for about two hours and it did leave a dark stain on the wood. The stain lightened after gentle abrasion and was barely discernible after we recoated the sanded spot.

Now, ammonia is a strong alkali and it is unlikely that you would be using it, undiluted, on your floor. For comparison, we did the same test with the ammonia on a sample of wood that had three layers of polyurethane and it took two hours for the ammonia to penetrate.

While this is clear evidence that the polyurethane is a thicker, more protective coating, the ammonia did eventually penetrate it.  And the small ammonia stain on the poly was much harder to fix because polyurethane doesn’t blend well into itself. With a polyurethane-finished floor, you must sand the entire affected board (or boards) to their edges and recoat all the way to those edges as well, or the repair will be very visible.

So, if you are planning to allow pet stains to linger on your floor (not something we recommend, but life happens), you will actually have an easier time correcting them if you have a Rubio Monocoat floor than if you have polyurethane.

But what about foot traffic?

rubio sample wall 2014

This is the aspect of Rubio Monocoat that continues to make us the most skeptical. The Monocoat oil is designed to be a one-coat finish (hence the name). One coat? We have not encountered a floor finish in our 17 years in business that provides adequate protection from wear and abrasion with just one coat – certainly not through a snowy, salty, gritty Minnesota winter.

When we were first considering selling this product, we decided to use ourselves as the guinea pig and applied Monocoat right in the busiest traffic area of our shop.That was over six years ago and, despite our initial skepticism, we been extremely impressed by how well Monocoat holds up in our tough commercial environment (we sell sandpaper for a living – think of how much abrasive grit we have all over our floors).

What we find even more impressive is how easy it easy to touch up the floor when wear begins to appear. The Monocoat manufacturers explain it like this: if, during the course of daily living, scratches or wear appear in that single bonded layer, additional Monocoat oil is wiped over the worn portion. It bonds only to the wood that has been exposed by wear, but not to the adjacent coated wood. The excess is wiped off and the problem is solved without moving furniture or renting a buffer or applying a coat to the entire floor. the wax component of this finish has been re-engineered so that its shape matches the molecular shape of exposed raw wood. The liquid product is wiped on the raw wood, and only bonds to uncoated wood, and the rest is wiped away.

We’ve had harsh wear, spills and an ice dam that flooded our Rubio floor under a piece of metal equipment that left a nasty black stain. Everything sanded out and healed back into the existing floor with a little rub of fresh oil.

mark plus rubio samples 2

All the questions you’ve ever wanted to ask about Rubio…

 After six years of using and selling the Rubio Monocoat line, we still adore it.  But we haven’t drunk all the Rubio kool-aid.  It is a great product, but it is not perfect for everyone.  Read our long-winded and very frank answers to the most common Rubio questions below.

Does it really hold up?

Rubio holds up extraordinarily well, if it is maintained.  This means that you must address dry or worn-looking areas as they appear.  Vulnerable areas around exterior doors or in front of the kitchen sink should be addressed (or at the very least inspected) at least once a year.  But Rubio is far easier to maintain than other finishes because you can just touch up the areas that need work; you don’t even have to more furniture if you don’t want to. You have three different options for refreshing your Monocoat, depending on the level of abuse you’ve given it – click here for guidance on which maintenance procedure you need.

Most people, as soon as we start discussing the need for regular maintenance, will look a little crestfallen and say that if they have to maintain the Rubio, they don’t want it.  There seems to be an assumption that, if a coating needs maintenance, it must be low quality. But when your car dealer talks about regular maintenance and oil changes for a vehicle, you don’t decide not to buy it.  Maintenance is a part of all good investments; even the toughest polyurethanes will “ugly out” and wear down over time and need to be top-coated to remain protective and attractive.  Rubio may need more frequent maintenance than polyurethane, but the maintenance procedures are much easier and less disruptive (and much less smelly!) than film-building finishes.

46 colors!  I’ll be able to exactly match my floor to my countertops!

Well yes, and no.  The colors are gorgeous and you can blend them together any way you like, which gives you, theoretically, an infinite number of colors to choose from. But we have found that some of these colors are so similar that the nuance of their differences are lost when applied to a typical floor where the wood grain varies widely from board to board.  Rubio is not like paint; it will not give you the same color on every floor board, because every board is different.  If this natural variation is something you cannot tolerate, Rubio is not a good DIY choice for you (even professionals can find it challenging to create perfect, matching uniformity of color on all woods).  You should think of Rubio Monocoat like perfume or cologne, where the same scent will smell a little different on each person, based on their body chemistry.  Likewise, the final color of Rubio on your floor or project will be determined by the species, age, grade and sanding grit sequence of your own wood.

