High Performance Specialty Chemicals & Services Contact Us

Nitric Acid/Hydrofluoric Acid Mixtures

Click image to enlarge

Hydrofluoric acid/nitric acid mixture is clear liquid with an acidic odor. The mixture is made in different concentrations and used to prepare the surface of implantable medical devices for the application of bioactive coatings. Implantable devices are often made from titanium, stainless steel or Nitinol (NiTi) and must be etched to improve the surface texture for proper coating adhesion. Achieving 100 percent adhesion of bioactive coatings is imperative, as this is what allows the device to properly attach to bone or living tissue and prevent the body from rejecting an implant.

  • To the best of our knowledge, this product is California Prop 65 compliant.

Mixtures containing Hydrofluoric acid and nitric acid are used to clean and etch the surface of various implantable medical devices including:

  • Stents
  • Bone plates
  • Dental implants
  • Pins and screws
  • Rods and bars
  • Spinal fusion cages

Request a quote for off-the-shelf hydrofluoric acid and nitric acid mixtures or contact us to learn more about custom ratios.

Hydrofluoric and Nitric Acid Mixtures for Etching Titanium and Other Alloys

Hydrofluoric acid and nitric acid mixtures are highly effective at etching titanium, Nitinol, and stainless steel. Mixtures containing 3% hydrofluoric acid are the most common ratio used, and etch rates increase as the nitric acid concentration increases. 
Etching titanium with hydrofluoric acid alone is a slow process and produces a by-product of hydrogen gas. Adding nitric acid increases the etching rate, eliminates the formation of hydrogen gas, and produces a smoother surface finish. Without the nitric acid present, the titanium surface is very rough and nodular. As the nitric acid concentration increases, the surface roughness decreases to the point of creating a slight electro-polished surface that is almost reflective.

Etching Titanium and Dental Implants

Etching titanium with HF and nitric acid blends produces hexafluorotitanic acid, nitrogen dioxide, and water. With this solution, the HF tends to be more stable, the hydrogen gas is eliminated, and the etch rate increases. We offer different chemical concentrations of N+HF blends based on the required specification or on the desired effects of on the etch rate and surface finishes.

Achieving the Desired Thickness for Etching Titanium

Select a ratio based on your material type, shape, and surface. The higher the ratio of nitric acid, the higher the etching rate. Etching rates can also vary depending on the fluid temperature and material being processed.
Examples of typical etching rates for titanium:
  • Mixtures containing 3% hydrofluoric acid and 3% nitric acid provides an approximate etching rate of 8.92µ (0.351 mils) per minute.
  • A mixture of 3% hydrofluoric acid and 10% nitric acid provides an approximate etching rate of 24.51µ (0.97 mils) per minute.
  • Mixtures with 3% hydrofluoric acid and 15% nitric acid provide an approximate etching rate of 27.08µ (1.07 mils) per minute.
Medical device manufacturers often require a specific hydrofluoric acid and nitric acid mixtures based on what the FDA approved during the prototype and testing stage. All our chemical mixtures are made to order and available in off-the-shelf concentrations or in custom ratios based on your requirements. Hydrofluoric acid and nitric acid mixtures are offered in 4L (1 gal.) and 20L (5 gal.) plastic containers. We also provide 220L (55 gal.) drums fitted with color-coded drip tubes that easily connect to existing equipment.

Important Safety Precautions for Using Hydrofluoric Acid and Nitric Acid Mixture

The caustic nature of hydrofluoric acid and nitric acid mixtures poses a serious health risk to anyone who works with the solution. Inhaling the vapors can cause a sore throat, coughing, breathing issues, and lung inflammation or congestion. Skin contact causes severe burns. If the solution penetrates the skin, it can cause deep tissue and bone damage. Eye contact may also cause severe burns or permanent eye damage.
Symptoms of HF exposure are often delayed for several hours.  If you suspect you may have been exposed to HF contained in the Nitric and HF Blends but are not experiencing any immediate symptoms, apply immediate first aid, nonetheless.  A quick response can substantially reduce injury.
Prevent injury by taking these precautions whenever you work with hydrofluoric acid and nitric acid mixtures:
  1. Preparation: Read and fully understand the Safety Data Sheet (SDS) for hydrofluoric acid and nitric acid blends. Next, review or create a Standard Operating procedure (SOP) for the process where you are using the solution. Finally, obtain a Calgonate first aid kit and spill kit.
  2. Create a Designated Area: Nitric and HF B