Everything You Need to Know About Welding Engineers Chalk

One of the most demanding professions when it comes to hands-on experience, as well as the most in-demand jobs right now is considered to be welding. This fabrication process involves being near a spark generating torch which you need to control in order to join two metal pieces together. While it might sound dangerous, it’s quite safe when done properly.

There are different welding processes. As long as you have the right equipment and gear, you’ll be good no matter which type of welding process you go for. But there is one piece of essential welding equipment that not everyone seems to appreciate as much as some other gear. I’m talking about engineer chalk, which is crucial for making precise cuts.

What Is Engineers Chalk Used For?

Generally speaking, engineer chalk is mainly used in the marking of metal and steel. This way, you can leave a clear wax-like mark that can withstand the rigours of metalwork. Quality engineers chalk or French chalk, as it’s also known, is easily the best way to mark cuts.

Engineers Chalk
Source: toolking.com.au

Why Do Welders Use Chalk?

The same reason why anybody else would use an engineers welding chalk – to mark the area they want to cut or separate from a workpiece.

What Is Engineering Chalk Made From?

Engineers chalk is made from a naturally soft rock that derives from the mineral talc called soapstone. Soapstone is nothing new, as it has been used for thousands of years. When formed into a piece of chalk, soapstone allows you to write and mark extremely well on various materials such as stone, slate, metal, and bricks.

Benefits of Soapstone


The most notable advantage soapstone offers that no other marking tool does is heat retention and resistance. This allows you to write on hot metal without the markings going away. This is thanks to the Magnesite which is the main compound found in soapstone and is responsible for its ability to absorb, radiate, and retain heat.


Another thing that soapstone has great resistance against is acid. Even if you work with a shielding gas, it won’t get rid of the marks on your workpiece. You can try and spill lemon juice and the soapstone marks won’t go away. However, you shouldn’t try and use hydrochloric acid.


Soapstone is known as being extremely dense despite being soft. This is what makes it resistant to staining. The talc in soapstone is hydrophobic, meaning it can repel water. This dense formation of the small talc minerals will make your soapstone markings indestructible. The only way you can erase soapstone markings is to cut the workpiece they’re on or polish it.

Source: en.wikipedia.org

Other Uses of Engineers Chalk in Welding


Even before you start to weld a metal workpiece, you will notice that it comes with markings. What do you think these markings are made with? You guessed it – welding chalk. These tags and markings are usually done with either a pen or clear soapstone, and suppliers use them daily.


One of the things about soapstone or engineer chalk is that you can file it down to the thickness you need for your markings. When you want to make precise cuts on small and narrow workpieces, it can save you a lot of time. You will have a better fitting workpiece so you’ll be able to join it together at a later stage.

Flame Straightening

When a weld gets distorted from too much stress, you use an oxyacetylene torch to bring the material into shape. But before you do so, you need to use soapstone to make the necessary markings so that the workpiece is brought back correctly. In this case, you should just mark the dimensions of the weld path with no more than 1cm on either side of the weld toes. The weld path is then switched up with the other side of the joint and is traced using the welding soapstone chalk. This way, you will straighten up the flame that causes the weld with the help of a line made by a simple piece of chalk, and avoid more serious issues later down the line – no pun intended.

Flame Straightening
Source: oerlikon-welding.com


Welding, as we know, is an inevitable process when it comes to making big or small metal or steel structures. Sometimes it can be used to weld wood, but these are rare cases. No matter what you’re welding, and which process you’re relying on for the weld, soapstone or welding chalk is almost always going to be needed, and every true welder will tell you that even the smallest deviations can make or break a project. So, take notice of what the pros do, and make sure you always have soapstone ready to be used in your workshop, to clearly mark where you’ll need to join or cut the metal pieces you’re working with.