What Is Gel Blocking?
Direct Answer
Gel blocking happens when surface SAP granules swell so fast they form a gel barrier that stops liquid reaching the dry core below, causing pooling and leaks.
Key Takeaways
- Gel blocking happens when surface SAP granules swell so fast they form a gel barrier that stops liquid reaching the dry core below, causing pooling and leaks.
- How it works: When the top layer of SAP absorbs and swells faster than liquid can pass, the swollen gel seals the surface.
- Low-SFC SAP can gel-block, leaving the diaper surface wet while the core stays dry
- Myth: More SAP is always better. Poor SAP distribution or low SFC causes gel blocking that hurts performance
How Gel Blocking Works
When the top layer of SAP absorbs and swells faster than liquid can pass, the swollen gel seals the surface. Liquid pools on top instead of reaching dry SAP underneath, reducing total absorbency and increasing leakage risk. Prevention: balanced SAP particle distribution, high SFC (saline flow conductivity) SAP, and mixing with fluff pulp for channels.
Examples and Applications
- Low-SFC SAP can gel-block, leaving the diaper surface wet while the core stays dry
- Modern cores blend high-SFC SAP with fluff to keep liquid channels open (BASF)
Gel Blocking vs. Related Terms
| Term | What it is | Key difference |
|---|---|---|
| Core clumping | Gel Blocking | Gel blocking is surface SAP swelling blocking inflow; clumping is internal structure breaking into lumps |
Limitations and Common Misconceptions
- Myth: More SAP is always better. Poor SAP distribution or low SFC causes gel blocking that hurts performance
- Myth: Gel blocking means the diaper is full. The core may be dry — the gel wall is blocking further absorption
What causes gel blocking?
Surface SAP swelling too fast and sealing the surface, stopping liquid from reaching dry core below.
How do manufacturers prevent gel blocking?
Using high-SFC SAP, good particle distribution and fluff channels that keep liquid flowing.
References
- BASF - Superabsorbents (HySorb / SAVIVA), how SAP works — BASF (accessed 2026-08-02)
- Family Cares - The Science of Absorbency: Superabsorbent Polymer in Diapers — 行业媒体 (accessed 2026-08-02)