Brass and Copper Soldering




About: I've always liked pulling things apart - it's the putting back together again that I have some issues with.

Brass or copper soldering like most things is easy once you know the basics. It’s a great skill to have as it allows you to be able to fabricate and make things out of relatively cheap materials.

I had to learn the hard way how to solder brass and copper – by trial and error. I’ve made plenty of mistakes though and I would have benefitted from a simple guide ao I thought I would put this one together for all those just starting out.

I have made a whole bunch of different projects with brass and copper (see the long list below) but I always assume that everyone knows how to solder. By putting this ‘ible together, my hope is that even if you are a novice, you will be able to make any of the projects listed below.

The project that I made in this 'ible can be found here

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Step 1: ​Tools

The good news is you don’t need many expensive parts or tools to start soldering copper and brass together. In fact, all you really need is some flux, blow torch and some solder. However, there are a few other tools which can help you along the way.

I’ll go into more details on the tools but for the meantime, the list below is what you will need to become an expert in soldering

Parts and Tool List

1. Silver Solder – eBay, Hardware store

2. Blow Torch – eBay, Hardware store

3. Flux – eBay, Hardware store. Can be either paste or liquid flux.

4. Isopropyl alcohol to clean up any flux residue

5. Pliers

6. Vice

7. Small files

8. Wet/dry Sandpaper – from 300 to 1200 grit.

Step 2: Types of Blow Torches

Go to any hardware store and you will come across a whole array of different types of blow torches. I have a few different types that I use for different types of soldering. However, in my opinion, you only need a couple types, a mini one for delicate work, and a larger one.

The blow torch you can see in the images with the red gas cylinder was my go to for a long time. However, I recently got my hands on the brazing torch which is the one with the blue canister and I really like using this one. The flame is hotter and I can control what area's I want to heat up. These are on the more expensive side though so I would start with one like with the red gas can. these take butane and are great for most jobs that you will need to do.

Step 3: Why Silver Solder?

There are a few different types of solder on the market. If you have done any electronic soldering you probably used a lead based solder. This is fine for soldering electronic components together but isn’t really strong enough, nor does it give a great bond, to copper and brass. Your best option is to use a silver solder. There's only about 3.5% silver in the solder (you can get higher amounts but it gets more expensive) but that small amount helps with strength.

Silver soldering, also known as 'hard' soldering or silver brazing, also has a higher melting point then lead so it is important to heat-up the copper/brass sufficiently to get the solder to melt into the joint. More on this later

So to summarize - Silver solder in general has a stronger bond, is less susceptible to mechanical fatigue and creates a more reliable joint.

Step 4: Why Do You Need to Add Flux?

Basically, flux prevents oxidization of the metals being soldered as well as moves it. If your metals are oxidized, then you may have trouble soldering the parts together. Without it, you probably won’t get the solder to flow and join the metal parts together.

There are different types of fluxes that you can use for the job. Some are specific to electronic soldering whilst others are made for brass and coppers soldering. You can get it in liquid or paste form. I prefer the paste but both work fine.

If you go to the plumbing section of your local hardware store, you will be able to find suitable flux to use when soldering brass and copper.

Soldered joints using flux can become corrosive and it’s important to clean off the excess flux to prevent any corrosion from happening. Most of my projects I use sandpaper or a polishing agent to remove the excess flux but you can also use baking soda to neutralize the flux.


1. Make a paste from baking soda and warm water.

2. Apply the paste with a toothbrush to the flux and leave for a couple of minutes

3. Wipe away the baking soda and flux residue with a damp cloth

Step 5: Getting Started – Preparing the Brass/Copper

Soldering works by capillary action – the solder is drawn into the joint by the heat and flux.

1. Place the 2 pieces of copper/brass you want to solder on a hard surface. In this case I’m soldering a copper reducer to a piece of copper pipe.

2. Make sure that you add some flux to the area to be soldered. I use a paste flux which is self-cleaning (although you should still wipe it with some Isopropyl alcohol afterwards.

3. Some people here will say that it is imperative to clean the parts that are to be soldered together. I honestly only do this when the metal is old or dirty, otherwise I don’t bother. If however you want to clean them, then some Isopropyl alcohol will do the job.

4. Place the flux right around the pipe and place the reducer onto the end. Wipe off any excess flux.

5. The solder will want to be pulled downwards (capillary action and gravity) so make sure whatever you are soldering is sitting so the solder can flow into it.

