Why are Copper Fittings Cleaned before Soldering or Brazing?

For joining metals, both soldering and brazing results in successful outcomes. These methods might have some core differences, yet they have almost similar requirements for carrying out their procedures.

One of the essential requirements for both these methods is clean metal. And since the focus is on copper fittings, it must be clean.

What’s the reason behind it? You’ll get to know it soon. As in this guide, we will tell you why are copper fittings cleaned before soldering or brazing?

Therefore, let’s not waste any moment and jump right into the discussion.

cleaned before soldering or brazing

What is the purpose of surface cleaning in soldering?

Soldering is the method of combining two metals by using a filler metal. The metal used here is solder, which acts as a glue between the metals to be joined.

The common confusion is whether you must melt the metals you want to join. In the case of this method, the only thing you should need to do is melt the solder and apply it between the metal pieces.

For carrying out a successful soldering process, the surface where you need to apply the solder must be clean. The reason is that if the surface has dirt on it, the solder won’t flow properly.

That is why any greasy or dirty surface isn’t ideal for soldering. The dirt present on the surface of the metal pieces creates a barrier. Moreover, you should make sure that both the surface and solder, before melting, are cleaned.

Do you need to clean copper before soldering?

The metal pieces you’ll be joining and the solder should be clean for the soldering to succeed. And that also goes the same for Copper as it is a metal.

Let’s say you’ll be joining the copper pipe fittings. For that, you need to prepare them first.

The process is simple. You should gather all the tools needed to carry out the soldering with Copper. Then, you must cut the copper tube using a tube cutter. The next step is to start the cleaning process.

Here, you should focus on removing all the dirt, copper burrs, and other unwanted things on the surface. The best way to clean those is by using emery cloth. Or else, you can also try fitting-brush to get the same level of cleaning.

And after all this, you may proceed to apply flux and move to the next level to complete soldering, which involves heat and other stuff.

Lastly, while executing all this, make sure your hands are clean. There are high chances that the metal surface might catch dirt from your hands. So, better use clean gloves or be careful while trying out the process.

Why Should Oxide Layers Be Removed Before Soldering?

The oxide layer happens to be a thin coating over the metal surface. As we discuss Copper, a thin layer over Copper can be an oxide layer, also called copper oxide.

Before soldering, you should remove the oxide layers because it prevents the solder or brazing filler from bonding with the metal. It hampers the overall soldering process, and you need to take action as soon as possible.

You need to use flux to get rid of these oxide layers. Soldering flux is a kind of metal purifying chemical agent that will help you to clean the impurities. It can remove oxidized parts from the metal surface you want to solder and the filler metal that is later melted to solder.

Another thing about using flux is that it prevents the metal surface from re-oxidation. As a result, you remain tension-free when applying flux for deoxidizing.

Why should you clean copper fittings before soldering or brazing?

You already know the importance of cleaning the metal pieces before carrying out soldering.

The first and foremost thing you need to prepare the metal tubes when it comes to brazing. The metallic surfaces should be transparent here, just like before soldering.

That said, here are some of the prominent reasons for cleaning copper fittings:


If you apply solder paste while copper tubing and don’t bond very well, there are some issues.

You can resolve such issues by removing the oxide layer formed on the copper surface. These oxide layers are thin and aren’t very solder-friendly. It prevents the wetting of the copper surface, which is a must need for soldering or brazing.

That’s why you may use soldering flux to remove the oxide layer.

Grease and debris

Other than the oxide layers on the copper surface, the debris settling or the greasy elements can hamper brazing or soldering.

Greasy elements might settle right from your hands. If your hands are dirty and you touch the Copper’s bare hand, the surface will have impurities. The same goes for debris, as it can settle if you keep the Copper in an untidy or dirty environment.

To get rid of this, you can take a piece of cloth and alcohol to clean the base metal.


Both soldering and brazing let you join metal pieces effectively. They have some fundamental differences, but the result is the same.

But you won’t be able to get the result when the surfaces of the pieces of metal are dirty. The impurities present will hinder the bonding process, and that’s why you must clean the metal part before soldering or brazing.

With the insights provided in this guide, we believe that you will find it much easy while join copper fittings.