Quick Guide: What Is Rosin Core Solder?

• Post By: Brandon M. Fox  • Updated: 06/02/21
• Soldering

Soldering is a common term in the manufacture of electronics. It is the process by which different metal components are joined together using solder material to form a bond between the various metals or metal alloys.

Soldering at its core can occur in different ways and with other materials. There are also different types of solder, from lead-free solder to lead-based solders. However, we will restrict ourselves to the rosin core solder, a popular type of soldering material.

What is rosin core solder?

This type of solder is soldering used predominantly to solder surfaces that don’t need any flux residues removed. If you are familiar with Rosin-based flux, you must be aware that they tend to leave behind no residues whenever they are used.

Rosin core solder wire has mild amounts of flux, which means you won’t have to remove any additional flux. Some parts would require too much effort to remove flux residues. That’s where the Rosin core solder comes in.

Rosin core solders are popular because they aren’t as corrosive as other types of solders. They also won’t leave behind any residues, making them the perfect solder material for parts that would difficult to remove residues if there were any.

Rosin core solder is derived from pine extract resin. Distilling it with flux gives a type of solder that creates powerful bonds ideal for repairing and joining metals on circuit boards. It can either be lead-free or lead-based.

What is rosin core solder used for?

Rosin core is ideal for brittle or fragile metals like aluminum because it is less corrosive than other soldering cores. You can also use it on brass and copper, where it doesn’t cause any unforeseen damage.

Its gentle nature also makes it the best bet for circuit board and electrical applications. Circuit boards are usually quite delicate and don’t need a soldering core that leaves corrosive residues.

Circuit boards have small delicate wires that would give anyone a hard time cleaning after soldering. With its penchant to no leave behind any flux residue, Rosin core is the most appealing core. That makes the best option when soldering circuit board components.

Its most prominent use, however, is in electrical appliances with wires that make delicate electrical connections. As we have mentioned before, such wires would require a lot of work to clean after soldering. That is why rosin solder core is the better option since it leaves no residue.

What is 60/40 rosin core solder?

60/40 Rosin core solder is a variant of Rosin core solder with 60% of tin and 40 percent of lead as the components. 60/40 rosin core has a low melting point which makes it the ideal core for fine electrical soldering.

Fine electrical soldering requires soldering cores with very low melting points to avoid damaging delicate parts. Lead-free solders are, however, more preferred because they are less toxic.

What is 60/40 rosin core solder

Advantages of rosin core solder

Rosin core solder is a popular soldering option for many reasons. Firstly, it doesn’t leave any solder flux residue behind. Therefore, you will save yourself a lot of time using it as you don’t have to clean up afterward.

Thanks to its ability to leave no residue, it is ideal for delicate wiring on circuit boards. That’s because cleaning such wires after attaching them to the board might be a complicated affair. That’s why you would need a core solder that doesn’t leave flux residues.

Rosin core solder has a low melting point which makes it a convenient soldering material. That makes it an ideal alternative to the high melting point core solders that can’t be used for fine soldering. The whole point of soldering is to glue components onto a surface to sustain damage.

Additionally, rosin core doesn’t have corrosive soldering flux. This point, however, is moot considering that it won’t leave any residues.  Still, some variants might leave behind slight residues, and it would help if they were noncorrosive.

On the downside,

however, it has a narrow range of metals and metal alloys it can work with. It is best for copper and brass components with little success in other metals or alloys.

Acid core vs rosin core solder: which is better?

There are very many different soldering cores, of which rosin core is one of them. But have you ever heard of the acid core?

The acid core is primarily solder made into a wire form that has a hole as its core. The hole is then filled with acid-base flux making up what is known as the acid core flux. The hollow core is usually filled with flux. There are different types of fluxes you can use to do that.

It is a highly aggressive core mainly used in plumbing applications as it links sheet metals and metal pipes. That’s possible since it creates strong bonding between components, making it harder for water to leak through pipes. Acid core flux is also more corrosive than rosin solder core which explains why you can’t use it as you would rosin.

Whereas acid core solder has high acidity, the rosin core consists of only mild flux. The acidity makes the acid core a rather versatile core that you can use on stronger metals of different varieties.

Besides being the best for plumbing, Acid cores are also ideal for use in the automotive industry, metal works, and aerospace engineering. By it being acidic, it gets rid of any oxides that might form on soldering, therefore helping to create a stronger bond.

