Bent lamination is the quiet workhorse of curved woodworking. It needs no steam box, no bending iron, and no soaking tank. You make a form, glue several thin strips together, clamp them around the form, and wait for the glue to cure. The result is a laminated curve that can be planed, scraped, and finished much like solid wood.
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Why thin strips bend
A solid board resists bending because its outside face must stretch while its inside face compresses. The thicker the board, the greater the strain on those faces. Thin strips reduce that distance. When you bend a stack of unglued strips around a form, each strip follows the curve with far less resistance. Once the glue cures, the strips work as one piece. Because the grain of every strip runs lengthwise, the finished lamination does not have the crossbanded look of plywood; it reads as a single curved piece of wood.
Shape the form first
The form is the part of the job that most affects the finished curve. Draw the desired curve full size, then cut it from plywood or MDF. Two or three layers screwed together give a form wide enough for most furniture parts. The face that touches the strips must be smooth and fair. Sand away saw marks and check for dips or bumps. A flaw in the form will print itself into every lamination.
If you will make several identical parts, add an inner caul that matches the inside of the curve. This spreads clamping pressure and keeps individual clamps from leaving marks. For one-off work, a single male form plus a few simple cauls is enough.
Before applying glue, cover the contact surfaces with packing tape or plastic release sheet. Strips are coated in wet glue; without a release layer they can bond themselves to the form. Waxed paper works for one quick use, but it tends to wrinkle and stick.
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Prepare the laminae
Resaw straight-grained hardwood into strips, or buy veneer of the thickness you need. A thickness around 1/8 inch is a forgiving starting point for chair curves and lamp arms. For tighter curves, go thinner, down to 1/16 inch or less. Keep all strips in one lamination the same thickness. If one strip is thicker than the rest, it will take most of the clamp pressure and its thin neighbors may not get enough contact.
Cut the strips slightly longer and wider than the finished part. Discard strips with knots, checks, or pronounced runout. The outside of each bend should have clean, continuous grain, because that face carries the most stretching.
Make sure the surfaces are flat and freshly prepared. Planed or well-sanded strips glue more securely than burnished or glossy strips. If a strip is wavy, it may not lie tight against its neighbor, leaving a gap that appears only after the glue has dried.
Glue, clamp, and cure
For indoor furniture, a standard PVA woodworking glue is sufficient. For a window seat, bathroom piece, or outdoor item, use a waterproof-rated PVA or polyurethane glue. Polyurethane needs moisture to cure, so lightly dampen the wood and support the assembly firmly while it foams. Epoxy is a useful alternative when you need a longer open time, but it is messier to clean.
Spread the glue evenly on both faces of every strip. You want the surface wet, not flooded. A small roller or a wide brush works well. Assemble the stack before the glue skins over, and keep all clamps waiting.
- Lay release film on the form.
- Brush glue onto both faces of each strip and stack them in order.
- Cover the stack with release film, add cauls, and position the clamps.
- Tighten from the center of the curve outward.
- Stop when a thin, even bead of glue appears along the edges.
- Let the assembly cure undisturbed overnight.
Use a strap clamp around the form for the most even pressure. If you are using ordinary clamps, set cauls on both sides of the laminate so each clamp squeezes a wide area. Pull the clamps just until the glue bead forms. More pressure can starve the joint and actually weaken it.
Let the piece cure overnight in the clamp. A cold workshop extends the cure time, so if the glue manufacturer suggests a minimum time, add several hours. Do not release the clamps early to look at the curve. The only reliable inspection is after a full cure.
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Allow for spring-back
When the clamps come off, the lamination will relax a little. This is normal. It never springs all the way back to flat, but it will not match the form exactly. The fix is to overbend the form slightly, cutting the curve deeper than you need so the final part rests where you want it.
The amount of spring-back depends on the wood species, the number and thickness of the strips, and the radius of the curve. It cannot be predicted safely by eye. Before committing your good wood, make a test lamination with the same strips, glue, and radius. Measure the curve after it is released, then adjust the form by that amount. It is much easier to reshape a form from cheap plywood than to remake a piece from walnut.
Leave the finished lamination clamped a little longer than you think necessary if you can spare the clamps. After release, trim the ends, scrape away dry glue, and plane or sand the faces. The curve can be fitted like any solid part because the grain runs with its shape.
Mistakes that show up later
Most bent lamination faults appear after the clamps are off, so inspect each strip before it goes into the stack. One weak strip between good ones can open into a gap.
Do not let the glue skin over before the clamps are tight. Once it starts to set, the layers will not pull together evenly.
Do not use a form with a sudden corner. A sharp radius can split the outer face even in thin strips. Make the curve gentler or reduce the strip thickness.
Do not skip the release film. It seems like a small detail, but a form covered in dried glue is misery to clean.
Let the clamps do the work. Bent lamination does not require force or heat; it requires clean strips, an accurate form, even pressure, and time.