Step Tansu - Canadian Woodworking Magazine

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Step Tansu



Illustrations by Mike Del Rizzo

The step tansu became popular during the early Edo period in Japan, in the 1600s, when livable space was at a premium. Japanese for 'trunk' or 'chest', tansus ranged from small three step units to larger five and eight step units. The large step tansu fit into the architecture of a house serving two functions at once – easy storage for blankets and large household items, and easy access to the loft above. Traditionally, the height of a step tansu was directly proportional to the height of the second floor.

Japanese homeowners were taxed according to the livable area in their home. In order to save a little money come tax time, owners often relocated their large step tansu away from the loft. No access to a loft meant the loft was not livable, therefore untaxed. Those truly dedicated to tricking the tax-man, would construct their step tansu in two halves – an upper and a lower, and fasten the top half of the tansu with a hinge near the middle step, folding the upper portion into the lower portion creating a square cabinet, avoiding all suspicion.

I designed this tansu for beauty and storage, not for evading Revenue Canada or accessing a second story. To use your own tansu to the fullest I recommend incorporating a solid, one piece riser as opposed to the risers featured here.

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Design
Most western furniture finds beauty in symmetry. I was drawn to the general design of a step tansu because of the balance it achieves in asymmetry. A step tansu is able to divide a room or invite you into a room, directing your eye to it and then towards another aspect of the room that holds it, such as the sitting area beside its steps, or a piece of art above its peak. This tansu has the potential to really become part of a room’s personality, a rarity in much of today’s furniture design. Also, our modern urban landscape requires space saving solutions; the tansu maximizes storage space at the bottom, providing more open wall space for art, and, not surprisingly, can be customized to fit perfectly under a loft stairway.

I began Equinox Interiors as an outlet to create fine furniture incorporating a multitude of materials from the natural world. Japanese furniture design focuses on simple lines with minimal ornamentation and involves the use of natural materials – wood, paper, reeds, stone or metal. My tansu design feels light because of the paper and kumikos (creating the grill-like design), even though the finish is quite rich and bold. By using traditional Japanese materials in a non-traditional context, I’ve created something truly contemporary.


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Materials
One of Japan’s most highly sought after species of wood is zelkova, a ring-porous wood with a distinctive grain pattern, very similar to our common oak and ash species. Wanting to ground the design in Japanese tradition, and stay true to my Western roots, I chose to use solid white ash for the entire piece (short of the back and drawer boxes).

The paper I used is called Tokuatsu, hand-made in Japan and available in Toronto and Montreal at The Japanese Paper Place. Drastically different from thin Western paper, Japanese hand-made paper is world renowned for its amazing texture and versatility. Because wood fibers are woven together, the paper has strength similar to cloth.


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Construction
I machined the large end frame, five identical risers and five (almost) identical treads first. The length of the front and back rails for each of the five treads varies, decreasing as the treads ascend, requiring shorter front and back rails to connect to the end frame.

The end frame is typical frame and panel construction, but the risers are a bit different. The frames for the risers are machined the same way as the end frame, but in place of the panels are wooden kumikos. These horizontal and vertical wooden members join each other with a lap joint. A notch is machined into the frame to accept each kumiko. The horizontal kumikos are ⅜" x ⅜", while the vertical kumikos are ⅜" wide but only 3/16" deep. Since the vertical members are half the thickness, I cut lap joints in the horizontal members only – simplified construction and the addition of an interesting visual element.

With the risers assembled, I machined a ⅛" x ⅛" rabbet on the top, inside corner of each riser to offer a seat for the tread to sit in. Since the treads and risers are ⅞" thick, this left a ¾" x ¾" gap. I routered a partial bullnose on the end of a ⅞" x ¾" strip of ash to glue in the gap for added strength, producing a ⅛" overhang.

The front and back tread rails extend to the end frame and are secured there with a double dowel joint, the exception being the 2nd lowest tread. It is joined to the underside of the riser above it and is glued in place.