Do you carry all 46 colors of Rubio?

We stock 26 of the Rubio colors: Black, Castle Brown, Charcoal, Cherry, Chocolate, Cotton White, Dark Oak, Havanna, Mahogany, Natural, Oak, Pure, Pine, Oyster, Savannah, Sky Grey, Smoke, Smoke 5%, Slate Grey, Stone, Super White, Vanilla, Walnut, White, White 5%, and Titanium Grey.

We also stock the exterior oil in Pure, the Smoke and Fumed Pre-treatments, Refresh spray, Universal Maintenance Oil and the Rubio Soap in both concentrate and spray form.

Why is Rubio so expensive?

It’s really not expensive, especially compared to quality polyurethane.  One 1.3L of Rubio Pure at $160 is enough for 600 sqft of flooring.  To get three coats of polyurethane on that same area would require four gallons of poly and cost closer to $200. Rubio seems expensive because the cost per liter is high, but the coverage rate is so good, you need much less product to do the same area.

Can I apply Rubio over my existing finish, or do I have to sand my floors first?

You must sand your floors down to bare, clean wood before you can apply Rubio.  Rubio’s cure reaction needs both wood and oxygen to form a barrier; it won’t permanently bond to other finishes or non-wood surfaces.

Is Rubio applied like polyurethane or paint?

Neither.  Rubio behaves more like a wax than paint or polyurethane, and so we use a buffer to apply it to floors so that it can be spread easily.  If you treat it like paint and brush it on and leave it to dry, it will be much too thick and may never properly cure.

So, working in areas about 80sqft at a time, you will use a buffer to spread the Rubio into every inch of exposed wood fiber.  Then after about 8 minutes of buffing, you will change to a fresh, more absorptive, pad and buff off any oil that did not bond to the wood.

We cannot overstate the importance of spreading the Rubio at the correct coverage rate: never, ever leave enough Rubio on the wood to form a thick coating – it will remain sticky for weeks, and maybe forever. Click here for the full application procedure.

Is this really non-toxic?  How does it smell?

This is one aspect of Rubio about which we have absolutely no reservations.  Even very chemically sensitive customers have successfully applied Rubio Monocoat.  The material smells a little bit like honey as it is being applied, and that smell lingers slightly for the five-day cure period.  Cured Rubio smells like nothing.  Cured Rubio is also cut-safe for countertops and cutting boards. Click here for all the Rubio MSDS sheets

Is Rubio really as easy to fix or repair as they say it is?

Some colors more so than others.  The Pure is the most foolproof of all – no matter how we’ve sanded out problem areas (and even when we’ve done it completely wrong) it has blended back into the surrounding finish with ease. The darker colored oils are more difficult because they behave more like stain and the intensity of their color is more dependent on the underlying texture of the wood and the sanding grits you use.  Sometimes the process of spot-fixing inadvertently over-polishes the wood or polishes the linseed oil into the wood grain, both of which prevent the new Rubio from soaking in as deeply as the original coat, which makes the repaired area look lighter.  You can correct for this by finishing the spot-fixed area with a relatively coarse grit, sanded with the grain by hand, so it will take more Rubio and darken to the same level as the existing floor.  But it can take some trial and error to find the grit that will allow you a color match to the old Rubio.

Do I HAVE to rent a buffer?

If you’re applying or refreshing Rubio on a floor, renting a buffer for your job is worth every penny. It allows you to work standing up and will speed up the process by a factor of four or five.  Furniture, counters and woodwork, however, are much easier to Rubio by hand.

You seem to be very biased against Rubio on fir and pine. Why?

First, to be clear, Rubio behaves exactly as it is supposed on fir, pine and other conifers; it bonds beautifully to the wood and resists solvents and abrasion as it would on any other wood floor.

But, our first concern about using Rubio on those softer woods is the splinter risk. Fir and pine are less dense than other American hardwoods and tend to produce slivers at the board edges. The hardwax/oil combination is wonderful against solvents and abrasion, but it isn’t thick enough to seal down the splinters or slivers.

Our  other concern about Rubio on fir or pine is how the colored oils look on those woods.  Coarse, resiny woods don’t take stain or pigmentation easily and Rubio is no exception.  In particular, the mid-dark Rubio tones (Oak, Dark Oak, Walnut, Mahogany, Smoked Oak, Dark Oak and Cherry) look muddy and blotchy.  The Oak, Dark Oak and Smoked Oak also take on a distinct greenish tint on pine, which we find especially unattractive.  The lighter oils like Pure, Natural, 5% White, 5% Smoke, Pine tend to look more uniform and bright.  We have had some success using the Smoke Pretreatment under the very dark colors like Chocolate and Charcoal to create creamy, even and opaque tones on pine and fir.  The challenge of pigmenting fir and pine is not unique to Rubio and should not be considered a defect of the product, but a reality of those wood species.

