Category: The Anarchist’s Design Book

You can greatly increase the strength of a woodworking joint by “sizing the joint” or employing “glue size.” But what the heck do those terms mean? And how does the process work?

The word “size” as it relates to an adhesive is a synonym for “washcoat” – a thinned version of the adhesive you are using. “Sizing” with a glue has a long history in our language, and it is employed in a variety of ways – fine art painting, house painting, wallpaper and other mechanical arts.

Basically, to “size” a joint means to apply a thin, preliminary coat of glue to a surface.

Why would anyone do this in woodworking?

I know you’ve been told this a thousand times, but wood is like a bundle of straws. The end grain represents the open ends of the straws. So when you put a liquid on the end of a straw, what happens? It gets sucked into the straw. When you put a liquid on the outside of a straw what happens? If that liquid is glue, then the straws get bound together.

This straw-like property is why end-grain joints in wood are weak. The straws suck the glue away from the joint, starving it of adhesive.

But what if we could plug these straws so they couldn’t suck the glue away from the joint?

And that’s what “glue size” does. The thin coat gets sucked into the end grain. After a couple minutes it begins to set up, which plugs up the straws. Then you apply a full coat of glue, and it cannot be sucked away from the joint – thanks to the plugs. So the joint becomes stronger as a result.

I’ve been experimenting with glue size for more than a decade. At first I thinned glue with water to create my “size.” That seemed logical. It turned out to be unnecessary. Simply paint a thin coat of glue on the end grain and the process works perfectly. Yellow, white and brown glues are all about 40 percent water already and are easily sucked into end grain without any thinning.

After I paint on the “sizing coat,” I wait a minute or two (or longer). The end grain will become dry as it pulls the adhesive in. That’s when I apply a full coat of glue on the end grain and on all face-grain surfaces of the joint.

It takes only an additional minute or two to apply a sizing coat during assembly. In fact, it can add exactly zero time to a glue-up if you simply start by painting all the end-grain surfaces first. Then paint the face-grain surfaces. Then paint the end grain again.

Does it work? The scientists at Franklin International have studied sizing and compared the strength of joints with and without it. As far as I know, they haven’t published a technical paper on this topic. But in interviews they contend that sizing the joint significantly improves its strength. After 23 years of working with the technologists at Franklin, I can say one thing for sure: They’ve never lied to me or led me astray.

Bottom line: Doesn’t hurt. Might help.

— Christopher Schwarz

After the busiest Spring on record, I’ve managed to turn down the volume a bit in the workshop and return my focus to the new projects for “The Anarchist’s Design Book.” One of the projects I’m most excited about is a so-called Mule Chest.

I’ve always liked the format. It’s a chest with a couple drawers and it is incredibly easy to build with nails and rabbets. (Much easier than a traditional chest of drawers.) Mule chests look great in pine or an inexpensive hardwood. And they go together as quickly as a six-board chest.

In designing my version for “The Anarchist’s Design Book,” I wanted to retain its historical simplicity but bring the form into the present day. That meant reducing the ornamentation and adding some asymmetry.

It looks good on paper. And the mule’s skeleton is looking promising as well.

The good news is that if the design looks like crap, it will be easy to bang out another one with different proportions.

— Christopher Schwarz

 

It doesn’t matter if you’ve been woodworking every day for 23 years, failure will find you on a regular basis.

It doesn’t matter if you make a dozen drawings. Build a half-scale model. Remake the seat twice. Remake the legs twice. Or do a careful dry-fit.

All that is not enough.

Above is the latest failed prototype stool for the expanded edition of “The Anarchist’s Design Book.” Like my design for the armchair for this book, the stool design is fighting me every step of the way.

This design failed both mechanically and visually. Mechanical failure: The seat cracked a tad in two places during assembly. This is the result of the undercarriage being too complex for a small structure. All 20 mortises were drilled by eye (no drill press). And the combined slight imperfections stacked up to make the undercarriage difficult to assemble and slightly twisted. And if I have trouble assembling this stool, imagine the problems a new woodworker might have who has never built one.

Visually, the rung positions of the stool leave me flat. The lower rungs are positioned so both short people and tall people can use the stool comfortably. The different rung heights accommodate popliteal heights at different ends of the bell curve of people. And by that measure, the stool works quite well.

The top rungs were positioned so you could easily pick up the stool with one hand to move it around. That idea nearly worked. The problem is that the stool swings toward you when you pick it up and might bark your shins.

By focusing on those functional bits, I made myself a stool that’s a bit visually boring.

It’s not a total loss. We’ll use this stool at the storefront until the cracks in the seat get worse (they might not). Then we’ll use it to make a bonfire and roast some weenies.

Back to the drawing board. Luckily, I have about four more stool sketches to explore.

— Christopher Schwarz

P.S. Comments are disabled because I’ve beat myself up enough with this project and don’t need the help of the internet.

Whenever I can manage it, I try to build an experimental chair alongside one of my trusted designs. It gives me a chance to use less-than-perfect wood and see how things that have germinated in my sketchbook look in real life.

This week I started two stick armchairs in walnut – one that will be for sale and a second that might be for fire.

I’m building the experimental chair using the sappier parts of a walnut slab I bought in Lexington, Ky., last month. The board was cut from a street tree, so it’s not like lumberyard walnut. My tree grew fast, out in the open and has some odd coloring and grain, which is typical for a street tree.

The experiment with this chair is the armbow. With a traditional three-piece armbow, the “doubler” – the piece that joins the two arms – has always been a magnet for my eyes. I like the look – it’s traditional – but I’m always looking for ways to make the doubler recede into the overall design of the arm.

After chatting with Narayan Nayar about my efforts to minimize the doubler, he suggested repeating its design elsewhere on the chair. It could be added to the underside of the arm. Or the top of the chair seat. Repetition would make the doubler look more like part of a pattern than an “eye catcher.”

So after some sketching, I decided to use a “double doubler” that has 30° bevels on all edges – one on top of the arms and one on the bottom of the arms. I think I like the way it looks. But I’m going to have to finish the chair to know for sure.

Earlier Experiments
Some experiments work so well they get adopted immediately. A couple years ago I started making my stretchers into double-tapered octagons. Making this shape is a fair amount of work with a plane and a couple cradle blocks on my workbench.

But I loved the double-tapered octagons immediately.

Before embracing the double-taper octagon, I would turn or plane my stretchers into a round shape, usually cigar-ish or with a bulge in the middle. These rounded forms are traditional shapes, but I always thought they conflicted with the facets on the six- or eight-sided legs.

Other design ideas survive on the bench for minutes or even seconds before being chucked into the scrap pile. I try to forget about those ideas before I’m even tempted to write about them on the blog.

— Christopher Schwarz