Want to join two metal pieces for good? Our guide breaks down the basics of soldering, step by step. From essential techniques to different soldering types, we’ve got you covered. Plus, we’ll help you pick the perfect kit so you can start soldering like a pro in no time!
Want to join two metal pieces for good? Our guide breaks down the basics of soldering, step by step. From essential techniques to different soldering types, we’ve got you covered. Plus, we’ll help you pick the perfect kit so you can start soldering like a pro in no time!
The two basic types of soldering
First up, a bit of theory. Soldering, by definition, is a technique for joining metal components using a binding agent (the solder). You perform this process at a suitable temperature that melts the solder while keeping the metal components solid. More on this later. The connected pieces themselves remain in a solid state throughout the process.
But what’s the difference between soldering and welding? Both involve high temperatures, a binding agent, and metal components to join. With welding, however, the heat is so intense that the edges of the materials being joined melt as well—not just the welding agent itself.
Now you know the basic concept. So, how do the different soldering techniques compare? There are only two main types:
- Hard soldering (above 450 °C),
- Soft soldering (below 450 °C).
You’ve probably guessed it—the difference lies in the temperature. Next, we’ll dive deeper into the details of hard and soft soldering.
Hard soldering for strong joints
Hard soldering involves the use of solder with a melting point above 450 °C, known as hard solders. These are categorised based on their main components or the elements that significantly influence their properties:
- Copper and copper-based,
- Silver and silver-based,
- Gold-based,
- Platinum-based,
- Palladium,
- Aluminium-based,
- Magnesium-based,
- Nickel-based,
- Manganese, cobalt, and iron,
- Titanium, vanadium, zirconium, and hafnium.
Connections created with hard soldering are renowned for their strength. This method is commonly used for carbon steels, molybdenum, tungsten, chromium, nickel steels, carbide inserts, and even precious metals like gold, silver, bronze, and brass. If you’re looking to solder copper, both hard and soft soldering work well.
Hard soldering requires a propane-oxygen or acetylene-oxygen torch, which is relatively expensive and demands more skill and experience compared to soft soldering. If you’re planning to repair equipment, perform assembly work, or tinker with projects, the upcoming sections of our guide will be invaluable.
Soft soldering: versatile and user-friendly
Soft soldering is a more accessible method requiring less experience and no need for expensive professional equipment. You solder at temperatures below 450 °C, typically using alloys containing bismuth, tin, cadmium, or antimony as binding agents.
Soft soldering is incredibly versatile. You can repair electronics, connect electrical wires, and work with sheets of metal (e.g., for roofing, pipes, or containers). It’s especially handy for joining materials like copper, zinc, steel, and other alloys.
Soldering fundamentals
A soldering iron is your main tool for joining pieces. While models vary in design, they all feature a heated tip. You’ll also need solder wire for the process.
Precision is key in soldering. Start by applying the heated tip to the workpiece—don’t begin with the solder! This prevents the solder from just collecting on the tip. Wait for a moment so both surfaces of the metals you’re joining heat up. This takes a few seconds. Then, bring the solder to the joint. The solder will melt due to the heat from the tip and the workpieces, changing its state. Voilà—the pieces are joined!
Soldering temperatures: with and without lead
Temperature is crucial in soldering. It serves two roles: melting the solder while keeping the workpieces solid. This means the soldering temperature must exceed the solder’s melting point but stay below the melting point of your workpieces.
The melting point of the solder varies based on its composition, particularly its lead content. Lead-based solder melts at lower temperatures (e.g., 183–190 °C). Lead-free solder, on the other hand, has a higher melting point—typically just under 230 °C. This difference makes lead-free solder more challenging to melt but also healthier and more environmentally friendly.
Choose your basic soldering kit
Now that you know the basics of soldering, it’s time to equip your workshop. Start with a soldering iron and some essential accessories. We’ve got you covered with various models and tools to consider.
- Resistor soldering irons – the most popular and affordable type. These come with their own power supply and a heating element that transfers heat to the tip via a wire. If you’re into electronics, this soldering iron is a perfect choice!
- Transformer soldering irons – equipped with a built-in transformer. These models generate heat quickly through the soldering tip by allowing electricity to flow through it. Ideal for tasks like soldering electrical wires.
- Gas and cordless soldering irons – powered by propane-butane gas or batteries. These are highly portable, making them great for use anywhere, even without power supply access. However, they deliver lower power output.
- Soldering stations – include a soldering iron and a control unit with a display. These advanced tools offer precise temperature and power control, allowing you to customise settings to your needs. Some even feature fume extraction or magnifying lamps.
- Hot air soldering stations – an upgrade from standard soldering stations. They’re excellent for soldering and desoldering SMD components. Plus, they’re multi-functional—great for drying paint, removing adhesives, shrinking heat shrink tubing, and more. Choose a station with both soldering tips and hot air for maximum versatility.
Ready to pick your basic kit? Don’t forget to complement it with useful accessories. These tools make soldering easier, more precise, and safer. We recommend:
- Tip cleaner – removes solder and other residues from the soldering tip. Usually made of metal wool.
- Soldering sponge – a cheaper alternative to the cleaner, though less durable. It needs to be dampened before use.
- IC popper/component lifter – helps lift heated components with ease. It consists of a long handle and a fork.
- Fume extractor – essential for professional work, it removes harmful fumes (e.g., lead) produced during soldering. Some extractors feature dual arms to protect two stations at once. Compact models fit neatly on your desk.
- Extractor filters – available in various types and need periodic replacement. For the best filtration, use a three-part filter system (pre-filter, carbon filter, and HEPA filter).
- Magnifying lamp – ensures precision and better visibility. With 5x or 10x magnification, you’ll see every detail. The combination of even lighting, no shadows, and enhanced magnification is often essential for soldering.
- Third hand – a set of clamps to hold all components steady during soldering. The simplest versions have a flexible “gooseneck” and crocodile clips. Advanced models might include a magnifying glass, soldering iron holder, cleaner, and built-in lighting.
- Binding agents – as explained earlier, the type of solder varies based on its melting point. Sold as spooled wire or rods.
- Colophony – a resin often mentioned in soldering guides. We’ll explain its uses in the next section.
What is colophony used for?
Colophony is simply natural resin, a semi-transparent substance that’s yellow or brownish. Available in solid or paste form, it’s highly versatile. In electronics, it speeds up and simplifies soldering while ensuring smoother, shinier joints that are less prone to cracks.
How do you use it? Coating the area to be joined with colophony protects it from oxidation. Soldering involves high heat, which promotes oxidation. Colophony slows this reaction, allowing the molten solder to penetrate the metal before oxidation occurs. Be sure to clean your workpieces of patina, rust, and old solder residues before applying colophony.
Can you solder without colophony?
Technically, yes, you can solder without colophony. However, professionals would never skip this flux. Some solder alloys already include resin, but it’s often not enough for high-quality joints.
Soldering basics – a quick summary
Soldering isn’t complicated, but it does require two things: a bit of practice and a lot of precision. Temperature is key—it determines whether you’ll be hard or soft soldering.
Working with electronics, cables, LEDs, and similar components demands specialised tools. While there are plenty of “how to solder without an iron” guides out there, we strongly recommend at least investing in a basic soldering iron. If you’re soldering regularly, consider an advanced soldering station.
Accessories matter too. Solder and colophony alone won’t cut it. A soldering iron cleaner, holder, and a third hand or magnifying glass will make your work more precise and far easier.
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