Sanding and preparing wood prior to staining is a necessary process to ensure the wood takes in as much of the stain as possible, yet many forego this crucial step. Neglecting to sand and prepare the wood can lead to a finish lighter in color than was intended, spotty or uneven color, or even a stain that fades over time. So, how do you sand and prepare wood before staining?
To sand and prepare wood before staining, first identify the type and grit of sandpaper to be used. Sand the wood twice with a medium grit sandpaper (100 to 120-grit) and twice with a fine grit sandpaper to remove any imperfections and prepare the surface for stain. Clean the wood with a damp rag twice, which serves to both remove any debris and condition the wood. Finally, apply your choice of pre-stain wood conditioner, washcoat, black tea stain or mineral spirits to prepare the fibers in the wood to accept stain.
Wood projects ranging from a new piece of furniture built from scratch to an antique refurbish project or an exterior fence to indoor wood floors all require sanding and solid preparation prior to staining. Follow the steps laid forth in the remainder of this article to ensure your wood projects are finished properly in order to stand the test of time.
Why Do I Need to Sand Before Staining?
There are many reasons to take your time to prepare wood properly prior to staining, the foremost being so the wood will accept, or soak in, as much of the stain as possible. Certain types of wood, like pine, maple, cherry and birch, are extremely difficult to stain due to the composition of the wood itself.
Sanding the wood properly prior to administering stain, in conjunction with other steps that we will cover shortly, will allow the stain to soak evenly throughout the wood, providing an even finish that will best hold up to the wear and tear furniture is subjected to.
Additionally, sanding removes any imperfections on the surface of the wood. This includes any surface blemishes, dents, scratches, and dings that could be difficult to spot with a naked eye, but will stick out like a sore thumb once stain is applied.
Contrary to prepping wood for paint, where the goal is to rough the surface of the wood enough to allow a good surface for the paint to adhere to, the purpose of sanding wood for stain is to create as good a surface as possible because the stain will not hide things that paint will.
Thusly, it is important to sand the wood down to “new wood,” or wood that doesn’t already have paint, stain, or sealer soaked into it or on top of it. So, what sandpaper and/or power tools should be used to sand before staining?
Sanding Techniques
First off, ensure you sand your project in a well-ventilated area with a respirator or a mask. If completing your project in the heat of the summer, bring it into a garage or under a canopy (basically, anywhere out of direct sunlight, which could affect the way different foreign substances absorb into the wood. Furthermore, don’t leave the wood in direct sunlight for too long. All wood and materials should be as close to room temperature as possible for the best results.
The grit of sandpaper to be used depends largely on the condition of the wood. If you need to remove a layer of paint, stain or sealer, start with an 80-grit sandpaper and finish the sanding process with two passes of 120-grit to smooth the surface.
If you are working with new wood or wood that hasn’t been painted, stained or sealed, start with 100-grit and finish with two passes of 120-grit.
Handheld orbital sanders work great in conjunction with 80 to 100-grit sandpaper to remove anything on the surface of the wood, but you run the risk of creating grooves and surface blemishes if you are too aggressive. If using an orbital sander, I recommend using 100-grit sandpaper and being extremely careful not to stay on one spot as you sand. Utilize continuous motions and track where you’ve already sanded to mitigate this risk.
Belt sanders are in the same vein, in that you run the risk of uneven surfaces by removing too much off the surface. Use the same techniques previously discussed to mitigate the risk.
The best electric sanders to use for woodworking are agitator sanders. Agitator sanders have a small motor inside that turns to create a quick back-and-forth motion. They are typically much less aggressive and are more forgiving to those that lack experience with electric sanders.
Regardless of the electric sander you use, I highly recommend making two passes with a handheld sander, sanding block, or sheet sandpaper in 120-grit or finer.
Finishing the sanding process manually will give you more control over the final finish and provides a larger margin for error. It requires a small amount of additional effort, but will only set you back five to ten minutes and is well worth the sore forearm in the morning.
