High performance mould and core coatings for the elimination of surface defects providing superior casting finish – Foseco

The foundry industry encompasses many metal types and production processes, producing an array of cast components in a multitude of different sizes. To acknowledge this diversity, Foseco have developed a variety of coating ranges to ensure that product and process are optimised. These include:

A range of water-based coatings with superior dipping properties, designed specifically to meet the demanding requirements of the production iron foundry.


Semco and Teno
Semco water-based and Teno solvent based coatings are available in a full range of application rheologies and refractory combinations to offer superior performance to individual foundry requirements.

Specialist coatings for
Lost foam and full mould processes
Spun pipe production
The enhancement of metallurgical properties
The protection of refractories and metal tools

All Foseco products are supported by a team of technical experts who can advise and help you to develop optimised coating practices.

The high casting temperatures associated with steel foundries requires careful selection of refractory materials, to ensure full protection against metal penetration and burn-on defects. The Semco and Teno range of coatings for steel applications utilise high purity zirconium silicate refractories to offer protection under the most extreme casting conditions.


A full range of specialist products is also available to cover specific applications, such as the high demands of manganese steel, highly alloyed stainless steels or metal penetration due to hot spots or high metallostatic pressures.

These products are formulated to ensure rheology is optimised for specific application methods.

Jobbing iron
This segment of the market is typified by the variety of size and shape of cast components, ranging from many tons to less than a kilogram. The processing of such components in short runs requires flexible manufacturing techniques. This variety and flexibility is reflected within the coating product ranges on offer from Foseco.

The Semco and Teno product ranges utilise precise blends of refractory fillers to ensure ultimate protection of both mould and core. In the case of heavy sectioned castings a combination of high purity zirconium silicate and graphitic fillers provide optimum refractoriness and prevention of metal penetration, whilst maintaining a good strip and reducing “white shining”. As section thickness is reduced, alternative fillers such as alumino silicates can be introduced to improve insulation properties and help to eliminate sand expansion defects, whilst maintaining excellent strip and casting surface finish. A full range of specialist products is also available to cover specific applications, such as prevention of flake reversion in ductile iron.


All these products are formulated to ensure rheology is optimised for specific application methods.

Production iron
High production foundries with a large proportion of cored castings, typify this segment. The production unit is typically highly automated and the application of coating is normally via a dipping operation. The Rheotec, Semco and Teno range of coatings are focused on providing exceptional dipping characteristics, whilst ensuring internal surfaces are free from casting defects.

Refractory filler combinations are carefully selected and controlled and rheological properties are designed to apply a controlled coating layer. Specific coatings are available to offer superb protection against a number of common defects.

An example of this is Rheotec XL, which offers unparalleled protection against the formation of veining defects.

Metallurgical coatings
A full range of specialist products is also available to cover specific applications, such as localised chill and grain refinement. Tellurit chill-promoting coatings for grey cast iron are ideal for producing a wear resistant surface.


Molco 50 dressings are designed for the localised densening of grey cast iron. They can eliminate the use of metal chills and are useful for treating heat centres affected by open grain structure that are difficult to feed.

Full mould and lost foam processes
Semco perm is a range of water based coatings designed to promote excellent surface finish and dimensional stability whilst avoiding common problems such as lustrous carbon formation, metal penetration and premature mould collapse.

Permeability and composition have been specifically designed to meet the requirements of lost foam. The coatings can be applied by spray, dipping or brush.

Spun pipe
Spuncote are specialist products formulated to provide a permeable coating with very low gas evolution for the centrifugal casting process. They can also assist metal flow and promote easier stripping of the finished casting.

Tools and refractories
Fracton coatings are used for the protection of refractory surfaces, metal dies and launders, pig moulds and other metal tools.

Foseco offer a wide range of equipment for the handling and application of refractory coatings, ranging from containers and mixer units to spray equipment, flow coating units as well as automated application control systems.


Flow coating
Pioneers in the development of flow coating technology, Foseco’s Flow Coating Unit is specifically designed to meet the needs of the foundry such as consistent, operator independent application of the coating, even coverage of all mould surfaces including vertical walls and deep pockets, reduced mould abrasion and subsequent sand and refractory inclusions, absence of unsightly brush or swab marks and the enhancement of finer detail such as numbering and lettering.

A refractory coating provides a protective barrier between the molten metal and the mould or core substrate during the casting process, and ensures the integrity of the as cast surface.

Defect prevention
Through the use of carefully selected refractory fillers, Foseco coatings are designed to deposit the correct coating structure onto a given substrate, to ensure cast surface integrity and help in the reduction and elimination of a number of casting defects such as metal penetration, poor casting strip, mould erosion, gas defects, metal/mould reactions, sand expansion defects, metallurgical defects and scabbing defects.

To deposit a consistent layer of coating, which is free of runs, drips and other discontinuities, products have been developed with specific rheological properties to suit a wide range of application methods including dipping, flow coating, brushing and spraying.

The thickness of the coating layer, when dry, should be sufficient to supply the required protection. Within a production environment it is recommended that dry layer thickness is related to wet layer – film thickness comb, viscosity – flow cup and baumé – baumé stick.

For more information contact Foseco on TEL: 011 903 9500 or visit www.foseco.com