One of the most common technique questions with flux core is do you push or pull when flux core welding, and getting this wrong can mess with penetration and weld quality fast. From real shop and field work, flux core welding is almost always done with a pull (drag) technique, not pushing like solid-wire MIG.
Pulling keeps the slag behind the puddle, improves penetration, and gives you better arc control, especially on thicker metal thicknesses and structural welds. A lot of confusion comes from welders switching between MIG vs TIG and flux core, where torch direction rules change.
This matters because pushing flux core can trap slag, reduce fusion, and weaken the joint. I’ll explain exactly when to pull, rare cases where pushing might work, and how to set your angle for cleaner, stronger flux core welds.
Photo by millerwelds
Understanding the Basics of Flux Core Welding Technique
Flux core welding isn’t some mysterious art—it’s a practical process that lets you weld outdoors without gas, thanks to the flux inside the wire that creates its own shield. But the push or pull debate stems from how the gun angle and travel direction interact with the arc and slag.
Pushing means pointing the gun forward, away from the weld pool, like you’re shoving the bead ahead. Pulling, or dragging, is the opposite: you angle the gun back toward the completed weld, pulling the pool along.
In self-shielded flux core (no external gas), pulling is usually the go-to because it lets the flux gases escape properly and keeps slag from contaminating the pool. I’ve used this on windy job sites repairing excavator buckets, where pushing would just blow the shield away and leave porous welds.
How does it work mechanically? When you pull, the electrode wire feeds into the pool at a 10-15 degree back angle, allowing deeper penetration as the heat builds ahead. Pushing at a 10-15 degree forehand angle can give a wider, flatter bead but risks shallower fusion—great for cosmetic work but risky for structural jobs.
Use pulling when you’re dealing with thicker materials over 1/8 inch, like building frames or welding pipe, because it minimizes distortion by concentrating heat. Pushing shines on thinner gauges, say 16-gauge sheet, to avoid burn-through. Why? The forehand motion spreads the heat, reducing warp on auto body panels or HVAC ducts.
From my shop experience, start with a test piece every time. I once pulled on thin aluminum-coated steel and got great results, but switching to push on the same setup burned holes—lesson learned: match technique to material thickness and joint type.
When Should You Pull in Flux Core Welding?
Pulling is my default for most flux core jobs, especially self-shielded setups on carbon steel. It’s all about control: the drag technique lets you see the pool clearly, reducing the chance of inclusions.
What exactly happens? The wire melts into the pool while the slag forms behind, protecting the cooling weld. This is crucial for vertical or overhead positions, where gravity pulls slag down if you push.
Pull when welding outdoors or in drafts—think construction sites or farm repairs. No gas means less hassle, and pulling enhances the flux’s shielding. I’ve dragged my way through miles of fence posts in gusty winds, getting solid beads without porosity.
Why choose it? Better penetration on rusty or dirty metal, common in real shops. Pulling digs deeper, burning off contaminants. For a T-joint on 1/4-inch plate, pull at 200-220 amps with .035 wire for full fusion without undercut.
Practical tip: Maintain a 1/4-inch stickout—the distance from contact tip to work. Too long, and you’ll get erratic arc; too short, and spatter builds up. I keep a ruler handy for newbies, but after a while, it’s muscle memory. Common mistake? Rushing the travel speed—slow down to 10-15 inches per minute for thick stuff, or you’ll leave cold laps that crack later.
When Is Pushing the Better Choice in Flux Core?
Don’t dismiss pushing entirely—it’s a lifesaver in certain scenarios, like gas-shielded flux core on cleaner metals.
Pushing works by directing the arc forward, creating a spray-like transfer that’s smoother on stainless or alloy steels. The forehand angle pushes slag ahead, ideal for flat positions where you want a cosmetic bead.
Use it when aesthetics matter, such as welding cabinets or decorative railings. On a recent shop project, I pushed on 14-gauge mild steel for a toolbox, getting flat, spatter-free welds that needed zero grinding.
Why? It reduces heat input per inch, minimizing distortion on thin parts. For lap joints, push at 18-22 volts with .030 wire to avoid warping.
But here’s a pro insight: Pushing demands a steadier hand. I’ve seen trainees weave too much, causing overlap beads that look messy. Stick to straight stringers unless filling a wide groove. Safety note: Always wear a respirator with gas-shielded—fumes are no joke, especially indoors.
Mistake to avoid: Ignoring wire diameter. .045 wire pushes well on heavier stock, but switch to .035 for finesse. Test on scrap: If you see worm tracks (slag inclusions), flip to pull.
Comparing Push and Pull Techniques Side by Side
To make this crystal clear, let’s look at a quick comparison. I’ve put together a table based on countless test welds in my garage and on job sites.
| Aspect | Push Technique | Pull Technique |
|---|---|---|
| Penetration | Shallower, better for thin metals | Deeper, ideal for thick plates |
| Bead Appearance | Wider, flatter, more cosmetic | Narrower, convex, stronger structurally |
| Spatter Level | Lower with gas-shielded | Higher, but manageable with anti-spatter |
| Best Positions | Flat, horizontal | All positions, especially vertical/up |
| Shielding | Relies more on gas | Flux does the heavy lifting |
| Common Applications | Sheet metal, auto repair | Structural fab, pipe, heavy equipment |
| Amperage Range | 150-200 amps for .035 wire | 180-250 amps for .035 wire |
Pros of pushing: Faster travel speeds (up to 20 ipm), less fatigue on long runs. Cons: Prone to undercut on edges, harder in wind.
Pulling pros: Forgiving on dirty surfaces, deeper root pass. Cons: More slag cleanup, potential for trapped inclusions if angled wrong.
