Gas Soldering Irons


PG509 Gas Soldering Iron

Introduction to Gas Soldering Irons - now on Kindle

Over the years, portable butane-fuelled soldering irons have become readily available and there’s now more choice than ever before. So is a gas soldering iron right for you? How do they work and should you buy one? Hopefully the answer to these questions and more besides will be found in the Introduction to Gas Soldering Irons. As an added bonus, in Part Two some typical gas soldering irons are reviewed to help you decide whether a butane iron is a worthwhile buy and what to look out for before you invest in one.

Using friendly, non-technical language and colour photos the Introduction to Gas Soldering Irons explains how different types of gas iron operate, what features to look out for, some key facts about butane, important safety aspects you need to know about and how to get the best out of a typical unit. Although it's written with electronics users in mind, others may find it useful too and it's a must-read for anyone thinking of buying a gas soldering iron. Check the free Kindle preview to learn more.

You don't need a Kindle to read it as free readers for Windows PC, Mac, Android platforms are available from Amazon. You can order the Basic Soldering Guide from Amazon here (USA) or here (UK). Free preview available. Check it on your Kindle, PC or tablet now!

This article outlines the basic things to look for when buying a gas soldering iron.

Cordless soldering irons are great for quick repairs. A gas powered soldering iron is ideal for working in locations where there may be no mains power supply available. They can reach into equipment without having to trail a power cord, so they work well in difficult or inaccessible areas. But they can be expensive to buy — until now. We review a typical gas soldering iron kit which is aimed at the hobbyist. At the time of writing, the item described here is on sale via the web, including eBay.

Gas-powered soldering irons are particularly useful for occasional repairs, when it may not be worth plugging in an electric iron and waiting for it to warm up to the correct operating temperature. If you simply can’t be bothered to set up an electric iron for a quick repair job, then a gas soldering iron can be your friend.

Elsewhere I have reviewed the so-called “Cold heat Soldering Iron” and concluded that in spite of its battery-powered convenience and clever materials technology, it is unsuitable for electronic repairs that involve any form of semiconductor components. The very low impedance voltage that exists across the two electrodes can cause permanent damage to semiconductor junctions. The tip is also delicate and easy to damage. The makers eventually went out of business.

Gas-powered irons are a sensible solution for electronics use where cordless convenience is required, though only a more demanding hobbyist, or a regular repair technician, could probably justify buying one. However, cut-price ones are now commonly sold on e.g. eBay including the type reviewed here.

Butane gas refill valveA gas iron is butane powered and can be refilled with ordinary cigarette lighter butane aerosols. Butane irons can be used for several purposes, often having a mini hot-air nozzle (suitable for e.g. heat shrink tubing), possibly a hot knife (for sealing polythene, cutting and sealing nylon rope, or cutting and shaping thermoplastics), a higher temperature bunsen tip for heating metal parts, and of course they usually include a soldering tip for electronics repairs.

Gas soldering irons - what to look for

Gas soldering iron hot air blowerGas soldering irons rely on the use of a catalyst working in exactly the same way that butane powered hair curlers/ tongs work. Once the butane gas has been ignited and the catalyst has heated in the preliminary stage, unburnt butane gas continues to pass over the hot catalytic element (rather than burning off with a flame) which fuels the burning action to create a red-hot temperature.

Note that this is different from a conventional butane mini gas torch, which simply uses a series of jets to generate a bunsen flame. Such a naked flame is only of use in general high temperature working of materials. The heat is usually too fierce and uncontrolled, causing ‘collateral damage’ and burning with e.g. heatshrink tubing, and is generally unsuited for electronics soldering.

A good quality gas soldering iron has a range of tips that makes the iron a versatile hand tool for electronics assembly or DIY. Some irons have a catalyst built into every tip, regardless of function (hot air blower, soldering iron, hot knife etc.) whereas other types (such as the one reviewed later on) use just one catalyst, onto which a suitable metal working tip is fitted.

The main point is that if a single catalyst is used, it may be cheaper to buy initially but if the catalyst is damaged then pretty much the whole iron is rendered useless. Nevertheless this type of iron is fine for general hobby or occasional repair use. More expensive irons may have a range of different tips available, each with a built-in catalyst.

A feature worth watching out for is piezo spark ignition. This offers convenient single touch lighting of the gas, though many cheaper irons seem to use a simple cigarette-type flint lighter to provide the necessary spark. (Spare flints are soemtimes available from tobacconists or corner shops, e.g. under the Ronson brand).

Once the gas has been ignited, what happens next depends on the design of iron. Some of them need a short time before the flame extinguishes by itself, after which the catalyst glows red hot and the tip heats up. Others (including the one reviewed here) require that the user presses a switch to extinguish the naked flame manually, after which the catalytic heating process continues to warm up the tip.

