In industrial ceramic manufacturing, the "rotten egg" smell emanating from a slip tank is often dismissed as a mere nuisance. In reality, it is a critical process alarm. It signifies active anaerobic fermentation.

Many modern high-performance Ceramic Deflocculants (especially Sodium Humates and certain Polyacrylates) rely on organic backbones. When bacteria proliferate in your slurry, they do not just produce odor; they actively consume the chemical architecture of your dispersant. This degradation leads to rheological drift, gas-generated pinholes, and black coring defects that only appear after the kiln firing.

This technical directive outlines the mechanism of biological attack on rheology modifiers and the engineering controls required to sterilize the process.

1. The Problem: Rheological Drift & Gas Defects

The Consequence of Bio-Activity

When biological contaminants degrade the deflocculant, two catastrophic failures occur in the B2B production line:

1. Viscosity Instability: Operators report that slip viscosity increases overnight despite no changes in solids content. The bacteria are severing the polymer chains responsible for dispersion.
2. Micro-Gas Entrapment: The metabolic byproduct of bacteria is gas (Methane, Hydrogen Sulfide, CO₂). These micro-bubbles become trapped in the cast wall. Upon firing, they burst, creating Pinholes or react with iron in the body to form Black Coring.

2. The Root Cause: Enzymatic Hydrolysis

Bacteria vs. Polymer Chains

To solve this, we must understand the interaction between the microbes and the Ceramic Deflocculant.

Bacteria (such as Desulfovibrio or Bacillus spp.) secrete enzymes to break down complex organic molecules into simple sugars for food.
High-end deflocculants function via Electrosteric Stabilization—long polymer chains that wrap around the clay particle to provide physical spacing.

• The Attack: Bacterial enzymes target the carbon bonds in the deflocculant's polymer chain.
• The Result: The long chains are cut into short, non-functional segments. The "Steric Barrier" collapses.
• The Failure: Without the physical barrier, Van der Waals forces take over, causing the clay to flocculate (thicken) and the specific gravity/viscosity relationship to decouple.

3. The Solution: The "Clean-Kill" Biocide Protocol

Restoring Sterile Rheology

You cannot reverse bacterial degradation, but you can prevent it. The solution requires a multi-stage Hygiene Protocol.

4. Case Study: The Summer Stench Crisis

Saving the Sanitaryware Line

The Context: A sanitaryware factory in Southeast Asia (Avg Temp 32°C). They utilized a "Black Slip" containing organic lignites and a Sodium Humate deflocculant.

The Incident: Every Monday morning, the slip tanks smelled of rotten eggs ($H_2S$). The Monday production run consistently suffered from Glaze Crawling and Pinholing. The viscosity was consistently too high, forcing operators to add water (lowering Specific Gravity).

The Intervention:

1. Shock Treatment: We dosed the contaminated tanks with 0.2% Dazomet to kill active anaerobic bacteria immediately.
2. Process Change: Installed an automated dosing pump to inject BIT biocide into the raw water feed line.
3. Rheology Reset: With the bacteria dead, we reduced the Humate deflocculant dosage by 10%, as it was no longer being consumed by microbes.

The Result:

• Odor elimination within 24 hours.
• Pinhole defects reduced by 80%.
• Slip viscosity remained stable over the weekend shutdown.