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Starch Ether — Open Time Extender for Tile Adhesive | GCC

CAS No: 9049-76-7 · HS Code: 3505.20

Starch Ether (pre-gelatinised hydroxypropyl starch, CAS 9049-76-7) is a dry-mix mortar additive primarily used to extend open time and improve workability in tile adhesives and related cementitious products. 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.

Quick Specifications

CAS Number9049-76-7
HS Code3505.20
CAS Number9049-76-7 (hydroxypropyl starch)
Chemical TypePre-gelatinised hydroxypropyl starch ether
AppearanceWhite to cream free-flowing powder
Moisture Content≤ 12.0 %

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Technical Specifications

PARAMETER SPECIFICATION TEST METHOD
CAS Number9049-76-7 (hydroxypropyl starch)
Chemical TypePre-gelatinised hydroxypropyl starch ether
AppearanceWhite to cream free-flowing powderVisual
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 aloneEN 1346
Degree of Substitution (MS)0.05 – 0.20
Typical Addition Level0.1 – 0.5% on dry mix weight
Shelf Life12 months in sealed bags, < 30°C, < 70% RH

Applications — UAE, Saudi Arabia & GCC

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. Used in combination with HPMC for optimised water retention + open time balance.

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.

Usage & 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 Available

25 Kgs Multi-Wall Paper Bags
500 Kgs Supersacks

Storage & 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.

Need TDS or SDS Documentation?

Full Certificate of Analysis (COA), Safety Data Sheet (SDS/MSDS), and Technical Data Sheet (TDS) supplied with every shipment from Dubai or Riyadh.

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Frequently Asked Questions

Tile adhesive failures in GCC summer are predominantly caused by premature skinning — the adhesive surface dries before the tile is pressed into it, resulting in zero-bond adhesion (you can pull the tile off cleanly after setting). The root causes are: ambient temperatures 40–50°C, substrate temperatures 50–70°C on sun-exposed concrete or screeds, and low relative humidity 15–30%. Starch ether combined with HPMC delays the skin-over of the adhesive surface by slowing water migration to the surface. This extends the open time from 5–10 min (standard adhesive) to 20–30 min (HPMC + starch ether modified C2TE), giving the tiler adequate time to place and adjust tiles. For extreme GCC summer conditions, use C2TE classified adhesive and advise application in early morning or shaded conditions.