Why do I need the accelerator?

The accelerator is a magic substance that allows the Rubio to reach full cure in five days instead of three weeks.  Three weeks is a long time to try to baby your floor.  Most people just can’t do it, and end up putting three years worth of wear on the floor in those first three weeks when the finish is still vulnerable.  The accelerator helps enormously with that.  The same is true if you are doing countertops or bathroom vanities – you want that Rubio to cure as quickly as possible so that the water cannot get into your wood.  If you are just coating woodwork or regular furniture, you can probably skip the accelerator, but very few places sell the oil without it.

Update from Rubio USA December 2016: But it turns out that accelerator does more than improve cure times – it makes the final cured surface harder and allows it to perform better (meaning it lasts longer before it needs renovation). So, when people ask if they can skip the accelerator, we say no, even if they are doing furniture or countertops that don’t receive foot traffic. But, to be clear, Rubio will still eventually harden without the Accelerator, just not as fast or as well.

I’ve read that some people recommend water-popping your wood before applying the Rubio – why would I do that?

Any time you wet wood, the water causes the grain to swell and open.  This creates roughness and, in doing so, increases the surface area of that wood.  We find that water-popped floors actually hold more Rubio and stand up to wear longer, as well as looking more uniform.  However, our distributor does not recommend  this procedure because they are concerned that customers will not water-pop evenly, which will give the Rubio an uneven appearance. So, we are being very naughty when we advocate water-popping, but it hasn’t stopped us.  If you choose to water-pop, be sure to use distilled water, and apply it very lightly, preferably with a spray bottle or a clean pesticide sprayer, and be sure to let it dry thoroughly before applying your Rubio oil.  Also, be aware that water-popped Rubio floors will feel rougher to the touch than non-popped floors.

Can I use Rubio on furniture and countertops?

Absolutely yes!  It is food and cut safe for countertops and a joy to apply to furniture and woodwork.  The ease of maintenance makes it a great choice for even bathroom and kitchen countertops because it is so easy to touch up.

I just want the clear Rubio…

Ah, yes, one of the things that frustrates us about the Rubio is how confusing the color names are.  Here are some tips that may help:

  • The product they call Pure is NOT clear.  It has no added pigment, but the inherent honey color of the linseed oil will amber your wood significantly.
  • The color called Natural is not clear either; it is, in fact, Pure with a small amount of White added to cancel out its yellow/amber color. The intended effect is to make the wood look as though there is absolutely nothing on it, but sometimes the white pigment will catch in the softer grain and can make wood look a little pickled.
  • 5% White actually has slightly less white than Natural and tends to make wood look less pickled and ‘white-washy” than Natural.  More natural than Natural, if you will.
  • There is, in fact, no Rubio called “Clear” sold in the US
  • Charcoal is darker, more opaque and blacker than the color Black.
  • Both Silver Grey and Charcoal have a little bit of metallic sparkle

Do you guys have any tips on how long to wait before putting tape on a Rubio floor to keep paint off the oil? Plus what tape is recommended?

When we first presented this question to Rubio USA, they told us, in no uncertain terms, that tape is forbidden on Rubio, no matter how cured it is. Which is the manufacturer’s way of protecting themselves, but makes Rubio oil seem delicate and temperamental. Which it is NOT.  To be safe, we would use 3M orange core tape, on cured Rubio only, and we wouldn’t let it sit for more than an hour. However, we have had customers use generic blue painter’s tape on Rubio that was only 24 hours cured and leave it for 24 hours, without visible tape issues.  When in doubt, test a small area first.

We sanded our old-growth, pre-1900 pine floors in preparation for Rubio, and sap started oozing up out of the grain! What do we do? Will the Rubio still bond to our floor?

Pine that wasn’t kiln-dried to “set” or crystallize the resins can still weep sap, even a hundred years later! Sanding heats up the wood and allows the semi-liquid resins to move around, which explains why you have sap coming out of otherwise mature, stable wood. But, you’re right to be concerned: Rubio won’t bond well to sap. Finish the sanding and allow the wood to dry and cool. Then wipe the surface thoroughly with the Rubio Raw Wood Cleaner right before you apply the oil.