End-grains, or the ends of the piece of wood where a cut was made, tend to soak up more stain than the other sides. A little extra attention to these areas when sanding will help to ensure uniform stain coverage for the finished product.
Areas of wood that aren’t flat will require a sheet of sandpaper that can contour to the shape of the wood for an even sanding. Simply purchase sandpaper sheets in 120 and 240-grit for these areas.
To check if you have sanded the wood properly, run a dry rag over each side to see if it snags on any pieces of protruding splinters. If it snags, go back over that area with the electric sander, sanding block, or sheet sandpaper and check again. Repeat if necessary to ensure no snags.
Finally, ensure you sand in the direction of the grain of the wood. Sanding perpendicular to the grain can create an uneven surface that will become evident once the stain is applied.
Inspect the Wood for Any Defects
Defects in the wood such as splits, nail or screw holes, or snags can affect how the wood takes stain in addition to remaining visually significant once stain is applied. Consider the benefits of stainable wood filler or leaving the wood as-is and simply focusing on additional sanding where needed.
Other imperfections or defects in wood like knots, pest holes, or dents will be highlighted once stain is applied. That could be a pro or a con, depending on personal taste, but knowing where they are located will help you plan how to orient the wood for the finished product.
Cleaning the Wood Prior to Staining
Arguably more important than the sanding itself is the preparation process. A little bit of science is needed to better understand why. As wood is subject to moisture its fibers swell, creating an environment where foreign materials can penetrate deeper. In our case, the foreign material is the stain.
With the understanding of what happens to wood when it is subject to moisture, we can begin to understand why we do this next step. After sanding the wood down to “new wood” and creating an even surface with a fine grit sandpaper, take a damp-but-not-dripping rag or cloth and clean off the surface.
Ensure you rinse the rag between passes, which also serves to remove all debris left behind from the sanding process. Let the wood sit for ten minutes prior to proceeding to the next step.
Different Methods of Preparing Wood for Stain
After you have cleaned the wood with a damp rag following the sanding process, it is time to prep the wood for stain. There are many different wood conditioners available on the market. We will go over the pros and cons of each below. Application of all six of these products is no different than applying the stain itself.
My personal technique is to use a clean rag to apply stain as it allows me to better control the amount being applied when compared to a paint brush, foam brush, or stain application pad. To expound a little more, foam brushes and stain application pads soak up too much stain which could lead to an uneven application. Paint brushes are on the other side of the spectrum and soak up too little stain.
As was alluded to above, pay particular attention to areas of end-grain which typically absorb additional stain, making them appear darker than the rest of the wood. In addition to extra sanding, ensure these areas are covered with pre-stain treatment.
Finally, before we get to the individual products, my personal technique is to condition any wood prior to staining, not just the porous ones as previously described. From my experience, the desired color and darkness simply come out best when treating the wood prior to staining.
Pre-Stain Wood Conditioner (24-hour cure time)
The purpose of pre-stain wood conditioner is to condition the fibers of the wood to accept an even coat of stain. This is especially true for porous woods like the few we uncovered previously (pine, maple, cherry and birch). Products indicating a 24-hour cure time should be interpreted as “let dry completely prior to staining,” meaning you don’t really need to wait a full 24 hours. Simply wait until the wood is completely dry prior applying your first coat of stain.
If you don’t allow the wood to completely cure, or dry, prior to staining, you will get a finished product with a spotty finish. The reasoning for this is due to the reaction of the wood conditioner with the wood and with any stain it comes into contact with.
If there is ever any doubt, simply plan to apply the pre-stain wood conditioner and let it cure overnight. This will give the wood ample time to soak in the conditioner and dry before you attempt the staining process.
