.030 VS .035 Flux Core Wire – What are the Differences?

When you use the flux core welding procedures two of the main wire choices you have available are the .030 and the .035 wires. To be able to choose the right wire for the welding you are doing you have to know a few things about the wire, and what sets them apart from each other.

These numbers indicate the thickness of the wire. Of course, you can easily discern that the .35 flux core wire is thicker than the .30 by .005 inches.

Flux Core Wire Basics

Flux core wire is used with an MIG welding process machine. The flux core wire does not require additional shielding gas to be used during the process.

The flux inside the center of the wire melts as it is heated. This flux creates the metal filler for the pieces of metal you are connecting.

Why Use Flux Core?

If you have to weld something that is difficult to get to and do not want to have to carry a lot of os supplies, like an extra shielding gas tank, then flux core reduces the amount of stuff you have to take with you. That makes flux core welding more convenient and less cumbersome than traditional MIG welding procedures are.

If you have ever used an welding machine you know that they are great inside the shop or garage, but not so handy outside where the wind or breeze can interfere with the process. Flux core is able to withstand a larger amount of wind or breeze so it can be performed outside as well as inside the garage or shop.

Using shielding gas presents its own problems. You have to get the ratio of gas set properly and you have to have the gas on hand, and remember to refill the gas bottle, or you can run out of shielding gas before you finish your work. Flux core wire has shielding gas incorporated on the external portions of the wire so no extra tanks are required, and you do not have to worry about the proper settings.

When you use a .035 electrode you will need to have higher amperages available while you are welding. This flux core wire is designed to be used on thicker pieces of metal, and a higher amperage is needed to weld that thicker metal.

The .035 flux core wire is not good to use on metal that is less than a 16 gauge.



  • Thicker metal of greater than 16 gauge
  • Burns hotter than the .030
  • Requires greater amperage from the welding machine 
  • Ideal when welding metal that is ¼” or less in thickness
  • Works best when used with a 210 Volt welding machine
  • Requires no external gas
  • Works well in light winds
  • Produces more slag than the .030 but it has fast freezing characteristics and the slag it produces can easily be removed
  • Has a voltage range of about 15 to 18 volts
  • Can be used with a wire feed speed of 70 to 305 inches per minute


  • Thinner metal like galvanized roofing metal
  • Great for use on auto body repairs
  • Works great with a 110 volt welding machine
  • Requires no external gas
  • Produces very little smoke
  • Produces a reduced amount of splatter
  • Can be used with a wire feed speed of 80 to 445 inches per minute

Final Note

This flux core wire is great, easy to use, and can be mastered by beginners or professionals. To determine which wire you need just consider the machine you are working with and the materials you are working with.

Last Updated on 2 years by Richard Boyer

  • June 8, 2022
Richard Boyer

Richard Boyer has been a professional welder for over 27 years of his life, and now he is a trainer and blogger providing critical information to anyone interested in welding. He is helping out both hobbyists, novice and professional welders to learn newer and better techniques. Read more about me

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