Other useful features include:

At the time of writing, there are an increasing number of gas irons available, from famous makes including Weller (now owned by Cooper Hand Tools) and Antex as well as a number of less well known brands. Expect to pay upwards of £40 ($75) or more for a professional quality gas soldering iron, with piezo ignition and a kit of tips.

Gas Soldering Iron Review

The piezo-ignition iron reviewed here is available online at a remarkably low price, and seems to offer everything that a hobbyist is looking for in a gas-powered iron, at a very low cost, so I decided to try one.

The iron is a single-catalyst iron in a kit containing a number of interchangeable tips. The overall design is a bit clunky and functional-looking compared with more expensive counterparts, but everything needed is included in the kit, and what is amazing at this price level is that it has piezo ignition rather than flint ignition.

The iron is presented in a kit as follows:

Gas soldering iron kit
Gas soldering iron in use
Pop out bench stand
Soldering Iron Kit - contains a gas torch with cap, bit holder, various soldering bits, a hot knife attachment, sponge and some solder, in a presentation box. The main body has a pop-out stand to raise the tip off the bench and stop the iron rolling about.
main soldering iron torch Gas soldering iron controls
Above, the main soldering iron torch with no attachments fitted at all (gas mini blowtorch mode).
The controls are fairly functional - a sliding gas switch turns on the gas flow (press the Latch button and slide back, to turn it off again); piezo sparker slide switch ignites the gas flow, and a flame-out push button extinguishes the flame, then the catalytic heating action begins. The flame adjuster control is underneath (it's above the letter "a" in "Gas Switch").

The iron has a refill valve in the bottom and a control valve in the plastic body that regulates the gas flow. The gas is turned on via a small slider switch and the piezo ignition uses a large spring-loaded slide switch.

Unfortunately the writer’s initial trials did not get off to a flying start: I was unsuccessful in trying to fill the iron with butane gas and wasted a third of a butane refill can (and emptied it, in fact). The gas leaked everywhere and none was retained in the iron itself. It was impossible to ignite it, and so with confidence severely dented it was exchanged for another iron. Happily this was refuelled successfully and it ignited perfectly first time.

In its most basic “continuous flame” mode of operation, the iron is fitted with a bare metal sleeve, which screws onto the end to provide a pencil flame/ blowtorch function. Simply turn the gas on and click the piezo sparker and the torch lights first time to generate a small bunsen flame. Use the flow control to set the flame height from ½” to 1½”. This would be used for e.g. heating metal components. The hottest part of the flame is the tip of the inner blue bunsen cone.

On-off Interlock

The unit is designed such that merely by sliding the switch forward, the gas is turned on without any safety interlock acting to prevent inadvertent operation. However a latch button on the gas on/off switch has to be pressed first, in order to turn the gas off again. Thus the flame locks in the 'on' mode, which is something to be mindful about. More on the implications of this later.

For soldering or hot knife operation, the catalyst unit is fitted into the metal sleeve (see photos): it has an exhaust port for the hot gases that must be facing upwards, away from the workpiece. Otherwise there is the risk of hot exhaust gas damaging the workpiece.

butane flame
valve control
ceramic burner
The butane flame (gas torch mode). A simple lever on the body near the pop-out stand controls the gas flow. It needs setting to MAX when igniting the gas. Removing the steel sleeve reveals the ceramic inner burner. The catalyst (when used) drops into the sleeve and the large plastic/ brass ring nut is tightened down again to hold everything together.
hot air blower gas catalyst burner
warning label
The gas torch with the catalyst fitted: after ignition, press the 'flame out' button and the catalyst element takes over and glows red hot. In this mode the unit is a useful hot air blower. The female threads accept the chisel or pointed soldering tip or hot knife attachment, which heat up through conduction. Hot gas is exhausted out through the port. Use the flow control to adjust the heat. The warning label clearly advises the user to point the exhaust port upwards - otherwise hot air may damage surrounding areas. This is especially important in confined spaces such as within electronics equipment.

The end of the catalyst unit has a female thread that holds a tip – a large hot knife attachment, or choose from three different soldering tips, or a hot mini ‘poker’ needle whose purpose was a bit indeterminate! Possibly for pokerwork or carving or making holes in thermoplastics. The iron works by thermal conduction, with the hot air blasting the metal tip and the hot exhaust gas venting out from the port. Without any tip being fitted, a useful mini hot air blower is created that can be used for reworking plastics or for heatshrink tubing.

Having fitted the catalyst unit, it was found that the flame would only ignite properly if the flow control was at maximum, when the flame would light first time. There was a change in the sound made, from a hiss to a quiet roar.