Step 6: Getting Started – Heating the Brass/Copper

1. As the area that you want to add the solder to is relatively large, you can turn the blow torch up to full.

2. Ignite the torch and start to heat the metal up.


- When doing this make sure you don’t just keep the flame on one area. It’s important to move the flame around the area that you want to add solder to and also heat up both the pipe and the copper cap.

- As the flux is inside the area that you want to solder, it’s ok to add the flame directly to this section. If however you are soldering something that has the flux on the outside, then make sure you don’t have the flame directly on the flux. It will burn and become inactive. You need to add the flame around the flux to get it melted and flowing and then you can start to add the flame to the section that you want to add solder to. More on this later.

3. Continue to heat-up the metal until the flux starts to melt, bubble (if you are using a paste) and smoke.

4. Usually, once you see the flux start to smoke and bubble, then the metal is usually hot enough to melt the solder.

Step 7: Getting Started – Adding the Solder

1. Continue to add heat to the metal. However, the heat shouldn’t need to be added directly to the area that you need to solder. If you do add heat to the area whist trying to add solder to the joint, then the solder will most likely melt before it touches the joint.

2. Place the solder on the joint. If it starts to melt then the metal is hot enough, if it doesn’t add some more heat to the area.

3. Move the solder around the joint and make sure you get an even spread of solder. Heat up the area if the solder stops flowing.

4. In a joint like this one which needs to be air tight, it’s better to add too much then not enough. Excess solder can be cleaned-up and filed away.

This is probably one of the easiest joints to solder. The part can easily sit straight, the joint is made to take solder, and any excess solder is hidden mostly inside the parts. However, this is great practice to understand how hot the metal needs to be and also how to get the solder flowing into the joint correctly.
What would happen if you had to clamp 2 parts together sideways and solder these

Step 8: Getting Started – Cleaning and Finishing

As mentioned, the flux that I use is self-cleaning; however, it’s good practice to remove any flux left over. You can use a mixture of baking soda and water to neutralize any of the flux that might be left as it can be acidic. Make it into a paste and with a toothbrush add it to the soldered areas. leave for a minute and wipe away with a damp cloth.

As I usually file and sand the parts, I don't usually worry about removing any left over flux as it usually gets removed this way.

There have been a few comments on this saying it is a waste of time to worry about removing any flux and you should just wipe it away. I've been scouring the internet on this and it all depends on what type of flux you use. I would err on the side of caution and neutralize the flux just to be sure. Again, it really depends on what flux you use and also what you are making.

Step 9: Using a Vice - Part 1

The vice is your best friend when soldering. You can use it as a hard surface, and also hold parts together. The following will show how to solder a part that needs to be clamped together.

1. The parts that I’m clamping together are a piece of copper pipe and a small brass nut. It’s possible that I could solder these parts standing up, but I need the nut to be soldered precisely to the bottom of the tube.

2. Add some flux to the areas that need to take solder

3. Place the 2 parts in a vice. You don’t need to squeeze these parts together tight, just make sure that they are secure.

4. Heat up the metal until the flux starts to smoke and bubble. Make sure you don’t add heat directly to the flux when you initially start to heat the metal up. You can however once the flux has melted.

5. Add solder to the joint. You will see that the solder will start to pool at the bottom of the joint (damn you gravity!). Don’t stress, you can fix this up later.

6. Once you have added enough solder to cover the joint, remove the metal out of the vice (I do this whilst it is still hot by using some pliers – be careful though), and place it on top of the vice. You are now going to re-flow the solder so it evens out on the joint.

7. Heat-up the soldered area until the solder starts to flow. If you don’t bump the metal whilst soldering, then it will stay in place.

8. Clean away any excess flux

Step 10: Using a Vice - Part 2

So what about soldering a part that has a small or difficult joint to solder to? This can be tricky as you need to find a way to clamp these two parts together. A vice can work in most cases but you might have to think creatively. Jigs are also another way to help hold the parts together whilst you add the solder.

1. Place the parts in a vice. If necessary, you may have to use something to help hold everything in place. In this sample, I used a few bearings to sit the pipe onto

2. Add flux to the area that you want to solder.

3. Heat up the section that you want to add solder to. As I have already soldered a few other parts to the copper pipe, I don’t want to add direct heat to those sections if I can help it as it might start the solder flowing again.