There are two rails extending from the bottom of the lowest riser to the bottom of the end frame. These add strength and allow a surface to attach the face frame and drawer slides. Both front and back rails are joined with dowel joints.

A solid bottom is required for the center cupboard and the secret compartment. These bottoms fit into the existing grooves machined in the sides of the front and back tread rails. A tenon must be machined on the edges of the bottoms to fit into the grooves.


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Once all the machining is complete to this stage, I dry fit every piece. To dry fit this piece by myself was difficult, but not as tricky as gluing, assembling and clamping the tansu alone! It is possible to do this by oneself, with some planning, but a second pair of hands makes assembly much easier.

Once the glue has dried, I carefully laid it on its back and started machining the face frame. To streamline the process some planning was required. I decided where I wanted to use mitre and butt joints well before I began this stage - the outside corners are miter joints and the inside joints are butted. The butt joints were strengthened with dowels. The 1¾" wide face frame can be glued in place as you cut it. Before gluing the top piece of face frame into place, I machined a groove to accept a strip of wood. This 3/16" thick strip secures the upper portion of the secret compartment.

The frame now machined and assembled, I take the dimensions for the two doors. I like to machine and assemble the doors so they just barely fit into the space then trim the doors according to the specific size and angle requirements. This takes a bit longer to do but the result is doors that fit perfectly. I also machined and installed an interior side frame on the left side of the centre cupboard to divide this area from the small drawer.

The mitred door construction is very similar to most doors, the two differences being the rabbet cut on the inside edge and the notches to receive the kumikos. The rabbets and kumikos are necessary for securing the paper. I had to keep the risers in mind while machining notches for the kumikos on the doors, wanting their proportions to be similar.
I attached the hardwood drawer slides and constructed drawer boxes to match. The slides are 1¼" x 1¼" solid with a ½" rabbet to accept the drawer. I use wooden slides because they are long lasting and when well built, provide years of smooth and easy use. Solid ash slab drawer fronts are machined and attached to the drawer boxes.

At the bottom of the secret compartment, ash cleats are placed on either side of the opening directly behind the face frame. Rare-earth magnets with steel cups and washers - (from Lee Valley), are fastened to the wood cleats to secure the small panel. A ⅜" hole accepts the dowel used to open the secret compartment panel. It is accessed from the open drawer below. A bit of pressure on the dowel overcomes the strength of the magnets, and the secret is unveiled.


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Secret compartment detail
Finishing
I sanded the entire piece with 150 grit paper. Sanding to a higher grit, however standard, would not allow the deep stain and glaze penetration that I was looking for. My first application was a mixture of Brilliant Crimson and Brown Mahogany aniline water stain (both available from Lee Valley), giving the tansu its red tones. I experimented with proportions and strengths beforehand. A wet coat was applied followed by a light sanding to remove any raised grain.

A coat of dark brown glaze was applied next, allowed to dry slightly, and then wiped off. The glaze tends to be left behind in the corners as well as in the pores of the ash, adding depth and character to the finish. In the interior of the tansu I applied a coat of dark reddish brown pigment. Once everything was dry, I brushed on four coats of satin varnish, sanding between coats. Varnish dries more slowly than other finishes, but provides a very durable finish that lasts for years.

Final Touches
Working with the hand made Japanese paper is not as difficult as might first seem. The Japanese Paper Place offers literally thousands of styles, colours and weights of beautiful paper and the rice glue required to adhere the paper to the frames. I cut the pieces of paper to the appropriate size, applied rice glue to the frame and kumikos then put the paper in place. Rice glue is water soluble, and easy to work with. Once the glue has completely dried I lightly sprayed the paper with water. At first this makes the paper swell and distort – without fail, causing my stomach to jump each time! After about 15 minutes the paper starts to contract, becoming taught on the frame.

Finally, I applied a furniture paste wax to the drawer slides to allow for easy movement, and fit the tansu with hardware.


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ROB BROWN
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Equinox Interiors