ALU-STOP LC25 Boron-Nitride-Coating is suitable for coating thimbles, transition plates and the refractory lining of the distribution trough of Wagstaff™ Casting Systems. The very good non-wetting property of ALU-STOP LC25 Boron-Nitride-Coating makes an easy and effective removing of remaining melts possible. It is a proven replacement for graphocote (both based on xylene and water) when applied on thimbles and transition plates. Used on the distribution trough it replaces coatings like terracote and those based on bone ash.
ALU-STOP LC25 Boron-Nitride-Coating is a water-based paste-like products and should be diluted with distilled water prior to use. Best performance of ALU-STOP LC25 Boron-Nitride-Coatings achieved by applying thin coats of 50-100µm (2-4 mils).
In the following examples the application of ALU-STOP LC25 Boron-Nitride-Coating is described on Thimbles as well as on Transition Plates and on the refractory lining of the distribution trough.
Application to Thimbles
When a new table is put into service with new thimbles (usually made of fused silica) the inner surface is being coated at room temperature using a soft brush. A mixture of 1 part ALU-STOP LC25 and 2-3 parts water give best results. Coating should air dry before heating up table to casting temperature.
During casting breaks the is being tilted upward araund 90° . Now the remaining metal is easily removed because ALU-STOP LC25 is an effective release agent. Each casting break should be used to brush the inner surface of the thimbles when being hot by using a mixture of 1 part ALU-STOP LC25 and 3-5 parts water. It is important to apply thin coats because thick coats may crack during use and do not show any technical advantages.
Application to Transition Plates
Transition plates (usually of Ca-Silicate) may be coated by brushing using a mixture or 1 part LC25 and 2-3 parts water. However, it is important not to coat the porous graphite die because this could interrupt gas flow.
Application on the Refractory Lining of the Distribution Trough
After a new refractory lining is installed and coated with the sealer, ALU-STOP LC25 Boron-Nitride-Coating is brushed onto the could surface using a mixture of 3 parts LC25 and 4 parts of water. A whole table will be covered by about 750g of ready to use mixture (=320g ALU-STOP LC25).
During each casting break ALU-STOP LC25 Boron-Nitride-Coating may be applied on hot surface after removal of aluminium by using a spray gun. Best mixture will be 1 part ALU-STOP LC25 and 4 parts water. A consumption of 575g of the ready-to-use mixture has been observed (=115g ALU-STOP LC25, about 6-8g ALU-STOP LC25/t casting).
Remark: Caused by thermal stress the refractory lining of the distribution trough shrinks during use forming cracks of a width of 0.5-2mm. Because ALU-STOP LC25 Boron-Nitride-Coating is applied in thin coats those cracks will not be covered. Therefore, these cracks must be filled in time by using a suitable repair putty. Otherwise liquid aluminium will fill these cracks causing adherence to the lining.
ALU-STOP LC25 Boron-Nitride-Coating must be protected against frost. A storage temperature of >5°C (>41°F) is recommended. The containers should be kept closed. ALU-STOP LC25 Boron-Nitride-Coating is available in 6kg-containers.
white or coloured
Solid Content (Boron Nitride)
Temperature (max. Application)
1000°C (at air)
1800°C (under inert gas)
© 2023 Büro für angewandte Mineralogie · Dr. Stephan Rudolph · D-47918 Tönisvorst
These recommendations are believed to be correct. However, no guarantee of their accuracy is given. Therefore, purchasers shall make their own tests to determine suitability for their use. These products are offered for industrial and related uses (e.g. research and development) only. However the user must take the necessary precautions appropriate for products containing chemicals. This description does not imply the absence of any patents, the responsibility whatsoever solely rests with the user.