Let Me Talk You Out of Staining Your Floor

How can I help you today?

Well, I’d like some advice on staining my floors.

Very good.  Can you tell me what species of wood your floor is, because there are some woods that don’t take stain well.  And it would be helpful to know how you plan to sand the floor, because stain pigment can reveal sanding imperfections…

No, you don’t seem to understand what I’m doing.  I want to varnish the floor.

Oh, you aren’t trying to darken the floor? You just want to seal it against water and wear?

Yeah, that’s what I said: I want to stain the floor.

�

Part of the misunderstanding here stems from the fact that in the wood flooring industry stain has a very narrow meaning: it refers to solid particles of pigment suspended in a solvent, applied to wood to darken or change its natural color.  Wood flooring professionals tend to assume that everyone knows that stain is quite different from finish, which is the generic term for any substance that can seal the porous surface of wood and provide a reflective sheen.

     But semantics are only part of the problem; the real foundation of this misunderstanding is the widely held assumption that all wood floors should be darkened or colored and that this is a routine and simple part of do-it-yourself floor finishing.  Most of our customers think that staining a floor is easier than painting a wall.  How we wish that it were so.

Floor staining is difficult, finicky work, with unpredictable results.  Even flooring professionals lose sleep over this process because there are dozens of variables that can make staining go wrong.  And when it does go wrong, the only solution is to re-sand the floor and start all over from the beginning.  Staining floors, especially for first-time do-it-yourselfers, is a tricky business.  That’s why we do our utmost to talk you out of it.  Here are four big reasons why:

3. Bleedback is ugly.

Stain is applied differently than almost any other finish: it is usually rubbed onto the wood with a soft cloth and then immediately wiped off.  The amount of stain that a floor can absorb is finite; the floor will not get darker if you flood it with an excess of stain or apply a second coat.  Using excess amounts or multiple coats of stain can lead to bleedback, where stain wicks back up to the surface of the board as solvent begins to evaporate.  Bleedback can also occur after a finish coat has been applied to a layer of stain that has pockets of uncured stain in the gaps between the boards; the pigment seeps up and into the clear finish, leaving a cloudy streak.

You can also get something similar to bleedback if you coat over a dried stain with an incompatible finish.  If your finish contains a solvent that can re-dissolve the binder in your stain, the particles of stain pigment (even if they were fully dry to the touch before top-coating) will blotch or seep into your finish.  Using stains and finishes that are advertised as compatible (like our products) is the most foolproof way to avoid solvent interference.

4. Stain adds waiting time.  A lot of waiting time.

Latex paints have set very high expectations about drying and recoat times—expectations you need to leave behind if you are staining a floor.  This is because stain is just the first step in the process of finishing your floor.  Pigments alone do not provide much in the way of abrasion or solvent resistance, so most people add two or three layers of some clear, protective finish over stain.  But if your stain coat is not completely dry, it will not allow any subsequent coats to bond.  This leads to a sticky, ugly mess that must be sanded off and re-stained.  Given the dire consequences of coating over stain too soon, we recommend that you allow stain to dry for 48 hours even under the ideal heat, humidity, and air exchange conditions specified by the manufacturer.  All stains dry by solvent evaporation; if your windows are closed or if the heat is set too low or turned off, the solvent cannot evaporate, and the stain takes longer to dry.  Low temperatures, high humidity, using too much stain, and not wiping it off thoroughly will all lengthen the drying times.  For example, if you are staining during a thunderstorm in August, you could wait up to four days before it is safe to topcoat that stain—four days, plus a day for each coat of finish, and then a day to allow the last finish coat to cure.  This is when you ask yourself whether you want a dark-stained floor badly enough to wait a full week before you can move furniture back into your room.

1. Stain makes sander scratch shockingly visible.

The most important reason to think carefully about staining is that it accentuates even minor flaws in your sanding job—flaws that would be undetectable in a clear or natural-finished floor.  Remember, stain is made of fairly large particles of color, called “pigment.”  Bob Flexner in Understanding Wood Finishing puts it this way: “Pigment colors wood by lodging in depressions, such as pores, scratches and gouges.  The larger the cavity, the greater the amount of pigment that will lodge there, and the darker and more opaque the cavity becomes.”  Unfortunately, inexperienced sanders (the very people who are most likely to want to stain their floors because they assume it is easy to do) tend to leave many such deep cavities, scratches, and gouges in the floors they sand.  When the stain is rubbed into the wood, the color is absorbed more deeply along the scratch lines than in the surrounding wood.  In other words, staining a floor (sanded by a beginner) is a lot like tattooing a floor.  To make things worse, the edger (see “Sanding 101: Using the Edger”) is particularly prone to leaving cross-grain scratches that, when filled with stain, are still more obvious because they run against the main grain direction of the floor.  There is no greater proof of an amateur job than edger swirl and cross-grain scratches that have been highlighted with stain.

2. Some woods species are not meant to be stained.

Before applying stain to your wood floor, you need to know what species it is.  Floors made of maple, birch, and coniferous woods (especially pine or fir) are all very difficult to stain evenly.  Maple and birch are tight-grained woods with very small pores, and the density of the pore wall fibers varies drastically.  In other words, the particles of stain pigment have fewer places where they can wedge themselves and those places are not regularly spread through the wood.

Pine has the same variations in pore wall density, but to make matters worse, coniferous wood fibers contain resin or sap that actively resists stain!  Even though stain manufacturers provide sample chips of stained maple or pine, do not be fooled; those sweet little chips are easy to stain precisely because they are little.  Over a large, uninterrupted area like a floor, blotching and mottling will be much more apparent.

Red oak and white oak floors absorb stain more uniformly, but be aware that there is a difference between the density of earlywood (or springwood), and latewood of these species.  As you can see from the photo, the more porous springwood stains considerably darker than the dense latewood, giving the boards a distinct zebra-striped look.

�

Once a customer understands the ramifications of staining a floor, the idea of a clear-coat finish starts to look very attractive.  However, if you are one of those stalwart types who, despite all the warnings, declares that you are ready for the challenges of stain, there are some things you can do to make the process easier and more successful.  If you are one of those types, proceed to the article, “Yes, I Know Staining Is a Headache.  I Am Going to Try It Anyway.”