Why Use Flux Core Wire Title Image

When you’re not sure which wire to choose.

And you have a choice.

Between Flux Core welding with Flux core wire. Or MIG welding with gas.

How do you know which is the best to pick?

Read on to find out more …

Why Use Flux Core Wire And What Do You Use It For?

  • Because it’s better with ‘dirty’ metal. Metal with rust, galvanization or oil on.
  • Use gasless flux core wire and weld with no tank of gas.
  • It’s ideal for welding outside.
  • You can weld quickly. Because your filler wire goes into your weld at a high rate.
  • The right flux core wire means you can weld in all positions.

You’ll Find Two Types Of Flux Core Wire

The first thing to realize is that there are two types of flux core wire.

There is gasless flux core wire. You’ll also see it called self shielded.

You use this flux core welding wire without separate shielding gas.

Gas less flux core wire is more often used by the home workshop welder.

And then there is gas shielded.

You may hear it called dual shielded or double shielded flux core wire.  Commercial welding uses a lot of this flux core wire. And you’ll need a tank of shielding gas to weld with it.  That’s why it has the name dual or double shielded.

With gas shielded flux core wire your hot metal has two shields from the air. The separate gas and the gas generated by the flux core.

If you are curious to know me you’ll find an article on the site all about these two wires. You can click over to it here.

Why Use Flux Core Wire?

1. When You Need To Weld Near Your Broken Metal

When you’ve that fence that needs repairing. Or you’ve a broken farm machinery part.

Both of these jobs. Along with many others are not easily carried into your workshop. 

Or you can’t get them in your workshop.

Like a part on a piece of farm machinery you can’t get in the door.

Then your only choice is to take your welding to the piece you need to repair.

You can use gasless flux core wire welding when you’re welding outdoors. Because you’ve less to carry with you to your weld site.

All you’ll need is …

A way to generate the power your flux core welder needs.

Your flux core welder filled with your gasless flux core wire.

You’ll have no shielding gas to carry with you. And no need to work out how you’re going to transport your tank of compressed gas to where you’re flux core welding.

Take Your Spool Of Flux Core Wire

2. When You’re New To Welding Flux Core Wire Is Your Friend

Because self shielded flux cored wire is easily used by you as beginner welder.


You’ve a simple set up for your home work shop or garage.

You simply fill your flux core welder. Or your MIG welder with flux cored wire. You then set your welder’s output voltage and wire feed speed.

And you’re good to weld.

You’ve no separate tank of shielding gas to buy, transport or use for your weld.

And flux core wire is more forgiving of the skill. Or rather lack of skill when you’re new to welding.

You’ll get to a nice finished weld much quicker.

You’ll find a collection of the best flux core welders under $200 here. Take a look.

3. When You’ve Some Dirty Steel To Weld. Find Yourself Some Flux Core

Why is that?

The flux in your flux core wire has oxidizers and scavengers. They lift the contaminants in your weld out and up to the surface.

What are the things that would make my metal ‘dirty’?

Rust, galvanization, oil, mill scale or paint on the joint you’re welding.

Your flux core wire either burns them off in the fumes. Or they sit in your welding slag.

The welding slag is a covering over your weld you tap off when you’ve finished welding and your metal has cooled.

If you want to know more about welding slag then have a look at this article on the site here.

Even though flux core wire is good with dirty metal. You’ll always find it’s best to clean as much rust, galvanization, oil, mill scale or paint off.

Flux core is more tolerant of dirty steel. But where you can’t get your joint scrupulously clean flux core wire is your savior.

Close Up of Mig Welding Flux Core

4. When You’ve Got Thicker Metal Gauges To Weld Use Flux Core Wire

You’ll find flux core wire welding is the best on thicker gauges of metal – 18 gauge and thicker.


Flux core wire gives you more weld for the electrical power you put in.  It you’ve a MIG welder that struggles welding 3/16th steel. Pop in flux core wire and you can weld much thicker metal.

And gas shielded flux core wire is even better at this.  You can weld thick metals and fast. And have a great finished result with gas shielded flux core wire.

5. When You’re Only Welding Sometimes And Can’t Afford An Expensive Welder

Why’s that?

You can buy yourself a flux core only welder and use flux core wire. When you’re welding small amounts. And welding mild steel then using flux core wire in a flux core only welder is a cheapest option.

When To Use Flux Core Wire

1. When There’s A Breeze Where You’re Welding

Flux core welding is way more accepting of wind around your weld site.  When you need to weld outside your workshop.

It’s the best when you’re literally welding in a field.

Because the flux inside your flux cored wire creates the shielding gas you need. And this gas protects your hot molten metal.

And it’s delivered, right there at your weld point.

You can weld when it’s windy.

MIG welding puts your shielding gas over your weld. And its separate to the wire. And this means to weld outside in any sort of a breeze you’d need some form of wind shield. Or tenting set up to protect your weld area.

Welding with flux core wire is way easier.

Ok, so it is possible for a very high breeze to blow your flux core shielding away. Welding in a gale is not for the faint hearted.

When there’s a moderate breeze you use flux core wire to weld.

Flux Core Welding Outside
Flux Core Welding Outside

2. When You Need To Weld Fast Use Flux Core Wire

Or you’ve got a ton of welding to do.

Why is that?

When you use flux core wire your welding is a hotter process.

Flux core wire also puts your filler metal into the joint faster.  You’ll also see this called a high deposition rate.

And you’ll find this especially true when your talking about gas shielded flux core wire.

This is why commercial shops love gas shielded flux core wire.

You can weld thick metals and fast. And not only that with gas shielded flux core wire the slag is easy to remove.

Leaving you with a lovely clean weld.

3. When Your Weld Is In An Awkward Spot

When you can’t easily bring the piece you need to weld onto the flat. And you’ve got to do a vertical. Or even overhead weld. Then pick flux core wire because that’s made for all positions.

Because from this point of view flux core wire is better than solid MIG welding wire.

With it you can get your out of position weld done.

In Summary What Is Flux Cored Welding Wire Used For?

  • For welding outside where your broken or cracked metal is.
  • You can learn your welding skills with flux core wire.
  • For those situations when you can’t get your metal completely clean.
  • For welding over galvanized steel use flux core wire.
  • For thicker metal when you have a lower powered welder.
  • When you can only afford an entry level flux core welder. You’ll get some good welds done with flux core wire.
  • Use gas shielded flux core wire when you’ve thick metal, lots of welding to do and need fast clean welds.
  • Use flux core wire for welding out of position.
  • Want a strong clean weld? Then you use flux core wire.

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Flux Core Welding Galvanized Steel 16 Things To Know