Whether you need to dry out damp shoes, keep vitamin capsules from becoming sticky or save the cell phone that fell in a puddle, silica gel comes to the rescue. Silica gel, an inert, crystalline substance with great capacity for absorbing moisture from the environment, is a reusable desiccant. Regeneration of the crystals can be accomplished in your home kitchen, with minimal effort. Within a few hours, your supply of silica gel can be restored to full functionality, saving you money again and again.
- Skill level:
Things you need
- Glass baking dish
- Airtight storage container
- Kitchen scale
Inspect the silica gel crystals to determine the type of silica gel you have. Silica gel may be moisture indicating (pale pink or dark green when saturated and requiring regeneration) or non-indicating (white).
Set the oven temperature to 121 degrees Celsius.
Use the kitchen scale to weigh the mass of the non-indicating white silica gel crystals. Weighing is not necessary for moisture-indicating crystals as the colour serves as an indication of dryness.
Spread a thin, even layer of silica gel in the baking dish.
Place the dish on the middle shelf in the oven. This ensures ample air flow around the dish, encouraging rapid drying.
Bake the silica gel for three hours.
Check the colour of the indicating silica gel. If the crystals have resumed their desiccated colour (dark blue or orange), remove the dish from the oven and cool on a rack until the gel is at a safe temperature to handle. Otherwise, continue to bake the crystals until the correct colour is achieved. Non-indicating crystals should be weighed once cool enough to handle, and returned to the oven for further baking if the mass has not decreased as a result of water loss.
Seal the silica gel in the airtight container.
Tips and warnings
- Regenerated silica gel should not be exposed to the atmosphere for longer than 15 minutes after removal from the oven.
- A fan may be used to accelerate cooling of the regenerated gel after it is removed from the oven.
- Blue silica gel (pink when saturated) can tolerate regeneration temperatures of up to 149 degrees Celsius if a faster drying time is required, but the higher temperatures will reduce the lifetime of the gel.
- Heating silica gel at temperatures higher than those indicated above may result in degradation of the crystals, evidenced by blackening or powdering of the gel.
- Silica gel sealed in sachets should be regenerated at approximately 93.3 degrees Celsius to prevent damage to the sachet material.
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- "Applied Thermal Engineering"; Effect of regeneration; K Chang, H Wang, T Chung; April 2004
- "Renewable Energy"; The regeneration of silica gel ; S. Pramuang and R.H.B. Exell; January 2007
- "Journal of Ceramic Processing Research"; 2D-sim of silica gel; C Jung, J Kim, S Yi; Vol 9(2) 2008
- Popular Mechanics: 8 Clever Uses for Silica Gel