What SMAW Is and Why It Matters

SMAW stands for Shielded Metal Arc Welding, and it is the process most people picture when they think of stick welding. A welder holds a metal rod (called an electrode) in a clamp, strikes an arc between the rod and the workpiece, and the rod melts to form a joint. The rod itself is coated in flux — a chemical compound that burns away as you weld, creating a gas shield that protects the molten metal from oxygen and other contaminants in the air.

SMAW is one of the oldest and most portable welding methods still in regular use. You do not need compressed gas cylinders, which makes it practical for field work, outdoor jobs, and places where gas delivery is difficult. The equipment is straightforward, durable, and relatively inexpensive compared to other arc welding processes. That simplicity is also why SMAW remains the standard way to teach welding fundamentals — understanding how SMAW works teaches you the core principles that explore to nearly every other welding process.

Key Takeaways

  • SMAW uses a coated metal rod (electrode) that melts to form a weld, with the coating creating a protective gas shield as it burns.
  • The process requires striking an arc, maintaining the correct arc length, and moving the electrode at a steady pace to create a sound bead.
  • Different electrode types and sizes are chosen based on the metal being welded, the joint position, and the thickness of the material.
  • SMAW produces slag — a crusty byproduct that must be chipped away after each pass — which is one of the main differences from gas-shielded processes.
  • The equipment needed is minimal: a power source, electrode holder, ground clamp, and the electrodes themselves.

The Three Core Parts of the SMAW Setup

Every SMAW job requires three things: a welding power source, an electrode holder with a cable, and a ground clamp with its own cable. The power source is a machine that converts wall power (or generator power) into the high current needed to strike and maintain an arc. It sits on the ground or a cart and can run on either AC (alternating current) or DC (direct current), depending on the machine and the electrode type.

The electrode holder is a clamp that grips the end of the stick electrode and carries current to it. It is connected to the power source by a heavy cable, usually red or black. The ground clamp — also called a work clamp — connects to the workpiece and completes the circuit. Current flows from the power source through the electrode holder to the electrode, jumps the arc gap to the workpiece, and returns through the ground clamp to the power source. Without a solid ground connection, you cannot strike an arc or maintain one.

The electrode itself is a metal rod coated in flux. The rod is the filler metal — it melts and becomes part of the weld. The flux coating serves multiple purposes: it creates the shielding gas, helps the molten metal flow smoothly, adds chemical elements to strengthen the weld, and leaves behind slag that protects the cooling weld from the air.

How to Strike and Maintain an Arc

Striking an arc is the first skill every SMAW welder learns. You hold the electrode at a shallow angle (about 15 to 30 degrees from vertical) and bring the tip close to the workpiece. Then you either tap the electrode against the metal and pull back slightly, or drag it lightly across the surface. Either motion creates a gap where the electrical resistance is high enough to ionize the air and create a spark — the arc.

Once the arc is lit, you maintain it by keeping the electrode tip roughly 1/8 inch away from the workpiece. This distance is called the arc length, and it is the single most important thing to control while welding. If you hold the electrode too far away, the arc breaks and you lose the weld. If you push it too close, the electrode sticks to the workpiece and the arc dies. The right distance feels like a steady hum or crackle, and the molten pool glows a bright orange or yellow.

As the electrode melts, you move it forward along the joint at a steady pace — typically a few inches per second, though this varies with electrode size and the thickness of the metal. You also feed the electrode downward slightly to maintain that 1/8 inch gap as the rod gets shorter. This combination of forward motion and downward feed is what creates a uniform bead.

Understanding Electrode Types and Selection

Electrodes are labeled with a four or five-digit code that tells you what the rod is made of and how to use it. The most common code is E7018, which means the electrode produces a weld with a tensile strength of 70,000 pounds per square inch (the "70"), contains 1% manganese (the "1"), and is designed for all-position welding with a low-hydrogen coating (the "18"). Other common types include E6010 (a fast-freezing electrode used for root passes and outdoor work), E7024 (a fast-fill electrode for flat and horizontal positions), and E308 (a stainless steel electrode).

Choosing the right electrode depends on three things: the metal you are welding (mild steel, stainless steel, cast iron, etc.), the position of the joint (flat, horizontal, vertical, or overhead), and the thickness of the material. A thicker piece of steel usually requires a larger diameter electrode and multiple passes. A thin piece requires a smaller electrode and lighter current to avoid burning through. Your electrode supplier or a welding handbook will list the recommended current range for each electrode size — this is the amperage you set on the power source.