The acid core is also an excellent option if you are soldering metals that have tiny diameters. That’s because it thoroughly cleans surfaces enabling you to avoid the metal from losing any of its diameter to impurities.

The major downside to using acid core is that you will have to clean up the residues after soldering. That and the fact that is it is pretty corrosive makes it unsuitable for specific applications such as soldering of electronic components.

You also can’t use it on fragile metals such as aluminum. The acid core’s acidity will eat right through the relatively softer aluminum metal rendering your work useless. If you are predominantly working with aluminum, then rosin core solder will be the best option.

Compared to Rosin core solder, it is more versatile and will work on almost any metal save for aluminum. The residues acid cores have make the rosin core a better alternative.

You will have seen some applications that each of the two types of core solders is good at. Therefore, choosing which one to go for lies with you because they all have qualities, you would want in a soldering core.

Where to buy rosin core solder?

You’ve heard all there is to hear about rosin core and might have made up your mind to get some. But where do you get it?

Getting rosin core solder isn’t that hard. There are a ton of retailers on the web that sell rosin core solders and others as well.

Amazon is an excellent place to start if you are looking for the best rosin core solder, for starters. Joom is also another option you can choose if you want to buy some rosin core solder.

You, however, don’t have to restrict yourself to online retailers alone since most electronics stores should have a variety of soldering wires, including rosin core. Just remember to make sure it is the exact product you’re looking for.

How to tell if solder is rosin core?

You might know all there’s about buying rosin core, but how do you tell that you bought the right one? If you are to get a suitable rosin core, you will need to identify it from other nondescript materials.

Here is how you can do that.

The nature of rosin itself will guide you in distinguishing it from other cores. Firstly, it is usually a lot thinner than other cores. You will also notice a more pleasant smell when you burn it. That isn’t the same for the other soldering cores.

Heated rosin core also leaves a tiny grease stain on the surface you burnt it. To test it, you can burn it on a clear piece of paper and observe the stain. 

It would help if you also took note of the smoke as it usually is light.

That’s how to differentiate it from the other cores, including acid cores. Don’t rely on your eyes alone to distinguish it from other cores since they are usually quite similar.

Frequently Asked Questions (FAQs)

Q. What temperature does rosin core solder melt?

Ans: Like most other solders, Rosin core solder has a melting temperature of between 90o and 450o Celsius.

Q. Does rosin core solder have lead?

Ans: Yes, 60/40 rosin core solder contains 40 percent of lead.

Q. Can rosin core solder be used for plumbing?

Although rosin core solder has a variety of applications, the best option for plumbing is acid core. Acid core has all the properties that would make it an ideal plumbing flux.

Q. Do I need a separate flux if I’m using rosin flux core solder?

Ans: You don’t need extra flux if you are using rosin core solder. That’s because the rosin itself acts as the flux negating the need for any additional flux.

Q. Can I use rosin core solder for stained glass?

Ans: No. Rosin core solder isn’t a good option for stained glass since it could give you a hard time cleaning up the mess you will create. For stained glass, solid core solder is an excellent option.


Soldering is an essential part of the manufacturing process since it helps make better metal connections by creating solder joints on circuit components.

Knowing the best solder to use for each application is essential if you are to save yourself many headaches. Rosin core solder is a crucial type of core solder with crucial applications. We hope you now know enough about it to use it efficiently. 

Related: How to Practice Soldering? (Step by Step Guide)


  • https://www.amazon.com/Alpha-AT-31604-60-40-Solder-Ounces/dp/B00030AP48?th=1
  • https://electronics.stackexchange.com/questions/128960/what-sort-of-soldering-iron-tip-do-i-need-for-very-fine-pcb-work
  • https://info.mayeralloys.com/blog/acid-core-solder-and-its-uses
  • https://weldingmastermind.com/how-to-tell-if-solder-is-rosin-core-heres-how/
  • https://www.build-electronic-circuits.com/right-soldering-temperature/
  • https://www.quora.com/Can-I-use-a-rosin-core-solder-for-stained-glass

Brandon M. Fox

I have completed Diploma at Welding. I have spent 10+ years in Welding. Now love to write about welding and welding products and share my own experiences. Find me: Twitter | Facebook