Monthly Archives: October 2010

Finishing for Non-Finishers, Part III


Preparing Surfaces for Finishing

Hand Work Requires Thought

Let’s get down to some basic facts.  Lumber goes through a number of steps on the road to becoming a component in a piece of furniture.  Typically it is sawn, jointed and reduced in thickness.  Additional shaping operations might also be involved.  Each of these steps leaves a signature behind and those machine marks are not a decorative effect.  You really cannot leave them behind and later call them design features.  They all need to be removed.  How you accomplish that impacts how you finish, and what that finish looks like.  Woodworkers generally choose one of two options: cutting (hand planes, scrapers) or abrasion (sandpapers).  As a general rule, do as much of this work as you can after the joints are cut, but before gluing up.  It’s a whole lot easier, for example, to clean up the apron on a table or the rails on a chair before rather than after they’re glued into the legs.

Admitting my Bias

In the interest of full disclosure, I am mostly a hand-tool woodworker.  That is not to say that I don’t use power tools.  I use them whenever they make sense.  There are many times, though, when a hand tool does a  job faster, more safely, and give a better result.  So if the following comments lean a little in the direction of hand tools, you’ll know why.

A Case in Point: The Hand Plane

Students who have taken my classes know I hate sanding.  Detest it.  So I avoid sanding as often as possible.  There are a number of reasons I feel this way, but the one that relates most directly to finishing is that sanded wood and hand-planed (or scraped) wood looks different.  One surface has been abraded to make it smooth, and it looks hazy.  The other surface has been cut to make it smooth, and it looks clear.  If you don’t believe me, do the following demonstration for yourself.  Take a well-tuned hand plane with a sharp iron, and plane the surface of a piece of cherry or oak, or whatever hardwood you have on hand.  Plane it until the milling marks are gone and you have a nice smooth surface.  Now take a piece of sandpaper of the grit you would normally use last in a sanding progression.  Most woodworkers don’t (and shouldn’t) sand beyond P220 grit, so use that.  Sand half the board you just planed.  It will be smooth, for sure.  But look at the difference between the hand-planed surface and the sanded surface, and you will see what I mean.  Hold it up to a window on a bright day and look at the way light reflects off both surfaces.  There is a marked difference, and I think the hand-planed surface is more appealing.

However, using a hand plane forces you to understand wood grain.  Ignore that characteristic at your own peril when you approach the workpiece with a plane.   Plane in the wrong direction and you risk tearing out chunks of wood, adding untold hours to your project as you wonder how to repair the damage.  If you’re a hand tool user, wood grain plays a role in a lot of the decisions you make.  When you’re gluing up a panel for a table top, for example, you want the grain in each part of the top running the same way, or you must change the direction in which you plane.  And if you bookmatch a panel, you have introduced a grain reversal.  Nothing you can do about it, so think it through carefully.

In any event, a well-tuned hand plane with a sharp iron will make short work of marks left behind by saws, jointers and thickness planers.  They are most certainly worth the time and effort needed to learn to use them well.  As your skills and fussiness increase, you will find that scrapers can remove the little marks left by hand planes and yield a beautiful, smooth surface.

Sanding

Sanding will get rid of the machine marks, although it will be slower, noisier and much dustier.   There are some woods that are really difficult to plane; any species with interlocked grain falls in this group.  So plan extra time, make sure you wear hearing and eye protection and carefully plan a way to keep all that dust out of your lungs.  And while you’re at it, plan some extra time to clean up the dust from your shop before you start finishing, so the little dust nibs don’t fall out of the air onto your nicely sanded and now-wet-with-finish tabletop.

If I am forced to do a lot of sanding, I allow extra time in the schedule to account for dust.  Initially I try to minimize as much dust as I can by using vacuum attachments for power sanders, and by constantly vacuuming the surface as I finish hand-sanding.  Typically I will sand one day, allow another day for dust to settle out of the air, and vacuum my finishing area on the third day.  Finishing begins the day after.

