Best Scientific Glassblowing Hand Torch: Premix Picks for Seals

Short answer: For scientific and lab glassblowing, where the work is seals, lathe joints, and concentrated heat on quartz or borosilicate, the torch you want is almost always a premix hand torch. Premix burners mix gas and oxygen inside the torch body and throw a hot, concentrated, higher-velocity flame that is well suited to making seals and heating small areas, which is exactly what bench and lathe work asks for. The catalog picks in this class are the National 3A-B and its siblings, the Nortel Unitorch family built specifically for lathe and seal work, the Carlisle Universal Hand Torch, and the Herbert Arnold Premix Hand Torch. Which one fits depends on your fuel, your tips, and how fine or how heavy your work runs.

If you are still mapping out the whole rig, start with the complete glass torch buyer’s guide. This article is the focused look at the hand torches scientific glassworkers actually reach for.

What scientific and lab glassblowing asks of a hand torch

Scientific glasswork is a different job from beadmaking or sculptural boro. The tasks are ring seals, graded seals, glass-to-metal seals, joining tubing on a lathe, closing round bottoms, sealing fritted discs and dewars, and flame cutting. A lot of that happens on borosilicate standard-wall tubing or on quartz, both of which demand a hot, tightly controlled flame that you can put exactly where the joint needs it and nowhere else.

That points to three requirements. First, a concentrated flame: a broad soft flame wastes heat and warps the area around a seal. Second, tip interchangeability, so one torch body can go from a fine needle for a small seal to a broader tip for preheating a larger piece. Third, quartz-capable heat, because quartz works far hotter than soda-lime glass and a torch that cannot deliver a hot, oxygen-rich flame will simply not move it.

Premix versus surface mix, and why seals favor premix

There are two ways a torch mixes its gases. A surface-mix torch keeps oxygen and fuel separate until they meet at or just past the face, giving a broader, softer, lower-velocity flame that is good for preheating large apparatus and shaping big tubing. A premix torch combines gas and oxygen inside a chamber in the body and produces a very concentrated flame. The Scientific Glassblowing Learning Center puts it plainly: premix is the preferred style for making seals and heating small, concentrated areas, and if a glassblower could keep only one torch, the premix is the one they recommend, largely because interchangeable tips let its flame character change across a broad range.

That is why this guide foregrounds premix hand torches. It is not that surface mix has no place in scientific work; large preheats and heavy tubing often go better on a soft surface-mix flame. It is that the defining scientific tasks, the seals, favor premix. For the full comparison, see surface mix versus premix torches.

The scientific premix hand torches in this guide

Every model below is a premix torch drawn from our catalog. Mix type, mount, fuel, and price come straight from the catalog record for each model, which tracks the maker’s own published specs.

Editor’s note: Prices are reference figures. The National figures are National’s 2024 list prices for the base torch, the Nortel figures are Nortel’s own US-dollar prices (converted from Canadian dollars, so they move with the exchange rate), the Carlisle figure is Carlisle’s starting price, and the two Arnold figures are our US estimates beside Arnold’s euro list (see the Arnold section). Confirm the current figure with the maker before you buy, since tips, hoses, and configuration options all add to the base price.

National 3A-B, 3B-B and 4B: one body, many tips

National’s premix hand torches are the workhorse of this category. The 3A-B is a current premix hand torch with a rotating leak-proof O-ring union, and National lists it for city, natural, mixed, propane, and butane fuel gases with either oxygen or compressed air. The key thing to understand is that flame size and oxygen use depend on the installed tip. There is no single flow figure for a 3-series National, because the tip you screw on decides the flame. That is a feature for lab work, not a gap: you keep a set of tips and change the flame to the task.

The 3B-B is the same torch with one difference National states outright: it adds 9/16-18 B-size threaded hose fittings. Choose between the two on your hose hardware, not on flame performance, since the flame is identical.

The 4B is the industrial model. It ships with a 1/4-inch NPT by 7-inch elbow and B-size hose connections, and it uses N-4, N-6A and P-Series tips. National markets it as an industrial torch rather than the bead-oriented 3-series, so it is the one to look at if your work runs heavier or you want the industrial tip range. In the catalog it is a boro-focused torch.

The one bench member of this group is the 6B, a stand-mounted version of the 3A-B with the same flame, sold without tips. It is the exception in a list of hand torches: same premix flame, mounted rather than held. If most of your lab work is at a fixed station, the 6B gives you the 3A-B flame without holding the torch.

