Shielded metal arc welding (SMAW), commonly called stick welding, is a welding process that uses a consumable electrode coated in flux to join metals. An electric arc forms between the electrode and the workpiece, generating temperatures around 9,000°F (5,000°C), which melts both the base metal and the electrode to create a fused joint. It remains one of the most widely used welding methods in the world, holding roughly 26% of the U.S. arc welding market even as more automated processes have gained ground.
How the Process Works
The core of SMAW is simple: you clamp one electrical lead to the workpiece, hold a coated metal rod (the electrode) in a holder connected to the other lead, and strike an arc by touching the electrode tip to the metal and pulling it slightly away. That arc generates intense heat that melts a small area of the base metal and simultaneously melts the tip of the electrode. Small droplets of molten electrode transfer across the arc into the weld pool, adding filler metal that fuses with the base material as it cools.
What makes this process “shielded” is the flux coating on the electrode. As the coating heats up, it does three things at once. First, it releases gases that form a protective atmosphere around the molten weld pool, keeping oxygen and nitrogen in the surrounding air from contaminating the joint. Second, it produces a layer of slag, a glass-like residue that floats on top of the cooling weld bead and shields it while it solidifies. Third, it contains compounds that stabilize the arc and clean impurities from the base metal. Once the weld cools, you chip the slag away to reveal the finished bead underneath.
Because the electrode provides its own shielding gas, SMAW doesn’t require an external gas cylinder. This is a major practical advantage. MIG welding, by comparison, relies on a steady flow of argon or a mixed gas from a tank, which wind can blow away. Stick welding works outdoors, on rooftops, in the field, and even underwater.
Electrode Types and What the Numbers Mean
SMAW electrodes are classified by a coding system from the American Welding Society. A designation like E7018 tells you several things: the “E” stands for electrode, the first two digits (70) indicate the minimum tensile strength of the deposited weld metal in thousands of pounds per square inch, the third digit (1) specifies which welding positions the rod can be used in, and the last digit (8) identifies the flux coating type and the kind of welding current it works with.
Electrodes fall into four broad categories based on how they behave during welding:
- Fast-freeze electrodes (E6010, E6011) deposit metal that solidifies quickly. They dig deep into the base metal and work well on joints with poor fit-up or when welding vertically and overhead, where gravity would pull a slower-cooling puddle out of position.
- Fast-fill electrodes (E7024, E7028) deposit metal rapidly and are designed for large, flat welds where speed matters more than positional flexibility.
- Fill-freeze electrodes (E7014, E6013) split the difference, offering moderate penetration and deposition. They’re particularly good for sheet metal and general-purpose work in all positions.
- Low-hydrogen electrodes (E7018, E7016) are engineered to minimize moisture in the weld. Hydrogen trapped in a cooling weld can cause cracking, especially in higher-carbon and alloy steels. These rods produce high-quality welds with excellent toughness and reduce the need for preheating the base metal.
Amperage and Electrode Size
Choosing the right amperage depends on the electrode diameter and the thickness of the material you’re welding. Too little current and the arc sputters and won’t penetrate; too much and you burn through the metal or produce excessive spatter. For common E6011 rods, typical ranges look like this:
- 3/32″ diameter: 40 to 85 amps, suited for light fabrication and material up to 1/8″ thick.
- 1/8″ diameter: 75 to 125 amps, the most versatile size for general repairs and steel between 1/8″ and 1/4″ thick.
- 5/32″ diameter: 110 to 160 amps, best for structural and heavy-duty work on thicker material.
Most stick welders start in the middle of the recommended range and adjust based on how the arc sounds and how the puddle behaves. A smooth, crackling sound usually indicates good settings, while a loud popping or hissing suggests something needs adjustment.
What Metals You Can Weld
SMAW works on a wide range of ferrous metals. Carbon steel is by far the most common base material, but specialized electrodes exist for stainless steel, cast iron, and various low-alloy steels. The basic principle is to match your filler metal to your base metal: stainless electrode for stainless steel, steel alloy electrode for steel alloy, and so on. Mismatching metals that aren’t metallurgically compatible, like trying to weld steel with a titanium filler, produces weak and unreliable joints.
Where SMAW falls short is on non-ferrous metals. Aluminum, copper, and magnesium are generally welded with other processes like MIG or TIG that offer better control over heat input and shielding. Thin-gauge metals below about 18 gauge can also be difficult with stick welding because the arc’s intensity makes burn-through hard to avoid.
Where SMAW Is Used
Stick welding thrives in environments where portability and ruggedness matter more than speed. Construction sites, pipeline work, shipbuilding, farm equipment repair, and structural steel fabrication all rely heavily on SMAW. The equipment is compact (a power source, a cable, a ground clamp, and a rod holder), easy to transport, and tolerant of less-than-ideal conditions. There’s no gas bottle to haul around and no wire feeder to jam.
Its built-in shielding makes it the default choice for outdoor work where wind would scatter the external gas used by MIG welding. It’s also used for underwater welding, where specialized waterproof electrodes allow divers to make repairs on ship hulls, offshore platforms, and submerged pipelines.
The trade-off is speed. SMAW deposits filler metal at roughly 2.5 to 3.0 kilograms per hour under typical conditions, compared to 3.5 to 4.5 kg/hr for solid-wire MIG welding and 5.5 to 6.4 kg/hr for metal-cored wire processes. Each electrode is also consumed after a few inches of welding, requiring frequent stops to swap in a new rod. For high-volume production work, faster semi-automatic or robotic processes are more economical. But for repair jobs, field work, and situations where setup simplicity trumps raw output, stick welding remains hard to beat.
Eye and Body Protection
The arc in SMAW produces intense ultraviolet and infrared radiation that can cause painful eye burns (sometimes called “arc flash” or “welder’s flash”) within seconds of unprotected exposure. OSHA requires specific filter lens shades based on the amperage you’re running:
- Below 60 amps: minimum shade 7
- 60 to 160 amps: minimum shade 8 (ANSI and AWS recommend shade 10)
- 160 to 250 amps: minimum shade 10 (shade 12 recommended)
- Above 250 amps: minimum shade 11 (shade 14 recommended)
Beyond eye protection, SMAW generates significant spatter (small balls of molten metal), UV radiation that burns exposed skin, and fumes from the flux coating. Leather gloves, a long-sleeve flame-resistant jacket, closed-toe boots, and adequate ventilation are standard. The slag that forms over each weld bead also needs to be chipped off, so safety glasses should stay on even after the arc is extinguished.