Unlike some gas irons, this has a “flame-out” button, which then needs to be pressed in order to extinguish the internal flame – the catalyst takes over and glows red hot, fuelled by unburnt butane. A warning label on the iron clearly instructs the user about this aspect.

To extinguish the flame, the metal release button is pressed and the on/off switch slid back to the ‘off’ position. It should be noted that in catalyst mode, the heat flow will automatically be restored if the on/off switch is turned back on within about 20 seconds or so: the spark ignition is not necessary.

Having fitted a soldering iron tip, the golden rule of using a new iron is that fresh solder must be melted onto it straight away (tinning the tip). Use generous quantities of fresh solder and wipe the hot tip on the damp sponge. Repeat several times. This will act to preserve the tip and ensures that new solder will flow onto the tip properly, rather than ‘beading off’ due to impurities and oxides forming. The range of accessories provided is shown below.

Hot air blower Hot air blower - catalyst element fitted. Note the hot gas exhaust port. Before using the iron, ensure the port is pointing upwards.
Pointed soldering iron bit Pointed soldering iron bit
Chisel soldering tip Chisel soldering tip
Anvil soldering tip Anvil soldering tip
Hot knife attachment Hot knife attachment for e.g. cutting and sealing nylon rope or perhaps polythene bags, in well ventilated areas.
Needle tip Needle tip for e.g. pokerwork or working with plastics. Possibly for sealing polythene bags.
An alternative way of mounting the iron for hands-free use An alternative way of mounting the iron for hands-free use - a popular hobby spring clip (not supplied) can act as a bipod!

In use, the bulky body of the iron (about the size of a small tube of toothpaste) and its functional ‘feel’ is more cumbersome than a dainty pencil electric iron, so it may take a little getting used to. Even so it was possible to make satisfactory solder joints or simple repairs, as well as using the iron for other tasks: I used it to successfully bend back some "tired" plastic mounting clips on a Dremel rechargeable battery. Model engineering types could soon make their own tips as well.

As the iron includes three different soldering tips (which is two more than some more expensive kits provide), users should be able to adapt their technique using the tip that works best for them. All the soldering tips are on the larger side (1/8" and 5/32") and delicate p.c.b./ p.w.b. work could be difficult. For hands-free use, try a small Wolfcraft hobby clip, fitted to the body as shown in the photo. You can then hold wires etc. in the stream of hot air.

The pop-out stand ensures the iron does not roll around on the bench, and it raises the tip away from the bench surface. The kit includes a tube of electronics solder and a piece of cellulose sponge in a tin holder completes the kit - the cordless gas iron includes everything necessary for making quick or 'spot' repairs.

A strange interlock

Some confusing discrepancies between the basic printed instructions and actual usage were noted. Earlier I mentioned that the on/ off slider switch had a metal button that is pressed before the switch can be turned off.

On the sample tested:

The operation of the controls soon become evident in use but we found the instructions were very unhelpful. The net effect is that the interlock, it seems to the writer, works in reverse to a common sense approach: it is very easy to turn the gas on (just slide the switch forward) and more difficult to turn it off (needing to press the button and then slide the switch back). Hence the flame "locks on" in use.

An important point to remember is that after finishing a job and turning off the gas, the hot catalyst will glow hot again if the gas is turned back on within say 20 seconds. So if the on/off switch is slid forward, the iron will heat itself back up. Caution may be needed to ensure the iron is not accidentally re-activated when it is put away.

A plastic vented cap is supplied with the iron.A plastic vented cap is supplied with the iron. We're unsure about the long clip that reaches over the on/off slider, presumably it helps prevent the gas switch being turned on when the cap is in place. Or it is designed to loosen off the cap automatically when the gas is turned on.

Even with the cap fitted, though, the on/off switch can be slid forward and on our sample it took only 3mm of movement to switch the gas on. If the catalyst is hot, it will start heating again, this time with the plastic cap still fitted. The plastic cap did not effectively prevent the iron from being turned on again.

The iron is considered safe enough provided care is taken to avoid accidentally switching the gas on (or back on again), with or without the cap in place, when putting the iron away. Of course, the hot iron or the bits can not be stored in the plastic presentation box, and there isn't room to store the iron in the box with its cap fitted.

Note: This article was previously published as a review of the Maplin PG-509 gas Soldering Iron, now discontinued by them. Identical units are available online. Hopefully the above review of a typical iron will give readers some pointers to look out for when buying and using a gas soldering iron.

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All images and text © Copyright A R Winstanley January 2007. Reproduction or re-use prohibited. Updated 23rd August 2016. Email the author.