About Water-based Foundry Coating Rheology Modifier
This water-based foundry coating rheology modifier is a mineral additive that hydrates in water to form a stable gel structure, keeping heavy refractory fillers suspended in water-borne mould and core coatings. It is designed for coating plants and foundries that prepare their own dips, flow-coats or spray coatings and need consistent density from the first mould of a shift to the last.
Many foundries choose water-based coatings to reduce solvent use, but water gives little natural support to dense fillers such as zircon flour. Without a suspension agent, solids settle in storage tanks and dipping baths, the coating thins at the top and thickens at the bottom, and the risk of veining, metal penetration and uneven surface finish rises. The modifier develops yield value at rest and shear-thins during application, so the coating flows, levels and drains evenly, then holds on vertical surfaces while the water is removed by drying.
The grade is designed for the pH range typical of water-based coatings, from 4 to 10, and to work alongside common organic binders, wetting agents and biocides, with compatibility confirmed in your own trials. After storage the coating can usually be returned to specification with normal stirring rather than heavy remixing. It is supplied as powder or as a pre-gel dispersion from our Gujarat plant.
Typical specifications
| Parameter | Typical Value | Test Method |
|---|---|---|
| Appearance | Light-coloured, free-flowing powder | Visual |
| Moisture (105 °C) | ≤ 12.0 % | Internal method |
| Dry residue on 75 µm sieve | ≤ 5.0 % | Internal method |
| pH (5 % aqueous dispersion) | 7.5–10.0 | Internal method |
| Effective pH range in coating | 4–10 | — |
| Gel viscosity (aqueous dispersion) | Reported on TDS | Internal method (Brookfield) |
| Recommended addition | 0.5–3.0 % of total coating weight | — |
Typical values for guidance. Guaranteed limits are stated on the Technical Data Sheet and batch CoA. Performance should be confirmed in the customer's own coating formulation.
Key features & benefits
Hard-settlement prevention
The water-based foundry coating rheology modifier forms a gel network that holds dense zircon and graphite fillers in suspension, limiting hard sediment in storage drums, tanks and dipping baths.
Shear-thinning application
Viscosity drops under the shear of stirring, pumping, spraying or dipping, then recovers at rest, so the coating levels smoothly and resists runs and sagging on vertical mould faces.
Designed for pH 4–10
The suspending effect is designed to hold across the pH range found in water-borne coatings, giving formulators latitude in their choice of binder, wetting agent and preservative.
Easy re-dispersion
Any sediment that forms stays soft and loosely packed, and can typically be brought back into suspension by normal stirring, reducing downtime and waste when coatings are stored between campaigns.
Powder or pre-gel supply
Powder suits plants with high-shear mixing; the pre-gel dispersion is ready to blend, shortening preparation time and reducing the risk of incompletely hydrated lumps in the finished coating.
Applications
Zircon-based mould and core coatings
Suspension control for zircon flour washes used on steel and heavy iron castings, where uniform coating thickness is important for resisting metal penetration and burn-on.
Graphite and carbon coatings
Anti-settling support for graphite-rich water-based coatings applied to grey and ductile iron moulds and cores, where consistent coating density helps maintain a smooth as-cast surface.
Silicate and mica coatings
Rheology control for aluminosilicate, talc and mica-based coatings used for non-ferrous and light-section iron castings, supporting even application by dip, flow-coat or spray and consistent layer thickness across the mould.
Coating concentrates
Helps coating manufacturers produce concentrated pastes that remain stable during storage and transport, then dilute evenly with water at the foundry to the working density specified by the casting process.
Usage & handling
- Typical addition is 0.5–3.0 % of total coating weight; optimise against filler type, solids content and application method.
- Disperse powder into water under high shear and allow full hydration before adding refractory fillers; the pre-gel can be added directly with moderate stirring.
- Check density (or Baumé) and viscosity after each addition and again before use.
- Store powder dry in sealed bags; protect the pre-gel from freezing and keep its containers closed.
- Follow the SDS for dust control during handling.
Packaging & supply
- Powder in 25 kg or 50 kg HDPE or paper bags
- Powder in 1 MT or 1.2 MT jumbo bags
- Pre-gel packing options confirmed on request
- Private-label packaging for coating manufacturers on request
Frequently asked questions
How much water-based rheology modifier should be added to a foundry coating?
Typical additions are 0.5–3.0 % of total coating weight. Coatings with dense zircon fillers or low viscosity at application often need the upper part of the range, while graphite or mica coatings may need less. Begin with the level suggested on the Technical Data Sheet, then fine-tune using settling tests, density checks and your application method.
Does the water-based grade need to be pre-gelled?
When supplied as powder, it should be dispersed in water under high shear and allowed to hydrate fully before fillers are added, which gives the strongest gel structure. Plants without high-shear mixing can use the pre-gel dispersion, which only needs moderate stirring into the coating. Both forms are available from the same grade.
Will the water-based grade work with my binder system?
It is designed to work alongside the organic binders, wetting agents and biocides commonly used in water-based foundry coatings, across a pH range of about 4 to 10. Because binder chemistry varies, compatibility and storage stability should be confirmed in a trial batch of your own coating before switching suspension agents in production.
How long will a water-based coating stay in suspension?
Suspension time depends on filler density and particle size, solids content, modifier dosage and storage temperature, so no single figure applies to every coating. The modifier is designed to slow settling and keep any sediment soft and easy to re-disperse. Run a standing settling test on your own formulation to set storage and stirring routines.
Can coatings containing this grade be sprayed?
Yes. Because the modifier is shear-thinning, viscosity falls in the spray nozzle and recovers once the coating reaches the mould, helping to build an even layer without runs. Spray performance also depends on solids content, nozzle size and pressure, so adjust dosage and dilution during trials on your own equipment.