Flow-coating is a very efficient method, which is frequently used for applying wet enamels on e.g. cookware & water tanks. Continue reading “Flow-coating systems”
Enamel slip properties
The consistent liquid enamel slip properties is a critical parameter at any automated wet application process.
Unfortunately enamel rheology is known to change easily under the influence of particle size, specific weight, temperature, milling additives and/or pretreatment chemicals.
Failure to maintain its properties within measurable tolerances, may result in inconsistent enamel layer thickness and eventually even enamel defects.
Do you really believe that you can “feel it” with your fingers as demonstrated on the picture below, or do you rather prefer a more precise testing method ?!
Steam spraying improves application
Visited the Tecnargilla 2018 show in Rimini some weeks ago and saw there a new application method called “Steam Spraying”.
Continue reading “Steam spraying improves application”
Wet enamel application
Porcelain enamel may be applied via a variety of wet application methods, such as dipping, flow-coating, slushing and spraying. Continue reading “Wet enamel application”
Typical mill additions to enamels and their function
| Mill addition | Function |
| Aerosil | Set-up |
| Aluminium oxide | Matting agent and to increase heat resistance of ground coat |
| Aluminium hydroxide | Equivalent to aluminium oxide |
| Aluminium powder | Increase heat resistance in ground coat |
| Antimony trioxide | Increase adherence of ground coat |
| Barium chloride | Set-up in cover coat |
| Barium carbonate | Set-up in cover coat |
| Bentonite | Set-up |
| Borax | Set-up in ground coat |
| Boric acid | Set-up |
| Cadmium oxide | Stabilize Cd-Se red enamels |
| Clay | Provide bubble structure |
| Cupric chloride | Self lustre enamel 1118 |
| EK-1000 | For continuous clean enamel |
| Feldspar | For ground coat |
| Gumst | Increase filmstrength |
| Magnesium chloride | Set-up cover coat |
| Magnesium nitrate | to increase suspension and to prevent fishscales |
| Opacifier UV | Opacifier |
| Potash | Set-up |
| Potassium choride | Set-up cover coat |
| Potassium nitrate | Oxidizing agent for aluminium enamels |
| Quartz | to increase firing range and matting agent |
| Silicic acid | Set-up |
| Silver sand | For heat resistant ground coat |
| Soda ash | Set-up in ground coat |
| Sodium aluminate | Set-up in cover coat |
| Sodium nitrite | Set-up in ground coat |
| Sodium pyrophosphate | To decrease set-up |
| Sodium silico fluoride | Set-up cover coat |
| Tinoxide | Opacifier |
| Titanium dioxide | Opacifier |
| Trisodium phosphate | To prevent rusting in cast iron ground coat |
| Urea | To prevent hairlines in cover coat |
| Zirconite | Opacifier |
| Zircon oxide | Opacifier |
Wet enamel preparation & milling
Prior to the actual application, porcelain enamel slip need to be prepared in accordance with the application requirements, such as fineness, set and specific gravity.
The traditional wet enamel preparation process (“milling”) consists of the following seven sequential steps :
- weighting of various frits & additions in accordance with the milling formulation
- loading ball mills
- adding water
- wet milling
- discharging ball mills
- sieving & magnetic screening of slip
- storage