Question

I am a non-chemist looking for some advice! I am an archaeologist and am currently using moisture-indicating silica gel (orange) to dry out some metal finds from our excavations. I have reheated silica gel before but I am looking for a refresher as it is many years I've done it!

I intend to heat a small amount at a high temperature (can anyone advise what temperature?) in an oven that is used solely for this purpose. How long do I need to heat it for? If I heat it for longer, is it likely to retain its colour for longer?

Additionally, how well ventilated does the space I am in need to be? I intend to wear gloves and a light-weight mask.

Answer 1

To regenerate silica gel, heat it between 100°C to 120°C for 1 to 2 hours in a well-ventilated area, while wearing gloves and a mask for protection. The duration of heating will not affect the gel's ability to indicate moisture.

Step-by-step explanation:

To recharge moisture-indicating silica gel, which turns from orange to green when saturated with water, you should heat it in an oven at a temperature between 100°C to 120°C for about 1 to 2 hours. This temperature range is sufficient to remove the absorbed moisture without damaging the gel's indicating properties.

Heating the silica gel will not necessarily maintain its color for a longer duration; its ability to change color is based on the presence of absorbed water and is not influenced by heating duration, assuming heating is done correctly.

It's essential to ensure that the space is well-ventilated to allow for the escape of any moisture or fumes released during the process. It is a good idea to wear protective gloves to handle the hot containers and a light-weight mask to prevent the inhalation of any fine particles or fumes.