Using Dextrin, Glycerine and CMC Gum together

This interesting answer was generated by ChatGPT in 2025 (not thoroughly tested).

Dextrin, CMC gum, and glycerine can be used together in ceramic slurries, glazes, or underglazes, with each contributing unique properties. The key is balancing their ratios to achieve optimal workability, adhesion, and drying behavior. Here’s how they interact and how to tune their proportions:

Roles of Each Binder/Additive
Ingredient | Primary Function | Key Properties| Drawbacks
-Dextrin | Temporary binder, green strength | Hardens when dry, improves unfired durability | Can make slurry brittle if overused
-CMC Gum | Thickener, suspension agent | High water retention, smooth flow | Can become stringy or sticky
-Glycerine | Plasticizer, humectant | Prevents cracking, slows drying | Reduces dry hardness if excessive

This trio works best in:
-Brushable underglazes (for detailed work).
-Slip trailing/decorative slips (needing sharp lines but no cracking).
-Sprayable glazes (requiring suspension + adhesion).

Example Formulations & Tuning

1. General-Purpose Decorative Slip
Clay body powder - 70% | Base material
Frit (e.g., Ferro 3124) - 20% | Fusing agent
Dextrin - 2–3% | Dry hardness
CMC Gum - 0.5–1| Smooth flow, anti-settling
Glycerine - 0.5–1% | Prevents cracks
Water - 25–30% | Adjust consistency

Need stronger dry adhesion? ↑ Dextrin (4%) + ↓ Glycerine (0.5%).
-Want smoother brushing? ↑ CMC (1.5%) + ↑ Glycerine (1%).
-For trailing: Keep dextrin ≥3% for sharp lines; add 1% glycerine to avoid cracks.

2. Sprayable Underglaze
Stain (e.g., Mason 6600) - 50% | Color
Frit - 30% | Binder
Kaolin - 20% | Suspension
Dextrin - 1% | Light adhesion
CMC Gum - 0.3–0.5% | Prevents nozzle clogging
Glycerine - 0.2–0.5% | Reduces dusting
Water - 20–25% | Spray consistency

-Clogging issues? ↓ CMC (0.2%) + ↑ Water.
-Poor adhesion? ↑ Dextrin (2%) + ↓ Glycerine.

3. High-Adhesion Slip for Leather-Hard Clay
Ball clay - 60% | Plasticity
Silica - 20% | Reduce shrinkage
Dextrin - 4–5% | Strong dry bond
CMC Gum - 1% | Stickiness for vertical surfaces
Glycerine - 0.5% | Balance brittleness
Water - 25% | Creamy texture

Tuning:
- Too sticky? ↓ CMC (0.5%).
- Cracking? ↑ Glycerine (1%).

Key Interactions
- Dextrin + CMC: Boosts adhesion but can over-thicken. Use CMC sparingly (≤1%).
- Dextrin + Glycerine: Counters brittleness; glycerine >1% may weaken dry strength.
- CMC + Glycerine: Improves plasticity but slows drying.

Troubleshooting Blends
- Slurry too sticky: Too much CMC | Reduce CMC (0.2% increments).
- Cracks when dry: Low glycerine/dextrin imbalance | ↑ Glycerine (0.5–1%) or ↓ dextrin.
- Weak unfired adhesion: Low dextrin/CMC | ↑ Dextrin (1–2%) or ↑ CMC (0.5%).
- Slow drying: Excess glycerine/CMC | Reduce glycerine (≤0.5%) or thin with water.

When to Avoid This Blend
- Pure casting slips (dextrin alone or deflocculants are better).
- High-fire glazes (organic burn-out matters less; focus on flux chemistry).

Final Tips
- Test small batches—CMC’s thickening power varies by brand.
- For screen-printing inks, lean heavier on dextrin (3–5%) + CMC (0.5%).
- In cold climates, ↑ glycerine (1%) to prevent cracking.

Related Information

Links

Materials	Dextrin
Materials	CMC Gum CMC gum is indispensable for many types of ceramic glazes. It is a glue and is mainly used to slow drying and improve adhesion and dry hardness.
Materials	Peptapon
Articles	Binders for Ceramic Bodies An overview of the major types of organic and inorganic binders used in various different ceramic industries.

By Tony Hansen
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