4. To get a smaller, concentrated area of heat, turn the blow torch down.

5. Add the solder to the joint. If it is only a small point that you need to solder to, then make sure you add enough solder to enable a secure fix. Be careful though as the solder will have a tendency to flow down and this could cause leakages of the solder.

Step 11: Soldering Small Pieces

Using a large blow torch isn’t feasible when you are trying to solder smaller, delicate pieces together. You need to use a mini blow torch to control the heat and enable you to add solder to the joint.

One of the trickiest parts of soldering small pieces is how to hold them in place whist you heat-up the metal? You need to be able to heat it up with one hand and add the solder with the other. I find that a helping hand like the one in the image below will work in most situations. Sometimes you need to improvise though with what you have around you.

1. Add a small amount of flux to the area you want to solder

2. Heat-up the area with a mini blow torch. Remember not to put the heat directly onto the flux initially or you might burn it.

3. Once the flux starts to smoke you are usually ready to add the solder. Touch the end of the solder to the joint and keep the heat near the area (not on it though)

4. Once the solder has been added, I usually add more heat to the joint to flow the solder and make sure that the joint is secure.

5. Add more solder if necessary

Step 12: Solder Leakage

These usually occur when you are adding more than 1 part to the piece you are soldering. The metal heats up and the solder starts to flow again. If you have added a lot of solder, then there is a good chance that it will leak. You can try to avoid this by not adding direct heat to the part soldered, although this doesn’t always work.

1. If a drip of solder is running down an area that it shouldn’t be, you can wipe it away with a rag whilst still hot. Obviously be careful as it is molten metal. Wiping it away will most likely leave a silver mark but at least there won’t be a blob of solder to deal with

2. You will need to get rid of the solder mark by using some small, fine files. Remove all traces of the solder with the files and then smooth out with some wet and dry sandpaper. I usually use 600 to get the metal smooth again and remove any scratches from the files.

3. If you have a leakage, and the part needs to be airtight, then you need to check and make sure that it still is. If not, then heat-up the area and reflow the solder again. Obviously this could cause problems with other parts soldered to the piece so reduce the heat on the blow torch and take your time.

4. If it is air tight, then you can do a couple of things a. Remove the excess solder with some small, fine files. This will take some time but you will be able to remove the excess solder. Clean-up with some wet/dry sandpaper b. Use a homemade lathe like this one I made and use a file to remove the excess solder. It’s definitely a faster way to do it but you need to be careful that you don’t scratch the metal too much.

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    36 Discussions


    7 months ago on Step 12

    I will help a little more if anyone reads. You never,NEVER heat the pipe when soldering copper tubing as it shows in the video. Always heat the fitting and let the fitting heat the tubing so the solder is pulled into the fitting before you burn the pipe.


    7 months ago on Step 12

    I have to say the DIY crowd are quite funny(OP Included) myself, my father and his father were and are plumbers, all class 2 licensed and this is great and all for putting a little solder on a wire to hold it but do not try any of this in yours or anyone else’s house. I mean the first and one of the most basic parts he says is optional which is as he calls it cleaning the copper. When you see a plumber using a wire brush and sand paper he is cleaning the copper but the point of it to scar and scratch the copper because it gives the solder something to hold onto. If we just wanted to clean the copper we would dab some flux on and then wipe it clean because flux contains acid. But that’s it nothing more to say just please ppl don’t try and DIY things you don’t know anything about. We have worked to get license for a reason as do many others in many occupations I know nothing about.

    1 reply

    Answer 7 months ago

    You can no longer use lead solder at all in any plumbing application. What is called soft solder which you usually see in a little spool is 95/5 which is 95% tin 5% antimony and is lead free. Either are food safe. Silver solder holds up better outdoors because it is harder and stronger but takes more heat to use while soft solder aka 95/5 takes a lot less heat which is why it is used indoors a lot more often than silver solder but it is not as strong so some people will not use it outdoors. Silver solder is also used on precious metals and such. All of it is safe as long as it does not contain lead.


    1 year ago

    Hi, Really great Instructable! I've only applied solder to copper foil for St. Glass projects, so I'm not terribly experienced.

    I wanted to solder some copper jewelry pieces,...problem is the solder color, usually brass or silver. But that's the reason I'm writing. I found a new product (copper colored), 18 ga copper hard solder! Now I can stop "painting or patina-ing the joint afterwards.


