We have developed many release agents over the last 30 years. Each one is compatible with a particular substrate and a particular material poured onto it.
Release agents may be painted, sprayed or smeared onto the substrate.Their efficiency depends on how smooth the substrate is.
If there are undercuts, nothing will work. If the substrate or the poured material are slightly flexible, stripping is greatly facilitated.
Instead of writing a book, I am only going to deal with release agents for molten metal.
Aluminium Non-Wetting Paint paint is supplied as a thick paste, smearable. It can be diluted and used as a paint, or further diluted and sprayed on. The most important application is smoothing over aluminium launders etc. to prevent frozen aluminium sticking and doing serious damage to refractory during cleaning. It can extend refractory life ten times! It is used as a die coating where dies are imperfect, with light undercuts.
Graphite Die Coating is sprayed very thin onto casting dies, with negligible loss of detail. Graphite Paint is thicker.
Boron Nitride is the Rolls Royce of release agents. Normally used very thin on very smooth surfaces. Too expensive to use on rough refractory castings.
Keracoat Al is the next best. Imported. Silver colour. Development no. 119001
Mouldwash is a cheap material for covering over the large defects of the substrate.
High Temperature Batt Wash was developed for ceramics, but it is now more widely used on sensitive alloys.
Ceria Mould Wash Wash is similar, but the original materials are no longer available, and it has become very expensive.
We are currently developing Anode Mould Wash for copper and matte.
Aluminium Non-Wetting Paint
Uses: Covering of all surfaces which come into contact with molten aluminium. It prevents adhesion of aluminium to all surfaces and prevents reaction of the molten metal with refractory linings. It prevents pick-up of iron etc. by the aluminium. It allows easy cleaning of ladles, launders and holding furnaces etc.
Description: The paint is supplied wet in plastic buckets, ready for use. The colour is blue when applied, and turns white after heating. It can be painted on with a brush or swab. It is chemically inert, harmless, non-irritant and non-flammable. It contains water as the only solvent. Clean the surface to remove loose particles and dust before painting.
Graphite Die Coating
A concentrated suspension of fire graphite in water. Used as a lubricant and release agent in die-casting.
Dilute as required, between 1:5 and 1:2
It is a black creamy paste with a pH of 9 to 9,5 and a density of 1,2 to 1,24 g/cm³
Contains no toxins.
Shelf life: Several years
Development no. 39719
Boron nitride has a plate like structure similar to graphite. (Another form of boron nitride has a diamond-like structure and is used for cutting tools).
It is a super smooth lubricant with extreme non-wetting properties towards molten aluminium. We use it on our aluminium dosing pumps, and others use it on Kerasic die casting moulds.
The maximum service temperature is 900°C.
It is very expensive, but only a few grams are required to give lubrication or non-wetting.
It is supplied as a water based suspension, and can be diluted with water before application by brush or spraying.
Mouldwash 18301 is an aluminosilicate scull release coating for hot metal ladles. It is supplied dry, and can be mixed with water to make a wash, and good suspension properties. It is lime free, graphite free, phosphate free, harmless and non-toxic. It has low alkali content and has no fluxing action on alumino-silicate refractories.
Mouldwash 18301 will not withstand the abrasion of a direct stream of metal.
Packaging 20kg thick transparent polythene bags
High Temperature Batt Wash
Conventional batt washes adhere to batts if fired above 1100ºC, and need to be replenished after each firing. The build up later cracks off, leaving an irregular surface.
High temperature batt wash does not sinter at all, even under an oxy-acetylene flame. It does not need replacement until it has been physically rubbed off. A thin coating will prevent surfaces from sticking after firing. This is very useful when levelling props with clay, or for painting onto the mating surfaces of pot lids etc. It is also used on contact surfaces of doors and dampers when repairing kilns with Fibre Plaster. (Ask for kiln repair instructions.)
Mixing: 75 parts powder to 25 parts water. It is based on ziconia, which tends to settle out due to its extremely high density.
Turbulence in gas fired kilns may spread batt wash onto glaze.
If batts are turned over, clean all batt wash off the underside.
Ceria Mould Wash
Ceria Mould Wash is based on three stable oxides with very high melting points; Ceria, CeO₂ (Cerium oxide) 2700°C.
Alumina, Al₂O₃ (Aluminium oxide) 2015°C, and Zirconia, ZrO₂ (Zirconium oxide) 2700°C.
All three are very stable and not reduced by molten metals.
No compounds are formed between these three oxides, and therefore they have little tendency to sinter.
Modified versions are available with better suspension properties and or adhesion properties.
Ceria Mould Wash will remain powder at high temperature and after cooling.
Composition; Al₂O₃ 80,5% Fe₂O₃ 0,4%
ZrO₂ 4% CeO₂ 15%
SiO₂ 0,06% CaO 0,1%
Application; Mix with water, (about plus 50%), pour through a sieve finer than the spray nozzle and spray onto mould. It forms a stable suspension even at +70% water. No chemicals should be added.
-1mm +106µm 10%
-106 +75µm 6%
Packaging: 15kg plastic bags stretch wrapped on pallets.
Shelf life: Indefinite.
Development no: 41704