How to determine if color-changing silica gel has been activated after cooling?
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The main criterion for judging if the colour changing silica gel has been activated after cooling is whether the colour has returned to the initial dry colour. For example blue silica gel should be uniformly deep blue, and orange silica gel should return to vivid orange, and it should be securely packaged and stored after cooling.
1. Colour Restoration: Direct Evidence for Activation
Blue silica gel (cobalt chloride): After complete regeneration and cooling it should be a consistent deep blue, free from reddish, greyish or mottled tints.
* Orange silica gel (cobalt-free, environmental friendly): It must turn brilliant orange again and the dark green colour that developed when it failed must be fully gone.
Key Note: The indicator's colour mirrors the state it is in. Colour restoration = effective activation = normal indicator function.
2. Auxiliary Judgements Techniques
Materials and Methods
Directions for use
Basis of Judgement
Surface Inspection
Squeeze the particles gently.
Loose, no lumps → Structure intact; Hardened or powdery → Possibly overheated damaged.
Seal Test
Place in a clear zip lock bag. Set aside for 1 hour.
No fogging, no discolouration → No moisture absorption, activity is good.
Environmental Exposure Testing
"Put it in a sealed container with some humidity for twenty-four hours.
Slowly transition from blue to pink → Normal moisture absorption function, turned on.
Failure of regeneration and incomplete activation are indicated by the fact that the colour does not return after heating (e.g. grayish-white, dark red).
3. Preventive actions
The cooling process should be done in a dry environment: it is best to cool naturally in the oven with the power off, so that the airflow does not introduce moisture.
Do not seal late. Seal within 5 minutes after cooling, so that the new restored dryness capacity is not cancelled by ambient humidity.
Count the number of regenerations: Even if the colour recovers after more than 5 regenerations, the adsorption capacity may decline. Effectiveness needs to be evaluated in conjunction with the usage scenario.
In practice, the triple guarantees for validating the activation are "full colour restoration + stability after cooling + timely sealing".