What Slag Is and Why You Have to Remove It

Slag is the crusty, glass-like coating that forms on top of the weld after it cools. It is created when the flux coating burns away and combines with impurities in the metal. Slag protects the weld from oxidation while it cools, which is why it forms in the first place. However, slag also hides the weld underneath, and if you lay down a second pass without removing the slag from the first pass, the new metal will not bond properly to the old metal.

After each pass, you chip away the slag using a chipping hammer — a small hand tool with a flat end and a pointed end. You strike the slag at an angle to break it loose, then brush it away with a wire brush. This step takes only a minute or two, but skipping it is one of the most common reasons for weak welds. On a multi-pass weld, you repeat this cycle: weld a pass, let it cool slightly, chip the slag, brush it clean, and lay down the next pass.

Common Mistakes and How to Avoid Them

The most frequent error beginners make is holding the electrode at the wrong angle. The rod should be tilted slightly in the direction you are moving — this is called the travel angle — and tilted slightly to the side — this is called the work angle. If you hold it straight up and down, the weld will be uneven and weak. A good rule of thumb is to keep the electrode at about 15 degrees from vertical in the direction of travel, and perpendicular to the joint (90 degrees to the line of the weld).

Another common mistake is moving too fast or too slow. If you move too fast, you do not deposit enough metal and the weld is thin and weak. If you move too slow, you deposit too much metal and the weld becomes thick and hard to control. The speed should be steady and smooth — imagine you are drawing a line with a pencil, not painting with a brush.

A third mistake is not cleaning the workpiece before you start. Rust, paint, oil, and dirt all interfere with the arc and create weak welds. Always wire brush or grind the area where you are going to weld, and clean a few inches on either side of the joint. This takes five minutes and prevents hours of rework.

Setting Up Your Power Source and Ground Connection

Before you strike your first arc, you need to set the current on the power source. The electrode manufacturer prints a recommended range on the box — for example, E7018 might be 90 to 150 amps depending on the rod diameter. Start at the middle of the range and adjust based on how the weld looks. If the arc is hard to maintain and the metal does not flow smoothly, increase the current. If the electrode melts too fast and the weld is too wide, decrease it.

The ground clamp must be attached to the workpiece as close as possible to where you are welding. If the clamp is far away, the current has to travel a long distance through the metal, and you lose voltage and heat at the arc. A poor ground connection is one of the hardest problems to diagnose because the symptoms look like operator error — the arc is hard to start, it keeps breaking, and the weld looks rough. Always check your ground clamp first if something feels wrong.

If you are using DC current, pay attention to polarity. Most SMAW electrodes work best with DC electrode positive (DCEP), which means the electrode is connected to the positive terminal of the power source. Some electrodes, like E6010, can run on either AC or DC. Check the electrode box to be sure.

Frequently Asked Questions

What is the difference between SMAW and MIG welding?

SMAW uses a coated stick electrode and produces slag that must be chipped away. MIG uses a continuous wire fed through a gun and a separate shielding gas, so there is no slag. SMAW is more portable and works better outdoors; MIG is faster and leaves a cleaner surface. Both are arc welding processes, but the equipment and technique are quite different.

Can you weld overhead with SMAW?

Yes, SMAW is one of the few processes that works reliably in all positions, including overhead. You use a low-hydrogen electrode like E7018, reduce the current slightly to keep the molten pool small, and work slowly. The slag helps hold the metal in place while it cools, which is why overhead welding is possible with SMAW but harder with some other processes.

How long does an electrode last?

A typical 1/8 inch diameter electrode is about 14 inches long and lasts roughly 5 to 10 minutes of actual welding time, depending on how fast you move and how much current you use. As the rod gets shorter, it becomes harder to hold and control, so most welders throw it away when about 2 inches remain. The stub is waste and cannot be reused.

What causes porosity in a SMAW weld?

Porosity — small holes or voids in the weld — usually comes from dirty metal, a poor ground connection, or moving too fast. Rust and oil trap gas bubbles in the molten metal, and those bubbles get trapped as the metal cools. Always clean the workpiece, check your ground clamp, and maintain a steady travel speed to prevent it.

Do I need a special power source for SMAW, or can I use any welder?

Any AC or DC arc welding power source will work for SMAW. Stick welders are straightforward machines with just a few controls: current adjustment, polarity selection (if DC), and sometimes a duty cycle rating. You do not need a fancy machine to learn SMAW — a basic stick welder costs less than most other types and will last for years with minimal maintenance.