Can I use the Rubio Hybrid Wood Protector on pressure-treated or green-treated lumber?

Rubio recommends waiting six months to a year to allow pressure-treated or green-treated lumber to dry and turn a bit grey before using the exterior wood cleaner and then the exterior oil. They do not recommend using the Hybrid Wood Protector on water-repellant treated pine.

Rubio Exterior doesn’t come with Accelerator – how come?

When the Rubio Hybrid Exterior oil was first formulated, Rubio didn’t think it benefited from Accelerator, but they now recommend the addition of a 10:1 oil to accelerator ratio to improve long-term performance. They have begun to carry their accelerator in a 100mL bottle specifically for adding to single liters of their Exterior product.

Can I use stain conditioner on fir or maple before I use a colored Rubio to try to control the natural blotchiness of those woods?

Unfortunately, that won’t help. Stain conditioner is nothing more than a thinned-down build finish -usually a varnish of some kind. But, as soon as wood has even a thin layer of finish on it, Rubio won’t bond to it. But there is hope. Traditional stains are harder to lay evenly on blotch-prone woods because they are mostly solvent. When you have a small amount of pigment carried in a large amount of solvent, it is harder to control where the pigment goes. Heck, it’s hard enough to keep the stain stirred evenly during application! Rubio has much less solvent, so it’s inherently easier to control the pigment and apply it more evenly. The other tip is that water-popping any wood open the grain enough to allow more pigment to “catch” in the nice, uneven surface, which allows greater density of evenness of pigment. This technique works for stain, but works especially well with Rubio – and water is practically free! (Water-pop wood using, preferably with distilled water dispensed in a garden-style pump sprayer, saturating the wood until the water beads. Do not wipe or mop. Allow to dry at least four hours, but temperature and humidity could extend drying time).

I did a coat of Rubio on my red birch floor and it still looks dry and thirsty. Help!

Yes, this is a recent update from Rubio. On softer, more absorbent wood species like walnut, birch, fir, or pine, a second application is recommended. This should be done at least 12 hours after the initial coat was applied. This second coat will require significantly less product.

I love the dark Rubio colors like Charcoal and Chocolate, but I find them more difficult to apply and to repair. Why are they more challenging than other Rubio colors?

Charcoal and Chocolate are indeed the two most opaque, pigment-heavy Rubio colors. This makes the oil thicker and more difficult to apply. Rubio has taken a page from some of its competitors and is recommending using a rubber squeegee or wide metal trowel for applying Charcoal and Chocolate to help drive it into the wood. This does add a step because you must use the red pad on the buffer after the trowel step, and then use the white pad to buff off as usual. This is especially important on the edges – it is almost impossible to get Charcoal or Chocolate into the wood just rubbing it in by hand, which is what you normally do for areas you can’t reach with the buffer. Using a trowel to push the Rubio into the wood (both around the edges and in the field) will vastly improve the uniformity of penetration of Rubio’s darkest colors.

Also, keep in mind that the thicker oils cover significantly less area than other Rubio colors. Charcoal and Chocolate will do, at best, 400 sqft per 1.3-liter container, and if you water-pop, the coverage drops to 300 sqft per 1.3 liters.

Is Rubio more difficult to apply when the weather is warm?

Higher temperatures usually allow Rubio to flow better and cover more area, but the chemical reaction between oxygen and Rubio’s engineered waxes happens faster when it gets warmer, so the Rubio will get tacky faster in hot weather. The solution is to work in small sections that you can complete more quickly.

Rubio is a zero VOC finish with limited solvents – so do I have to worry about air circulation while it dries?

Absolutely yes! Air exchange is just as important for Rubio as for more traditional finishes. Maintain 65 degrees and keep windows open (or at least gapped in cold weather) during the five-day cure period. Keep doors between rooms open and turn on those ceiling fans! Dust won’t stick to fresh Rubio (at least not in the same way it sticks to polyurethane and makes it rough) so moving air always improves cure time.

How long do I have to wait before I walk on my freshly applied Rubio floor?

If you are wearing clean socks you can walk across your Rubio floor as soon as it is applied. But notice I said, “Walk across,” not “Move in and have a party.”

So, if you have only one bathroom and a freshly coated Rubio lies between you and that necessity, put on a pair of clean socks that you can throw away (because they will get oily on the bottom) and walk carefully along the edges of the space to your restroom. But Rubio recommends that you wait 36 hours before resuming shoes-on foot traffic and replacement of furniture. Wait 5 days before you use water or cleaner on your floor, and to be extra-safe, wait 5 more days before you replace large area rugs.