Pre-Stain Wood Conditioner (15-minute cure time)
The big difference with 15-minute cure time pre-stain conditioner is obviously the time it takes for the wood to absorb the mixture. To me, these products are slightly misleading in that they give the sense of security of fast dry times without explaining the process of what is actually going on with your wood.
For that reason, I highly recommend letting your wood sit overnight prior to applying any stain, regardless of the time it says on the can!
Yes, the 15-minute pre-stain conditioner will dry faster than the 24-hour varieties, but you want to make sure that the surface of the wood is completely dry prior to applying stain. Trust me on this one, it is not worth ruining your hard work up to this point because you followed the directions on a can of 15-minute pre-stain conditioner, through no fault of your own.
Pre-stain wood conditioners are best utilized if you plan on using an oil-based stain, which some woods naturally repel.
Shellac Washcoat
Shellac washcoats basically accomplish a similar goal but in a completely different way from what pre-stain conditioners do. While pre-stain conditioners penetrate deep into the wood to loosen the fibers so an even coat of stain can be absorbed, shellac washcoats work to create an even finish by limiting the amount of stain to be absorbed and creating a thin barrier on the wood. They can be applied to wood prior to staining to seal any imperfections or prevent an uneven coat.
Shellac washcoats are quite simply stains or finishes diluted with a thinning agent. Applying a shellac washcoat prior to staining gives a more subdued and weathered look to the wood.
Polyurethane Washcoat
A polyurethane washcoat is simply an oil-based poly mixed with mineral spirits. Poly washcoats seal the pores in the same way shellac washcoats do in order to provide a surface that will soak the stain in evenly.
For those that are environmentally inclined (myself included), shellac is derived from an extract of Laccifer lacca, or lac bug, while polyurethane is a synthetically produced product, a consideration that may or may not hold weight in your decision of which product to use. Also of note, poly has a tendency to carry a slight yellow tinge if subject to UV rays found in sunlight. For inside furniture located near windows or outside furniture, I would advise staying away from poly washcoats and finishes.
Black Tea Stain
Interestingly enough, black tea can be used as a stain accepting agent on wood or as a stain itself! Wood treated with black tea stain absorbs the subsequent stain much quicker compared to untreated wood. This typically leads to a darker finish when all is said and done. To combat this, apply the black tea stain with a cloth as previously discussed and immediately wipe the surface of the wood with a clean cloth to keep any excess tea stain from building up.
I highly recommend testing this process on a scrap piece of similar wood prior to applying it to your project. For those that are environmentally inclined, experiment with different combinations of black tea stain and various brews of coffee for a more natural look than what can be purchased in stores. Freshly ground coffee works best to give a color that more closely resembles the color of the coffee bean.
Simply steep tea in a container of water, using more tea bags the darker you want the stain to be. Apply with a rag and wipe clean. For coffee, grind coffee beans and mix with water. Allow the mix to sit for 15 minutes before straining the coffee grounds out. Apply with a rag and wipe clean.
Mineral Spirits
Mineral spirits are a petroleum-based thinning agent commonly used in painting and paint cleanup. Mineral spirits are a common ingredient in most pre-stain wood conditioners, yet not many have ever heard of them let alone used them to pretreat wood.
Wiping the wood down with a cloth soaked in mineral spirits simultaneously cleans the surface and prepares the pores and fibers to accept subsequent stain. They are much more cost effective than pre-stain wood conditioners and some woodworkers actually prefer the finish.
A technique for applying mineral spirits that I personally use but haven’t seen done elsewhere is to mix one part stain with two parts mineral spirits. Apply the mixture the same way as you would with a pre-stain conditioner but wipe dry immediately after applying. Let the wood set overnight before applying a full coat of stain. The end result is a beautiful two-toned stain that highlights the natural imperfections of wood.
Conclusion
As with any project, success often comes down to the right knowledge, information, and planning. Make the decisions on what stains, conditioners, finishes, and clear coats to use prior to starting the project as some might not be available at your local hardware store. Done right, a new coat of stain will transform any piece of furniture in your home and give you an updated look to enjoy for years to come!
