In GCC construction environments — where intense heat, direct sunlight, and low humidity cause rapid drying of wet mortar before tiles can be placed and adjusted — starch ether is the critical additive that extends the workable open time from 5–10 minutes (unmodified) to 20–30 minutes (starch ether + HPMC modified), enabling professional tile installation.
Technical specifications
| PARAMETER | SPECIFICATION | TEST METHOD |
|---|---|---|
| CAS Number | 9049-76-7 (hydroxypropyl starch) | — |
| Chemical Type | Pre-gelatinised hydroxypropyl starch ether | — |
| Appearance | White to cream free-flowing powder | Visual |
| Moisture Content | ≤ 12.0 % | Karl Fischer |
| pH (2% solution) | 6.5 – 8.5 | — |
| Viscosity (2%, Brookfield) | 200 – 800 mPa·s (grade dependent) | — |
| Open Time Extension | +5 – +15 min vs HPMC alone | EN 1346 |
| Degree of Substitution (MS) | 0.05 – 0.20 | — |
| Typical Addition Level | 0.1 – 0.5% on dry mix weight | — |
| Shelf Life | 12 months in sealed bags, < 30°C, < 70% RH | — |
| HS Code | 3505.20 |
Applications
- Tile Adhesive Open Time Extension — The primary GCC application. Starch ether extends the open time of C2TE tile adhesives to meet the EN 1346 requirement of ≥ 30 minutes — allowing tilers working in GCC ambient conditions to place and adjust large-format porcelain tiles.
- Renders & Machine-Applied Plaster — Improves workability and reduces stickiness of machine-applied renders — critical for the high-volume render application on GCC residential and commercial building facades.
- Self-Levelling Underlayments — Extends flow time and working window of self-levelling compounds — gives GCC applicators adequate time to spread and debox the compound before it begins to set.
- EIFS Base Coat Mortars — Improves spreadability and extends workability of EIFS base coat mortars applied by hand or machine on polystyrene insulation boards.
- Tile Grouts — Small addition improves workability and reduces grout drying speed, particularly in hot, direct-sun GCC exterior joint filling applications.
Key properties
- Extends open time by 5–15 minutes vs HPMC-only systems
- Improves workability and slip resistance of fresh mortar
- Reduces stickiness on trowel and substrate
- Works synergistically with HPMC — use in combination for best results
- Low addition level required (0.1–0.5%) — cost-effective
- Non-ionic — compatible with cement, gypsum, and all standard additives
- Improves anti-sagging of adhesive on vertical surfaces
- GCC climate benefit: compensates for rapid moisture loss in hot conditions
Usage and recommendations
Use in combination with HPMC, not as a replacement. Typical formula: HPMC 0.2–0.3% + Starch Ether 0.1–0.3% on dry mix weight. Starch ether alone (without HPMC) does not provide adequate water retention. In GCC summer conditions (40–50°C ambient), increase starch ether addition to the higher end of range (0.3–0.5%) and advise applicators to apply adhesive in shaded areas where possible. Starch ether has a lower heat tolerance than HPMC — avoid adding to hot batches (> 60°C mixing water). Contact Raykem for formulation optimisation for your specific GCC tile adhesive class target.
Packaging
- 25 kg Multi-Wall Paper Bags
- 500 kg Supersacks
Storage and shelf life
Store in sealed bags below 30°C with relative humidity below 70%. More moisture-sensitive than HPMC — ensure proper sealing and covered storage in GCC coastal warehouses. Shelf life: 12 months.