About Alcohol-based Foundry Coating Rheology Modifier
This alcohol-based foundry coating rheology modifier develops a stable gel structure in alcohol carriers such as ethanol and isopropanol, keeping refractory fillers suspended in fast-drying mould and core coatings. It is intended for foundries and coating producers that use ignited or air-dried alcohol washes, particularly on cores and moulds where water must be kept away from the sand.
Alcohol behaves differently from water. Clay minerals that gel readily in water often give little structure in alcohol, so a coating built on them can settle hard and apply unevenly. This grade is formulated to build viscosity in alcohol systems, providing yield value at rest and shear-thinning during dipping, flow-coating, brushing or spraying. Because alcohol coatings dry quickly, often by ignition, the coating must level within seconds; a well-balanced rheology helps the layer even out before it sets, reducing drips, curtains and thickness variation at edges.
The modifier is designed to re-disperse readily when a coating is stirred after storage, while leaving the refractory character of the coating uncompromised. Obsidian Minerals supplies it from Gujarat as powder or as a pre-gel dispersion, tested in an NABL-accredited laboratory. Samples are available so you can evaluate it with your own filler, binder resin and alcohol blend.
Typical specifications
| Parameter | Typical Value | Test Method |
|---|---|---|
| Appearance | Light-coloured, fine powder | Visual |
| Moisture (105 °C) | ≤ 4.0 % | Internal method |
| Dry residue on 75 µm sieve | ≤ 5.0 % | Internal method |
| Compatible carriers | Ethanol, isopropanol and their blends | — |
| Gel behaviour in alcohol | Reported on TDS | Internal method |
| Recommended addition | 0.5–2.5 % of total coating weight | — |
Typical values for guidance. Guaranteed limits are stated on the Technical Data Sheet and batch CoA. Activation guidance for alcohol systems is given on the TDS.
Key features & benefits
Structure in alcohol carriers
The alcohol-based foundry coating rheology modifier builds a gel network in ethanol and isopropanol, giving suspension power in carriers where water-gelling clays are largely ineffective.
Levelling before ignition
Shear-thinning flow lets the coating spread and level in the short time before it is ignited or flashed off, helping to produce an even refractory layer on cores and moulds.
Supports water-free coating
By making alcohol-borne washes practical, the grade lets foundries coat moisture-sensitive cores and moulds without introducing water, which can weaken some chemically bonded sands and their binder systems.
Soft, re-dispersible sediment
Any sediment that forms during storage remains soft and is typically brought back into suspension by stirring, so coating density can be restored quickly at the start of a shift.
Ready-to-use pre-gel option
A pre-gel dispersion avoids the high-shear activation that powders can need in alcohol, shortening batch preparation and making it easier to keep successive batches consistent.
Applications
Ignited core washes
Suspension control in alcohol-based zircon and graphite washes applied to chemically bonded cores and then ignited, a common route for cores that must be used soon after coating.
Mould coatings for large castings
Rheology support for alcohol coatings sprayed or brushed onto large moulds for steel and iron castings, where even film build across big surfaces is difficult to achieve.
Alcohol coating concentrates
Helps coating manufacturers formulate alcohol-based concentrates that stay stable in drums and dilute uniformly with alcohol at the foundry to the working density or Baumé.
Usage & handling
- Typical addition is 0.5–2.5 % of total coating weight, adjusted to filler density and target viscosity.
- Disperse powder into the alcohol under high shear before adding fillers, following the activation guidance on the TDS; the pre-gel can be blended in with moderate stirring.
- Work away from ignition sources when handling alcohol carriers, and follow the SDS for both the additive and the solvent.
- Store powder dry in sealed bags and keep pre-gel containers tightly closed.
Packaging & supply
- 25 kg or 50 kg HDPE or paper bags for powder
- 1 MT or 1.2 MT jumbo bags for powder
- Pre-gel packing and private-label options on request
Frequently asked questions
Why does a water-based suspending agent not work in alcohol coatings?
Many clay-based suspending agents depend on water to swell and build structure. In ethanol or isopropanol they swell very little, so viscosity and suspension are weak and fillers settle. The alcohol-based grade is formulated to develop structure in alcohol carriers, giving the yield value and shear-thinning behaviour that alcohol washes need.
How much alcohol-based rheology modifier is needed?
Typical additions are 0.5–2.5 % of total coating weight. Heavier fillers such as zircon and lower solids contents usually need more, while lighter graphite or mica coatings may need less. Start with the level suggested on the Technical Data Sheet and adjust using density or Baumé checks, settling tests and application trials on your own moulds or cores.
Can the alcohol-based grade be used with ethanol and isopropanol?
Yes. The grade is intended for ethanol, isopropanol and blends of the two, which are the usual carriers for ignited and fast-drying foundry coatings. Gel development can vary with the alcohol type, its water content and the resin binder, so confirm viscosity and suspension in a trial batch with your own solvent blend.
Is a pre-gel version of the alcohol-based grade available?
Yes. Alongside the powder, a pre-gel dispersion can be supplied, which removes the need for high-shear activation at your plant and makes batch preparation quicker and more repeatable. Packing options and handling guidance for the pre-gel are confirmed on request, together with the Technical Data Sheet and MSDS/SDS.
Can the alcohol-based grade be adapted to my coating?
Custom grades can be developed with customers where a standard grade does not give the required suspension, levelling or drying behaviour. Share your filler system, binder resin, alcohol blend, application method and the problem you want to solve, and we will propose a trial plan and send samples for evaluation.