Using a resuscitation mannequin for the headform, the ocular area was covered with a white blotting paper (180 mm × 100 mm) dipped in 0.1 mol/L of sodium carbonate and dried. A phenolphthalein solution was prepared as per the standard. A hand atomiser was sprayed at a rate of 28‐30 mL/minute 600 mm from the headform in all directions within the frontal hemisphere but not extending beyond the ears over 10 seconds. If the reagent penetrated the FS, a crimson coloration will develop on the treated blotting paper.