Editor’s note: Our catalog lists the National 3A-B, 3B-B, and 6B as running both soft and borosilicate glass, which follows National’s own fuel and use notes. In scientific and lab practice, though, premix hand torches are aimed squarely at boro and quartz, and community sources report that premix hand torches do not handle soft soda-lime (Moretti or Effetre) as gracefully as a forgiving surface-mix bench torch. If soft glass is your main material, weigh that before you buy on the scientific-torch strength alone.

Nortel Unitorch 6, 9 and 12: the dedicated lathe and seal hand torch

The Unitorch is the torch in this guide built for exactly this work. Nortel’s own listing puts it on lathe work, dewars, fritted discs, round bottoms, ring seals, graded seals, glass-to-metal seals, and flame cutting, and says it works 40 mm quartz or 75 mm borosilicate standard-wall tubing. The base model carries six stainless-steel tips. This is a scientific and lathe hand torch for intermediate to advanced work on boro and quartz, not a beginner soft-glass torch, and it should never be read as one.

The family scales up. The Unitorch-9 adds a nine-tip head at roughly 20 inches long, which lets the operator stand back from an intense, narrow band of fire. The Unitorch-12 carries twelve stainless tips on a stainless manifold at about 2 lb, for the most fire in the family. All three run the same scientific task list; the tip count and length change how much concentrated heat you can put on a joint and how far your hand sits from it. For clamping one to a lathe or a fixed station, see the best lathe torch guide.

Editor’s note: Some dealer listings add hydrogen to the Unitorch’s fuel options. Nortel’s own product page lists only propane and natural gas, so those are the fuels we record. Nortel’s pages list hydrogen on none of its torches. If you need a hydrogen flame for quartz, confirm the configuration with Nortel directly rather than relying on a third-party listing.

Nortel Twin Fuel Handtorch: single-point premix for quartz and lathe boosting

The Twin Fuel Handtorch is Nortel’s single-point premix hand torch: an injector-type mixer with one-hand finger control on a lightweight aluminum handle, 16 inches long. It takes multi-orifice, ribbon and National-style tips, so a shop already running National tips can add it without a new tip set. Nortel aims it at quartz and high-temperature work, lathe work and boosting the fires under a lathe. Despite the name, Nortel’s pages name no fuels for it; Nortel’s torch index says its torches run natural gas or propane with oxygen. At $172 it is the least expensive Nortel here, though the National 3A-B and the Carlisle Universal start lower. The Arnold Premix vs Twin Fuel comparison goes model to model against Arnold’s sealing torch. For the same maker’s other hand torch, see Red Max Handtorch vs Twin Fuel.

Carlisle Universal Hand Torch: interchangeable nozzles and carburetors

The Carlisle Universal Hand Torch is a premix torch that mixes gases inside the body through a carburetor unit. It runs natural gas, propane, or hydrogen with air or oxygen, and it is offered with an interchangeable 1/4-inch or 3/8-inch nozzle. Carlisle pairs each nozzle with its own carburetor: the 1/4-inch nozzle uses the #74 carburetor, the 3/8-inch nozzle uses the #34. The body is brass with chrome plating. Beyond the standard torch, Carlisle also lists Shorty, High-Capacity, and Unecon configurations, so the Universal is really a small family you can spec to the work. It is the value pick among the purpose-built shop hand torches here; Universal vs Arnold Mini sets it against Arnold’s fine-needle torch.

Herbert Arnold Mini and Premix hand torches: fine-needle precision

Herbert Arnold builds the precision end of this category, and both of its hand torches here are premix by Arnold’s own word (Mischgassystem). Each comes in propane (PS), natural gas (ES) and hydrogen (WS) versions, and a given torch runs the fuel it was built for.

The Mini Hand Torch (126/20) is Arnold’s torch for the smallest glass and quartz instruments, with a fine needle flame. It ships with two curved copper jets with stainless inserts, 0.5 and 0.8 mm bore (0.3 and 0.5 mm on the hydrogen version), and Arnold sells replacement jets from 0.3 mm, stainless jewel-insert jets down to 0.18 mm, a two-jet distributor and a stand. Arnold publishes no pressures or gas consumption for it. If your work is the smallest seals and finest detail on quartz, this is the tool built for it; the best torch for quartz guide covers the fuel side of quartz work.