As a rule of thumb, P220 is as far up the grit progression as you need to go on the bare wood.  As long as you have done a good job and were careful not to skip grits (remember that sandpapers are a system, and they are designed to work sequentially) going beyond P220 is a waste of time.  I strongly suggest that the final sanding step be done by hand rather than machine.  Sand with the grain, and sand carefully. Your objective is to ensure you haven’t left behind any of those little “pig-tails” that are the telltale of a random-orbit sander.

A Final Inspection

Before you put away the sander, the scraper or the hand planes, wipe down your project with denatured alcohol or naphtha.  Use the brief time before the solvent evaporates to carefully examine the surface for imperfections.  I like to use a bright light to help with this inspection, either a double halogen work light on a stand, or the sun through a window.  The light should come from in front of you, bounce off the work and then reflect into your eyes at a very shallow angle.  This is your last chance to catch a bit of tear-out, some glue that you missed, or any other blemish that will be magnified by finishing and top-coating.

Remember Those Cut-Offs?

If you saved cut-offs from the project, treat them the same way you are treating actual project components.  If you are sanding, sand the cut-offs with the same grits in the same progression.  If you are hand-planing, or scraping, do the same to your remnants.  This step is important, so don’t skip it.  While you’re at it, start making notes about what you are doing, and write them on the cutoff – on the side opposite the one you’re planing, scraping or sanding.  You will add to these notes later, so leave room to document additional steps.

In the next post we’ll talk about the assembly process and the final preparations for applying a finish.

Finishing for Non-Finishers, Part I
Finishing for Non-Finishers, Part II

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Jeff Zens owns and operates Custom Built Furniture in Salem, Oregon. He is a frequent woodworking instructor and writer.

Categories: Woodworking | Tags: , , , , | Leave a comment

Finishing for Non-Finishers, Part II


It’s a Continuous Process

In the first post in this series I suggested that finishing starts at the beginning of the project.  I’ll expand on that concept in this post, suggesting that finishing is really a continuous process that extends throughout design and construction.

In a very real sense, one of the first considerations a woodworker gives to a project is the finish.  You’ll ask yourself questions early on in the project like “Where will this piece eventually live?”  “Am I trying to match the appearance of existing furniture or have the piece make a bold statement of its own?”  “Am I going to paint this piece, or let the color and graphics of the wood make their own contribution to the overall effect?”

The answers to these questions will, to a large degree, drive your stock selection.  If you plan to paint the wood, you might select birch, or poplar, or some other “paint-grade” stock.   If you are trying to match an existing decor, you most likely will look for stock of the same (or similar) species.  If you want the piece to make a bold statement in a room full of cherry or walnut, you might prefer the contrast maple would offer.  In the first case, you will probably obscure the figure of the wood with your paint.  In the latter two examples you will most likely want that figure to be seen and admired.  In all cases, though, how you treat the wood during the rest of the design and construction process will either complicate your life or make it somewhat less stressful.  So your consideration of the finish really should begin at the beginning.

Save your Off-Cuts

I will mention here some excellent advice I received a long time ago, and which I have repeated often on various blogs and in classes.  No matter what finish you plan to use, save pieces of the project stock for later use as finishing samples.  This advice is particularly true for stock that makes up what I will refer to as the “show surface”.  Generally, “show surface” means the part of the furniture that will get the most attention, either visually or tacitly.  In a table, the show surface would logically be the top.  For a chest of drawers, you would be concerned with the top, and perhaps also the drawer fronts or one of the sides of the chest.  What a piece of furniture looks like is half the battle.  What it feels like is the other half, and unless your creations go directly from the shop to the Smithsonian, people will touch what you make.  I’ll discuss this concept more in a later post.  For now, just remember to save pieces of this stock.  Pieces six to eight inches wide and eighteen to twenty-four inches in length are ideal.  Again, more about this in a later post.

