Curved Plywood Buying Guide: RF Bending vs. Cold Press vs. Steam Bending

Curved wood parts get made four or five different ways, and the quotes you get back will vary wildly depending on which shop you happened to call. That is not usually because one shop is gouging you. It is because a chair shell and a curved reception-desk front and a run of twelve radius cabinet doors are three genuinely different jobs, and the press that is right for one is wrong for the others.

This is a plain walk through the processes, what each is actually good at, and the handful of things about your part that decide the answer.

RF bending (radio frequency)

Also called high-frequency or dielectric bending. A glued plywood layup goes into a matched male/female form, and a radio-frequency field excites the water molecules in the adhesive and the veneer. The heat is generated throughout the full thickness of the part at once rather than conducted in from a hot platen, so the glue line cures from the inside out while the part is held at shape.

What it is good at: tight, repeatable radii with very little springback. Cure times in minutes rather than hours, which is what makes production quantities realistic. Consistency part to part — the hundredth shell matches the first. Most commercially produced molded plywood seating is made this way.

Where it costs you: tooling. A form has to exist before the first part comes off the press, and on a new part that is usually the first real number you will be quoted. Very small runs struggle to absorb it.

Cold press

No heat at all. The layup is clamped into the form and sits there until the adhesive cures on its own, often overnight.

What it is good at: low tooling and setup cost. For a handful of parts, a prototype, or a one-off architectural piece, cold press is frequently the honest answer, and anyone telling you otherwise is selling you press time you do not need.

Where it costs you: throughput. Each cycle occupies the form for hours, so the form becomes the bottleneck the moment quantity rises. Gentler radii are the practical limit, and springback is more of a factor than with a heat-cured process.

Steam bending

A different animal entirely. Solid stock — not plywood — is plasticized with steam and bent over a form.

What it is good at: solid-wood rail, frame and hoop work, where you want continuous grain wrapping the curve. Chair backs in the Thonet tradition, curved handrails, boat parts.

Where it costs you: it is not a plywood process and cannot produce a laminated panel. Expect more springback, more variation part to part, and a higher reject rate. Species matters enormously — white oak and ash bend, others fight you.

Induction and hot platen pressing

Heat conducted into the layup from the platen surfaces.

What it is good at: larger, flatter formed panels, and exposed-grade faces where surface quality is the priority.

Where it costs you: time to bring the core of a thick layup up to temperature. The thicker the part, the more the advantage swings back toward RF.

The five things that actually decide it

1. Radius. The tightest radius anywhere on the part, not the average. This is the single biggest constraint and it interacts with thickness — a radius that is routine at 1/4" may be impossible at 3/4".
2. Thickness and ply count. More, thinner plies bend tighter than fewer, thicker ones at the same finished thickness. Thickness drives stiffness and cost together.
3. Quantity and release schedule. A one-time run of 50 and a blanket order of 5,000 a year are priced differently and often belong at different shops. Tooling amortization is why.
4. Face grade. Whether the face is exposed in the finished product, painted, or a substrate under laminate. This changes the veneer you need and a meaningful share of the price.
5. Compound curvature. Bending on one axis is routine. Bending on two — a true compound curve, a saddle, a dished shell — is a different conversation, different tooling, and sometimes a different process.

A rough rule of thumb

• Tight radius, production quantity, laminated panel — RF bending
• Gentle radius, low quantity, prototype or one-off — cold press
• Solid wood, continuous grain around the curve — steam bending
• Large panel, exposed face, moderate curvature — induction or hot platen

Rules of thumb break, though, and they break most often on the parts people care most about. A large exposed-grade shell with a tight radius pulls in two directions at once. That is the kind of part worth a conversation rather than a form submission.

What to send when you ask for a quote

A dimensioned drawing gets you a real number fastest. If you do not have one, a sketch with the critical dimensions and a photo of a sample will usually do. Include the tightest radius, the finished thickness, the species and face grade, the quantity, and any secondary operations — trimming, CNC, boring, edge banding, sanding, finishing. Say whether tooling already exists.

The more of that you can answer up front, the fewer rounds of questions before you get a number you can actually use.

Where Supply Tie fits

We are a manufacturer's rep, not the press. What that buys you is a straight answer about which process and which shop your part belongs at, instead of a quote from whoever happens to own one machine. If your part really wants cold press, we will say so.

Send a drawing on the RF bent plywood page and we will come back with questions and a number.