Hydrofluoric Acid

Hydrofluoric acid (HF) is an inorganic acid that exhibits several chemical and toxicological properties which make it highly hazardous to work with. HF is not a strong acid, yet is corrosive and strongly reacts with glasses and metals. Upon contact with skin, fluoride ions quickly penetrate skin and have the capacity to cause deep tissue damage. At high concentrations symptoms will immediately occur, but at low concentrations symptoms may not be evident for hours. Without treatment, tissue damage can continue to worsen for several days. Concentrated HF also produces irritating, corrosive vapors which may cause severe health effects if inhaled.

General precautions

These precautions apply when using HF or working with chemicals or processes which may generate HF:

  1. When HF is present in a laboratory, all laboratory personnel should be informed of the dangers associated with HF and appropriate emergency response procedures.
  2. Only experienced personnel should handle gases or concentrated solutions of HF (>1%)
  3. Never use HF when working alone or after hours.
  4. Conduct operations in a properly functioning chemical fume hood with current EH&S certification.
  5. In laboratories where HF is used routinely, emergency procedures and SDS should be clearly posted adjacent to the work area.
  6. A HF spill kit should be located adjacent to the work area. In addition to typical spill kit materials, the kit should include calcium gluconate gel (2.5%), calcium gluconate (1% in normal, sterile, saline solution), and calcium gluconate (5% in normal, sterile, saline solution). These solutions should be replaced annually and labelled with a new expiration date.
  7. All HF spills should be reported to EHS. If the spill is large or concentrated, contain the spill using HF specific absorbents if it can be done safely, grab SDS and emergency procedures, evacuate the area, and call 911. Avoid vapor exposure. Top priority is to preserve human life.
  8. Avoid treating HF spills with the following: sodium or potassium carbonate, sodium of potassium hydroxide, silicon-based absorbents.

Emergency Response

The following actions should be taken when HF exposure is suspected. Dilute exposures of HF may not exhibit symptoms for several hours and in these cases treatment should still occur as swiftly as possible.

Be mindful of secondary contamination during first aid. When possible, the victims should perform first aid action on themselves. Regardless of who is providing aid, appropriate gloves should be donned. Latex does not provide an effective barrier against HF.

In all instances, take note of the concentration of the acid, time of exposure, means of exposure, methods of treatment, and the area and location of exposure. Provide this information to EHS and to medical personnel.

Skin Exposure.

First priority is to flush the area with water. Quickly move to and activate the emergency shower and remove all contaminated clothing and that which could trap HF. The acid should be rinsed as thoroughly and quickly as possible. If calcium gluconate gel (2.5%) is available, rinse for 5 minutes and begin to liberally and continually apply the gel. The area does not need to be dried. If not, continue to rinse for 15 minutes or until medical treatment is available.

While the victim is rinsing, someone should call 911 and inform them that someone has been exposed to HF, the location of the individual, and request an ambulance.

Once emergency personnel have been contacted and rinsing/gel application has begun, re-examine the victim for potentially overlooked sites of exposure.

Eye Exposure.

Immediately flush eyes with flowing water at an eyewash station. Hold eye lids open and away from the surface of the eyes. If sterile, 1% calcium gluconate solution is available, begin to drip continuously into the eyes within the first 5 minutes. Do not use more concentrated calcium gluconate in the eyes. If solution is not available, flush eyes for 15 minutes.

While the victim is rinsing, someone should call 911 and inform them that someone has been exposed to HF, the location of the individual, and request an ambulance. If possible, see an eye specialist. Irrigate eye during transportation.


Immediately remove victim to fresh air and call 911. Keep victim warm, comfortable, and quiet. If breathing has stopped, check airway for obstruction and administer CPR. 100% oxygen should be administered as soon as possible by a trained individual and continue until medical personnel arrive. 2.5% calcium gluconate solution may be nebulized and administered to the victim. IF vapor exposure has caused burns, these should be treated the same as liquid HF exposures.


Do not induce vomiting. Have the victim drink large amounts of room temperature water or milk as soon as possible. If available, Tums, Milk of Magnesia and other antacid products may be effective at neutralizing the effect of the acid. Do not administer bicarbonates as the carbon dioxide byproduct may cause additional injury.

The victim should be admitted to the hospital for treatment.

Preparation of Calcium Gluconate Gel

  1. Heat a measured amount of K-Y Jelly (Johnson & Johnson) to 50-60 degrees C, typically 395 grams.
  2. Add 2.5% by weight (9.9g) of reagent grade calcium gluconate slowly with good stirring until all dissolved.
  3. An alternate method of adding the calcium gluconate is to add 2 grams and stir in until mostly dissolved, then add the remaining calcium gluconate (added to 35 cc of H20) with good stirring until dissolved into the jelly.
  4. Finished gel will be water-clear with many air bubbles which can be removed by allowing the bubbles to rise to the surface after standing.