Expert: John Franceschini - 4/7/2010

Question
Hi John,
Years ago i work at a hospital in the kitchen that used a tank of sodium hydroxide solution to soak oven racks overnight and the burnt stuff came right off in the morning.  Do you know the typical concentration of this solution and can i soak the black metal piece (feels in heavy iron) on top of a gas range in this stuff.  it's the metal rack that you actuaaly put the pot or pan on over the burner.  Thanks

Answer
It was probably a 3 to 5% solution i.e 3grams per 100 ml water.

Try this and if it doesnt work then increase the level of sodium hydroxide slightly.

However- be warned- sodium hydroxide soltuions are extremely alkaline and will seriously burn on contact with skin eyes etc....- the handling of this needs to be done very carefully- wear full protective gear whilst handling- gloves, goggles, skin cover and shoes- do not spill!!!!!