    Thought it might be of interest, if the final appearance/color of the solder joint is important, like it is in jewelry work. I have no idea how strong the solder is. I just purchased some & haven't tried it yet. But I thought this may be of interest to some!

    3 replies

    Reply 1 year ago

    Great stuff! This would be perfect to use on projects for copper or brass as it would blend in a whole lot better than solder.


    Reply 1 year ago

    This is copper phosphorus hard solder, you can buy it in the hardware store as well, a big advantage is that you don't need flux!


    Reply 1 year ago

    Thanks Gadisha, Sounds great,...I'll check it out!!!


    1 year ago on Step 8

    In step 8, your photo shows a container of baking powder, but your explanation says baking soda. Do there two items work interchangeably? Is one better than the other?

    1 reply

    Reply 1 year ago

    Sorry for the confusion. It should be baking soda. I've been storing my baking soda in the baking powder container! I'll clear that up in the step.

    Thanks for the heads-up


    1 year ago

    I own a music store and so I solder on brass and silver plated instruments a lot. Here's a tip: If there is somewhere that you absolutely DON'T want solder to stick, paint the area with old fashioned white-out that you get in a bottle at the office supply store.

    When you hit it with the torch the white-out turns black and carbonizes and solder won't stick there. When you're done soldering and after the part has cooled, remove the white-out with a bit of lacquer thinner.

    Oddly enough, I learned this trick not from an instrument repairman, but from an old high school class mate that makes tiny props and things for movies, including some award winners such as Amelie.

    1 reply

    Reply 1 year ago

    This is a great tip - I'm going to try it out on my next copper project - thanks!


    1 year ago

    This is good... Covers the basic necessities, but after doing some (a lot?) you find that getting the heat correct, as goldilocks said 'not too hoo, not too cold' is the key to it all. There's a lot to be said here... Direction of flame,different torches,rising heat (and yes large thermal masses, like a vice absorbing a lot of heat, etc.) but mostly you learn all that stuff with the flame burning, and the solder flowing (or not as the case may be). Flux is needed when at the lower temps.

    As a plumber, I always cleaned everything with sandcloth, then applied flux. Both remove oxides, which interferes w/ good solder flow, the flux removes it chemically instead of mechanically. Later, with refrigeration and high silver contents, the heat is high enough to drive off the oxides so the flux is optional, except with oddball joints of dissimilar metals (steel is a pain!).

    Like I said, good instructable... Practice and learn to control the heat

    1 reply

    Reply 1 year ago

    Very true. I'll add a few comments in the 'ible about the art of getting the right heat.

    Thanks for the info (and reminder!)


    1 year ago

    This is NOT silver soldering. It's soft soldering with lead free solder. Silver solder has a silver content of 40% upwards, not the 3.5% of the stuff you have in the plastic tube! The melting point of 'real' silver solder is over 600 degrees C, what you are using melts at 220 degrees C according to the card. Your copper pipe should be glowing red! Flux for silver soldering usually comes as a powder to be mixed with water when you want to use it. Silver solder is too expensive to be using it in the way you are!

    4 replies

    Reply 1 year ago

    I agree with this Dick, and your advice is not at all nasty. The technique between lead free soft solder as shown here and silver or hard soldering is also different. Hard soldering on jewelry requires tighter joints and finer tolerances and the capillary action is the crux of the joint. Silver solder also partially blends with the base metal whereas soft solder is like surface glue and sits on the copper surface, and thus is a weaker joint. You could do silver soldering on the job you have here but it would require tight fits and heating the copper to cherry red. That said, LSS you did do a good soft solder demonstration.


    Reply 1 year ago

    NO it is NOT silver soldering. I DO however use solder that has 3.5% silver content as YOU have indicated.

    Come on man - If you are going to leave a comment - then at least try and make it constructive and relevant to the Instructable.


    Reply 1 year ago

    I agree with Dick - he pointed at right detail: if you come at shop and ask "silver solder for copper", people think you're the clown. TERMINOLOGY - study first, write next. And don't be that munny-nunny, who cries after every critic!


    Reply 1 year ago

    But you called it 'silver soldering' and said that it was 'hard' soldering. My comment was trying to inform and be constructive. I wouldn't want anyone to believe that what you described was suitable for anything that needed high strength joints such as a copper boiler for a model steam locomotive.