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.
Originally application of porcelain enamel was done manually, as shown at the pictures below.
With increasing labor cost and production volumes, manual application was replaced by automatic application. In order to reduce enameling cost and/or improve the coating quality, more advanced applications systems, such as electrostatic wet spraying, robot spraying and electrophoresis, where introduced in the 50’s and 60’s.
Nowadays wet enamel is typically used for small production runs (of special colors), special enamels and/or when the product design isn’t suitable for electrostatic dry application.
Well-know liquid enamel application equipment producers include : Binks, Devilbiss, ECCO, EIC, Eisenmann, Fisher, Sames, VGT.
DTC may assist you to evaluate, which application method and/or equipment is most suitable for your products, and if required also help you with sourcing / procuring the appropriate machines.
Related topics :
- Wet enamel preparation
- Enamel slip testing
- Enamel consumption calculation
- Transfer efficiency & material utilization calculation
- Pumps for enamel slip
- Powder 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