The core criteria for determining if color-changing silica gel is fully regenerated are complete color recovery, dry and loose granules without clumping, and timely sealing after cooling to prevent secondary moisture absorption.
1. Color Recovery: The Most Direct Judgment Standard
Blue Silica Gel: Should completely change from pink/red to deep blue, with uniform color and no grayish-white, dark red, or localized black areas;
Orange Silica Gel: Should completely recover from dark green/green to bright orange, without turbidity or mottled appearance;
Key Note: If the color recovery is incomplete after heating, it indicates aging, contamination, or insufficient regeneration temperature.
Turn the granules under natural light to ensure consistent color change and avoid misjudgment due to localized incomplete dehydration.
2. Physical State: Dryness and Structural Integrity
Indicators Complete Regeneration Performance
Touch: Dry, non-sticky, no dampness
Particle State: Loose, freely rolling, no clumping or softening
Integrity: Hard particles, no obvious powdering or cracking
If clumping, greasiness, or powdering occurs, it indicates contamination or structural damage, making complete regeneration impossible.
3. Functional Verification: Actual Moisture Absorption Capacity Test
(1) Sealed Humid Environment Test
Operation: Place the cooled silica gel into a sealed food storage box containing a damp towel and let it stand for 24 hours;
Judgment:
Slow and uniform color change → Successful regeneration, normal function;
No color change or rapid complete color change → Micropore blockage or failure, incomplete regeneration.
(2) Moisture Retention Capacity Test
Procedure: Place in a sealed box with a camera, medicine, etc. for one week;
Judgment:
No color change → Still has moisture-proof ability, regeneration is effective;
Color change within a short period of time → Insufficient adsorption capacity, needs to be regenerated or replaced.
