Tinning flux vs. Paste flux: Advantage & Disadvantage Discussed

In the welding process, the filling agent and base metals melt to form joints. Thus, during and after weld creation, there is a huge potential for the molten weld to form oxides, nitrides, or sulfides over the surface due to the presence of various gases in the air. If it happens then, these impurities diminish the resistance of weld against corrosion. Thus, the welds will not be strong and stable.

That is why it is necessary to cope with the environmental contamination of welds to achieve a sustainable project. MIG welding is the most popular and easiest welding process that uses inert shielding gases to protect joints. However, various tasks require other welding techniques that do not use shielding gases to protect the welds. That’s why flux is there for this purpose.

Generally, a welding flux is an ingredient that protects welds from oxidation by forming a layer on top when the procedure begins. In this way, the welding flux prevents the weld from coming into contact with the air, protecting it from corrosion. Besides, various welding fluxes are available in the market that you can buy as per the metal type you have to weld.

Two of the essential welding fluxes accessible are tanning flux and paste flux. They have similar mechanisms but have a lot of disparities as well. Further, tinning flux is excellent for use in pipe welding; that’s why plumbers prefer it. Similarly, some people use paste flux for other applications due to its different characteristics than tanning flux. In this segment, we will learn tinning flux vs. paste flux, so carry on reading.

Here is a comparison:


Tinning Flux

A usually tinning flux has a greasy texture, and its color is greenish-gray. Moreover, the paste comprises particular flux metals, tin, ammonium chloride, bismuth, and copper. However, this paste sometimes constitutes lead for certain applications.

There are various uses of tinning flux, but you can solder some important metals, including iron, zinc, brass, and copper. Besides, it can easily clean the surface of metals to avoid corrosion and doesn’t pile up its residue. Additionally, this flux acts as an obstacle between joints and air, thus preventing environmental contamination.

Tinning flux isn’t water-soluble so, you can only clean it with a non-water solution, which makes it worse for use in electronic circuit board soldering. Also, you can not apply tinning flux for soldering aluminum, magnesium, and stainless steel. The use of this flux over these metals will not work. Therefore, it can not give you desired results.


The greasy texture of tinning flux makes it ideal for use on large pipes because a small quantity is sufficient for use on larger surfaces. Moreover, this quality saves time; that’s why plumbers prefer this flux over others in the market. It is also effortless to use on pipes due to its thick texture, which doesn’t slip, unlike juicy fluxes.

It wipes better than regular fluxes available in the market, which enables you to clean it easily after you are done. However, applying an adequate amount of tinning flux is the key to ideal soldering, so don’t be a miser when putting it over base metals. More than 700° Celsius temperature is indispensable to burn tinning flux; that’s why it can bear ultimate heat.


Despite its eye-catching advantages, it has some drawbacks as well, like any other flux type. The use of tinning flux is not cost-effective due to the high price. Therefore, it is not ideal for professional plumbers in that sense because they have to use tinning flux frequently.

Another thing that is lacking in tinning flux is a higher shelf life which is just one year from the manufacturing date. Moreover, this shelf life is less than all other commercial fluxes in the market. If you are looking to buy it and aren’t going to use it frequently, you will waste your money. We suggest you buy this flux in bulk if you have its frequent use to save money.

Related: Top Flux core welder

Paste Flux

Generally, paste flux is a type of flux that is usually available in the form of yellowish texture. All the ingredients in this flux are similar to thinning flux other than surfactant mixes, additional fillers, and triethanolamine HCL. Similar to tinning flux, you can apply it when soldering copper and its alloys.

Moreover, its use is beneficial for fire sprinklers and drinkable water pipes. However, you can use it on electronic circuit boards, aluminum, stainless steel, and magnesium. In addition to this, paste flux is chemically inert at temperatures ranging from 15 to 30° Celcius.

But when the temperature increases while heating the base metals, it will become chemically inert. Moreover, the percentage of active ingredients in paste flux is more than liquid flux. Paste fluxes have a maximum of 60 to 80 percent active components, while liquid has 2 to 25 percent.

What are common types of paste flux?

There are dozens of paste flux types available in the market, but we will discuss just three commons among them.

Water-soluble Flux

Water-soluble fluxes are made up of glycol because of their incredible cleaning and oxides removal capability. It tends to erode joints; it is not appropriately cleaned due to its high cleansing and oxidizing properties. Therefore, you need to wipe it off entirely to avoid oxides over the surface of joints.

Rosin Paste Flux

You can use rosin paste flux due to its mild property, which enables you to create smooth and neat joints effortlessly. That’s why it is less corrosive than water-soluble flux. Therefore, rosin paste solder is preferable for soldering circuit boards because it doesn’t demand after-process cleanup.

No-clean Flux

As from the name, it is clear that no clean flux does not require you to wipe it off after soldering or welding. Moreover, it is nonreactive and less corrosive, just like rosin paste flux. It is ideal for soldering those metals that are easier to solder.

What are the benefits of paste flux?

In welding or soldering, the most important thing is to hold the base metals correctly while performing the task. But paste flux has sticky property, which can help you shortly join two metals before welding or soldering. In this way, you will produce smoother and even joints.

Moreover, it is a form of thick texture that’s why ideal for you to apply it from unorthodox angles and places. Like tanning flux, it also acts as a barricade between the weld and the air. So, you don’t need to worry about corrosion and oxidation if you have to weld those metals that are prone to environmental contamination.

What are the disadvantages of paste flux?

As paste flux is of many types and they have their different composition, that’s why not all these types are beneficial for all projects. Moreover, you need to buy the right one for your task because all these are meant for a specific job, so pick the approximate one for your project.

Moreover, some paste flux categories include rosin juice as an ingredient that releases toxic smoke when heated. Therefore, you have to wear safety equipment when executing your project because it saves you from unwanted incidents. Besides, you can wear just a mask to cope with harmful fumes to a considerable extent.

After reading the article on tinning flux vs. paste flux ( comparison), we hope you can decide for yourself which one is better.

Also check: Homemade soldering flux