Invar Etchants

Invar is a nickel-iron alloy known for its low coefficient of thermal expansion, making it particularly useful in applications where dimensional stability in varying temperatures is critical. Chemical etching of Invar is a process used to create precise patterns, markings, or designs on Invar surfaces. This process is often employed in the aerospace, electronics, and precision engineering industries. Here’s a guide on commonly used methods for etching Invar and how to set important parameters for effective Invar etching:

Commonly Used Invar Etchants

  1. Nitric Acid (HNO3) and Hydrochloric Acid (HCl) Mixture


  • Aerospace: Invar is used in aerospace applications, and etching may be employed for quality control, surface treatment, and marking.
  • Electronics: Invar components in electronics may undergo etching for surface preparation and quality inspection.

Setting Parameters:

  • Concentration: The mixture of nitric acid and hydrochloric acid can vary in concentration depending on the specific etching requirements. Common concentrations range from 10% to 20% for nitric acid and 5% to 15% for hydrochloric acid.
  • Etching Time: The etching time varies based on the desired result and the thickness of the Invar, ranging from minutes to several minutes.
  • Temperature: The etching process is often performed at room temperature, but the specific temperature may vary depending on the application.

Setting Parameters in an Invar Etching Operation

For an effective Invar etching operation using the nitric acid and hydrochloric acid mixture as an example:


  • Mix the nitric acid and hydrochloric acid in the desired proportions for the specific etching task. Be precise and exercise caution as both acids can be hazardous.

Etching Time:

  • Determine the appropriate etching time based on the desired pattern or surface modification. Start with a short duration and adjust as needed.


  • Perform the etching at room temperature or the appropriate temperature for your specific application.


  • Prioritize safety when working with nitric acid and hydrochloric acid. Always wear appropriate personal protective equipment (PPE) such as gloves, safety goggles, and lab coats. Maintain a well-ventilated workspace with safety showers and eyewash stations.


  • Maintain proper ventilation to dissipate fumes and gases generated during the etching process. Use a fume hood if available.

Waste Disposal:

  • Dispose of used etchant solutions following local regulations, as nitric acid and hydrochloric acid waste can be hazardous. Proper handling and disposal are crucial.

If you have an Invar etching project that you need help with, please contact us