Bethlehem STACKS: the modular two-stage surface-mix bench torch

The Bethlehem STACKS is a two-stage surface-mix bench burner built to fill the gap between the Alpha and the Bravo. Its defining trait is modularity: it’s sold as a Top Mount and a Bottom Mount that can be bought in stages, so you can start small and add heat later. Like the rest of the line, it runs a quiet surface-mix flame and plays well with oxygen concentrators.

What the surface-mix flame gives you

The STACKS is surface-mix: fuel and oxygen meet at the face of the torch rather than premixing inside it, for the quiet, calm, low-backfire flame Bethlehem is known for. For the background on why that design is prized, see surface mix vs premix torches.

A torch you can build in stages

The two sections are designed to be bought separately and combined:

• STACKS I (Top Mount): a 6-jet sharp-flame fire on a 0.375in face. At full flame it draws roughly 2 LPM gas and 10 LPM oxygen — a small, focused flame for detail.
• STACKS II (Bottom Mount): an 18-jet fire with 48 oxygen ports on a 1in face. At full flame it draws roughly 4 LPM gas and 20 LPM oxygen — the broader soaking flame.

Run together, you get a two-stage burner that spans fine detail to medium soaking heat; bought one at a time, you can grow into it as your work and oxygen supply expand.

Glass, fuel, and oxygen

The STACKS handles beads, soft glass, and small boro and burns propane or natural gas with oxygen. Bethlehem notes it works well with oxygen concentrators, which fits its place in the line — but be realistic about scale: the bottom fire wants around 20 LPM at full flame, more than a single small concentrator delivers, so size your oxygen to the flame you actually run. See how many LPM does my torch need and oxygen concentrator vs tanks.

The hardware advantage

Like the rest of the line, the STACKS carries Bethlehem’s signature swivel and rack-and-pinion adjustment, so you can set a precise, repeatable angle and height — a real comfort over long sessions.

Where it sits in the Bethlehem lineup

The STACKS is the bridge between the entry Alpha and Star and the two-stage Bravo and Champion. Its build-in-stages design makes it a flexible on-ramp for someone who wants to grow within the brand. Compare the surrounding tiers in Alpha vs Bravo vs Champion.

Before you buy

Budget for the whole system, not just the torch: oxygen (a concentrator or tanks), the correct propane or natural-gas regulator, flashback arrestors on both lines, didymium eyewear, and ventilation. New to plumbing a torch? Start with the fittings, hoses & connectors guide and the glass torch safety setup guide.

Editor’s note: flame and flow figures above reflect Bethlehem’s own catalog for the STACKS sections. Bethlehem doesn’t publish current pricing, so confirm that — and how the staged sections are configured for your work — with Bethlehem before purchasing.