In practice, I mix them—start with pull for root, switch to push for cap on multi-pass welds.
Setting Up Your Machine for Push or Pull Flux Core
Machine settings are where theory meets reality. Forget the manual’s generic charts; here’s what works in US shops with common welders like Lincoln or Miller.
For pulling self-shielded: Voltage 20-24V, wire speed 250-350 ipm on .035 wire. Amperage hits 180-220. I dial in based on sound—a steady bacon fry means good arc.
Pushing gas-shielded: Drop to 18-22V, 200-300 ipm. Use 75/25 argon/CO2 mix for smoother transfer.
Electrode diameter matters hugely. .030 for thin (under 1/8″), .035 for all-around, .045 for heavy (over 1/4″). I’ve burned through thin stock with .045 pushing—stick to smaller for control.
Joint prep: Bevel edges on thick stuff, 30-45 degrees. Clean with grinder; flux core tolerates rust but not oil. For butt joints, gap 1/16-inch.
Step-by-step setup: 1) Polarity—DCEN for most flux core. 2) Install liner and tip. 3) Feed wire, trim to 1/4″ stickout. 4) Test arc on scrap, adjust till no popping. 5) Weld, maintaining consistent angle.
Anecdote: On a trailer frame, I pulled at too high voltage—got excessive spatter. Dropped 2V, perfect. Always tweak in small increments.
Common Mistakes and How to Fix Them in Flux Core Welding
Even seasoned welders screw up push/pull. Beginners often push everything, like MIG habits, leading to poor penetration.
Mistake: Wrong angle. Fix: Practice 10-15 degrees—use a protractor initially. Bad weld? Grind out, reposition.
Porosity from pushing in wind? Switch to pull, add wind blocks. I’ve used cardboard shields on site.
Undercut on pulls? Slow travel, reduce amps 10-20. For burn-through pushing, increase speed or drop voltage.
Material handling: Store wire dry—moisture causes hydrogen cracking. I keep mine in a heated cabinet.
Safety: Fumes from flux are harsh—ventilate, use extractor. Gloves, helmet with proper shade (10-12).
Shop tip: Record settings in a notebook. What worked on A36 steel pull? 22V, 300 ipm. Saves time next job.
Advanced Tips for Flux Core on Different Materials
Flux core isn’t just mild steel—I’ve used it on stainless, galvanized, even cast iron repairs.
For stainless, gas-shielded push gives clean beads. Wire: E308LT-1, .035 dia, 20V, 200 amps. Pull if outdoors.
Galvanized: Pull always—zinc fumes are toxic, so extract well. Prep by grinding coating off.
Thick plate multi-pass: Pull root, push fills. On 1/2″ A572, root at 220 amps pull, caps at 180 push.
Vertical up: Pull with slight weave, pause on sides. Avoid down—slag runs.
Overhead: Pull short circuits, low amps to prevent drips.
Compatibility: Match wire to base—E71T-1 for general. Check AWS specs.
Lesson: Tried pushing on rusty cast—porous mess. Pulled after cleaning, solid fix.
Integrating Flux Core with Other Processes
Flux core pairs well with SMAW for hybrid jobs. Stick for root in pipe, flux for speed on fills.
Vs MIG: Flux no gas, but more spatter. Push MIG, pull flux.
Amperage overlap: SMAW rods like 7018 at 100-140 amps, flux wire higher.
Electrode sizes: Stick 1/8″ equals flux .035 in output.
When? Use flux for portability, stick for precision.
Tip: Train on both—versatility lands jobs.
Real-World Applications and Case Studies
In fabrication, pull flux on I-beams—deep pen for strength.
Auto repair: Push on panels, low heat.
Farm: Pull on implements, dirty tolerant.
Job: Welded skid steer bucket, pulled .045 at 250 amps—held 10 tons.
Mistake: Pushed on thin gate, warped. Fixed by clamping, slower speed.
Cost: Proper technique saves wire—push uses less, but pull stronger.
I’ve taught apprentices: Start pull, master push later.
Wrapping Up
Getting the push or pull right in flux core isn’t just a technique—it’s the foundation for reliable welds that stand up to daily punishment. You’ve got the complete guide to assess your job, tweak settings, and avoid pitfalls that waste your time.
Whether you’re a hobbyist fixing a mower or a pro on a deadline, this knowledge equips you to produce work you’re proud of, reducing rework and boosting confidence. Always preheat thick sections to 150°F before pulling—that even heat distribution prevents cracks and makes your beads flow like butter.
What Causes Excessive Spatter in Flux Core Welding?
Spatter often comes from high voltage or long stickout. Drop voltage 1-2V, shorten to 3/8″. Clean tip, use anti-spatter spray. In my shop, switching to pull on dirty metal cut spatter by half.
How Do I Choose the Right Wire Diameter for My Project?
Match to thickness: .030 for 18-gauge, .035 for 3/16″, .045 for heavier. Thinner wire for push on thin stuff to avoid burn-through. Test on scrap—I’ve wasted spools ignoring this.
Can I Use Flux Core Wire in a MIG Welder?
Yes, but switch to DCEN polarity and remove gas nozzle for self-shielded. For gas-shielded, keep nozzle. Start low amps, adjust up. Works great for portable setups.
What’s the Best Angle for Pushing or Pulling?
10-15 degrees for both. Too steep, and arc shorts; too flat, poor shield. Practice on plate—mark angles with tape for trainees.
How Do I Fix Porosity in My Flux Core Welds?
Porosity means bad shielding—check wind, clean metal, proper stickout. If pushing, try pulling. Grind out bad spots, reweld slower. Ventilation helps too.