The Premix Hand Torch (126/22) is the larger sibling and the one Arnold rates as a sealing burner. Gas and oxygen each have a fine needle valve, and the upper part comes off with a union nut for interchangeable jets: three stainless jets of 0.8, 1.0 and 1.3 mm come with it (groove jets on propane and natural gas, single-hole jets on hydrogen), and two- and four-jet distributors are sold separately. Its smallest jet is the Mini’s largest supplied jet, so the two cover adjoining ranges rather than the same flame. Unusually for this class, Arnold publishes its figures: on propane, 50 mbar gas (about 0.7 psi) and 0.5 to 1.5 bar oxygen (about 7 to 22 psi), with a maximum oxygen draw of ~2.8 LPM.

Editor’s note: Arnold’s 02/2025 price list gives EUR 304 for the Mini in every version, and EUR 400 for the Premix on propane or natural gas (EUR 378 on hydrogen), excluding VAT; the dollar figures in the table are US reference prices. The psi values are our conversions. Confirm the version and current price with Herbert Arnold before buying.

Fuel, oxygen and pressure: what to confirm with the maker before you buy

Because these are premix torches, the details that decide whether a torch fits your bench live in the maker’s manual, not in a general guide. A few points to settle before you commit:

• Tips decide the flame. For the National 3-series and 4B, and for the Nortel and Herbert Arnold torches, the tip or jet you install sets the flame size and oxygen appetite. Plan your tip set with the torch, and expect no single flow figure to describe the whole torch; the one published maximum here, Arnold’s for the Premix Hand Torch, is a ceiling at its largest flame.
• Fuel gas. Confirm the torch runs your fuel. The National torches list propane, natural gas, and butane; Nortel and Carlisle list propane and natural gas (Carlisle’s Universal also lists hydrogen); the Herbert Arnold hand torches come in separate propane, natural gas and hydrogen versions, so order the one built for your supply.
• Oxygen versus compressed air. Some of these torches accept compressed air as well as oxygen. Quartz and hot boro seals generally want oxygen; confirm what your work needs against what the torch and tip support. If air is genuinely on your list, sizing a compressor and keeping the line clean and dry is its own project, covered in air compressors for compressed-air torches.
• Pressure and flashback protection. Premix torches carry a real flashback path because the gases are already mixed inside the body, so the flashback protection your torch and gas supply call for is not optional. Follow the manufacturer manual for pressures and for the protection they specify; do not copy a figure from another torch. See flashback arrestors explained for how placement works, and always let the manual set the numbers.

How to choose the right scientific hand torch for your bench

Match the torch to the work and the shop you already run:

• Doing seals, lathe joints, and quartz as your main job: the Nortel Unitorch family is the purpose-built choice, with the 9- and 12-tip heads for more concentrated fire and more standoff.
• Want a proven, tip-driven shop torch on a modest budget: the National 3A-B or 3B-B, with the 4B when the work runs heavier and industrial, or the 6B when you want that flame mounted at a fixed station.
• Already running National-style tips and want one hot point for quartz or lathe boosting: the Nortel Twin Fuel Handtorch takes them, on natural gas or propane.
• Value pick with nozzle options: the Carlisle Universal, spec’d with the 1/4-inch or 3/8-inch nozzle and its matched carburetor.
• The finest seals and smallest quartz detail: the Herbert Arnold Mini for the smallest instruments, or the Premix Hand Torch when you want Arnold’s sealing burner with two needle valves and published pressures.

Whichever you choose, buy the tips or jets alongside the torch, since in this class the tip is half the tool. And if you also need a soft flame for big preheats, pair the premix hand torch with a surface-mix bench burner rather than asking one torch to do both jobs.

Related guides

• Surface mix versus premix torches
• Bench versus hand torch
• Working boro tubing basics
• Glass lathes
• Herbert Arnold torch lineup
• Nortel torch lineup
• Complete glass torch buyer’s guide

Sources

• Scientific Glassblowing Learning Center (ILPI), burners tutorial: premix versus surface mix and tip interchangeability
• Nortel, Unitorch Handtorch product page
• Nortel, Twin Fuel Handtorch product page
• National Torch (Premier Industries), hand torch pages
• Carlisle Machine Works, Universal Hand Torch page
• Herbert Arnold, Arnold Burners catalog (PDF)