Associated Questions and Answers
Do I Need to Prepare the Wood the Same Way if I’m Painting Instead of Staining?
The short answer is no, but to a certain degree. As was covered earlier, the goal when sanding wood to be painted is to create a rough surface for the paint to adhere to, which is very different from the process of preparing wood for stain. When preparing wood for paint, simply sand with 100 to 120-grit sandpaper for two passes and wipe clean with a moist cloth.
The best paint to use is a paint-primer mix, which bonds to sanded wood perfectly. For wood that shows visual imperfections or that needs wood filler or spackle prior to painting, it is best to first apply one to two coats of primer before painting.
Also consider what final look you wish to accomplish as the more coats of primer and/or paint you apply, the more hidden the imperfections and grain of the wood becomes. For example, if you want to keep the look of the wood, one coat of paint-primer will suffice. If going for a cleaner look, apply wood filler or spackle prior to sanding and two coats of primer before painting.
Do I Have to Apply a Clear Coat After Staining Wood?
The short answer is a resounding yes. Because stain penetrates the wood without creating a protective topcoat, as a finish like paint would, a protective barrier in the form of a sealant is required to withstand the day-to-day beatings furniture takes.
The most common clear finishes are lacquer and polyurethane sealants. Lacquer works in a way similar to stain in that it penetrates the wood and seals the fibers, while poly coats the surface in a protective film.
Lacquer dries faster, doesn’t require sanding between protective coats and can be applied with a pressure sprayer or from a can whereas poly is more durable and provides a thick protective barrier. Ultimately, the decision of which clear coat to use in your projects is up to you, but one should be used every time.
What Do I Do if I Don’t Like the Stain?
If you are not happy with the stain after it is dried, or if there are visible uneven areas of the wood, simply sand the piece with a medium-grit sandpaper and start again (unless you simply want a darker stain, in which case you can simply stain over it). Because of the previous preparations with pre-stain conditioning, the stain will not have penetrated very deep into the wood, meaning it won’t require much sanding to strip the wood back down to “new wood.”
After as little as two trips with a medium-grit sandpaper, shift to a fine-grit, apply another coat of conditioning agent, and give it another shot with the stain!
Does the Type of Wood Affect the Grit of Sandpaper I Should Use?
If you ask a professional woodworker, they will tell you that it does, but from my experience you can’t go wrong sticking to a 100 to 120-grit sandpaper for the first two passes and then a fine-grit sandpaper for two passes.
Although you can strip the wood down after applying a sealant like lacquer or polyurethane, it is a much easier process if you only have to strip down stain, particularly in the case of poly. For that reason, give your project a solid inspection prior to applying the sealant. It could save you valuable time in the long run.
How Many Coats of Stain Should I Apply?
Two coats of stain will give you project the best finish. Apply one coat and immediately wipe dry. Let the project sit for a minimum of 2 hours, preferably up to 24 hours. A good middle ground is to allow the project to sit overnight between coats of stain. Apply the second coat of stain, wipe dry, and let sit again. It is not necessary to sand the project between coats of stain as it would be for painted projects.
Can You Apply A Darker Without Sanding?
Yes, you can! As long as the first stain is completely dry, simply reapply a darker stain over the existing stain. Sanding is only required if you subsequently applied a clear coat. That said, my personal technique is to bring the wood back to “new wood” and starting fresh in order to get the exact color you are looking for.
When is the Best Time to Apply Wood Filler?
Wood filler can be applied prior to any step in the process, just remember that you will need one more sanding session to provide a smooth surface prior to staining. Also consider if wood filler is required to begin with. Wood filler is great for pieces that will be painted, where it will be hidden more fully. One of the biggest contributing factors to choosing to stain as opposed to paint is being able to see all the imperfections, grains, and inclusions in a piece of natural wood.