What are the pros and cons of using steel gage blocks? Steel is the classic choice when it comes to deciding on a base material for your gage blocks. Steel has a distinctly hard surface and is therefore resistant to chipping or cracking. Additionally, this hard material will be protected during lapping and ideal for wringing. Another major advantage of steel gage blocks is that most industrial parts that will need to be gaged will also be made of steel. Therefore, steel gage blocks will very easily match the thermal expansion coefficient of the material being measured. The greatest disadvantage of steel as a gage block material is that it is not stable over time. While advances have been made, steel will expand over time due to the crystal makeup as well as the hardening process. Furthermore, steel is subject to corrosion caused by scratching or humidity and will likely rust over time. Steel gage blocks can be the ideal choice in a shop environment and are built strong depending on what you need for precision measurement.