Care During Assembly

You’ll find a ton of advice in woodworking magazines about careful techniques.  There are two or three that I want to repeat, and at least one that I haven’t read elsewhere, but that I observe in my own shop.

Control Glue Squeeze-Out

Glue is your friend, right?  Well, sure, it helps to hold a joint together, but that’s as far as it goes.  Either it dries too quickly (always during a glue-up) or not at all (when you want to move ahead with the project).  Glue is NOT a friend to the finisher.  So you must learn to control it.

I’m not going to repeat all of the tips and tricks that have been written about elsewhere telling you how and where to apply glue in a joint.  What I will say is that you need to keep the glue IN the joint, and OFF the surfaces of wood that will be finished.  However, no matter how careful you are, some glue is going to get where you don’t want it.

Glue gets to the outside of a project in a couple ways.  It either squeezes out from a joint, it drips from somewhere else, or we spread it around with our hands.

Gravity can help or hurt

When you glue up a panel – a table top or something similar – set the glue-up off to the side with the glue seam perpendicular to the floor.  That way all the squeeze-out will stay localized to the joint.  The squeeze-out will run down the joint toward the floor.  Placing the glue joint parallel to the floor invites the squeeze-out to run down both faces of the panel as gravity does its job.  Use this same technique to your advantage when you glue up  other joints.  The idea is to keep the glue localized, and prevent its movement on the exterior surfaces of the project.

Getting Rid of Squeeze-Out

When glue squeezes out, my advice is to just leave it alone.  I don’t agree with the technique that a damp rag will take care of wet glue.  Glue and water are sometimes mixed together to create what is known as “glue sizing” which is frequently used as a stain controller.  In other words, it slows down or stops the penetration of finish into the surface of the wood.  Why create that situation unintentionally?  Instead, set the glue-up aside, and monitor the glue as it dries.  Wait until it gets to a rubbery condition, and then use a putty knife or a paint scraper to remove it.  Don’t be tempted to do this too quickly; glue skins over fairly rapidly, and what might look like solid rubbery balls of glue can conceal liquid glue in their cores.  If you start scraping too soon you’ll just break open these little glue bottles which will then spew their contents all over your project.  Let them dry, but don’t let them harden.  You’ll be pleasantly surprised at how easy it can be to remove glue in this condition.  Letting glue dry overnight just makes your job more difficult.

Keep Your Hands Clean

When furniture maker Phil Lowe glues up a table top, he uses a Mark-I glue spreader.  Before you run off to Google, I should explain that a Mark-I glue spreader is more commonly referred to as a right index finger.  The Mark-I has a number of advantages.  Primary among these is availability, presuming you have managed to keep it attached to your hand.  The Mark-I is also quite effective.  These qualities should encourage you to use push sticks.

There is a drawback, though.  Glue on the fingers ends up being glue on the project, unless you are really careful.  If I’m using my own Mark-I, I keep a wet towel on my work table, and I carefully wipe glue from my hands before touching the work.  A second option is to use a small scrap of wood as a glue spreader.  This technique might be a little slower than the Mark-I, but you pick up the time not having to clean your hands.  I decide which technique to use based on how complicated the glue-up is.  If it is a panel, the Mark-I is my first choice.  If it’s dovetails or mortise-and-tenon, I use a stick, an accordion bottle, or some other precise way of getting the glue only where I want it.

With practice, you’ll figure out how much glue is the right amount.  You do want to see a bit of glue coming out of a panel glue-up, but you don’t want to see anything outside the mortise-and-tenon joint.  In the final analysis, controlling glue is a matter of experience gained through practice.  From the perspective of the finisher, the less glue on the show surfaces, the better – but what does squeeze out must all be removed before you start applying a finish.

In the next post I’ll get into the subject of hand- vs. power tools, and how those decisions and techniques affect your finish, and continue with the discussion of care during assembly.

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Jeff Zens owns and operates Custom Built Furniture in Salem, Oregon. He is a frequent woodworking instructor and writer.

Categories: Woodworking | Tags: , , , , | Leave a comment

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