Doming (coating)
Doming is a description for a process for the production of a curved, decorative, three-dimensional surface coating (doming coating of a surface), which usually has a glass, highly transparent look. This doming coating can be used to effectively reinforce the aesthetic effect of plotted lettering or print motifs on polyester, PVC and metallic foils as well as on metal and plastic moldings. Usually doming in combination with a self-adhesive substrate is also referred to as a gel sticker or 3D sticker. For the preparation of doming coatings are resins based on polyurethanes or isocyanatfreiem used material. While doming coatings with polyurethane are air-drying, isocyanate-free doming resins cure under UV light . Isocyanate-free materials differ again in the number of components, which in BioDome only consists of one and can therefore be processed directly and without waiting time and preparation.
Comparison of doming resins
| Isocyanate-free doming | Doming with polyurethane | |
|---|---|---|
| Hardening | light-curing, quick in minutes | air-drying, adjustable setting time, from a few minutes to several hours, ideally in temperature-controlled rooms |
| handling | very long pot life, little technological effort for mixing and dosing technology | very short pot life (minutes) two-component system can be processed both by hand and by means of dosing systems ( pay attention to economic efficiency) after mixing the components absolutely non-toxic and can be disposed of as "normal waste" due to a lower surface tension of the material very good flow properties degree of hardness Coating variable (gel-like to rubber-like) |
| Stresses during handling | non-toxic components, harmless to humans - but can also lead to skin irritation, no hazardous goods, harmless in storage and transport | toxic components low mercury content , but there are also systems without mercury. The main components are isocyanates , risk of skin irritation |
| disposal | no ecological pollution normal commercial waste disposal |
no ecological pollution can be disposed of as "normal waste" in the fully reacted state |
| economics | low investment and ancillary costs | Basic investment in machine processing, no investment in manual processing, lower material costs, economical for large quantities |
The advantages of both resin systems are high flexibility and hard elasticity, broad application possibilities, high transparency, three-dimensional optical effect, very good adhesive properties, long composite service life as well as UV and climatic stability and thus suitability for outdoor use.
Advantages of doming stickers
Stickers coated with doming have advantages over normal stickers. The doming coating provides stickers with effective protection. This gives the stickers shock, scratch, UV and weather resistance. However, there are differences in weather resistance. Air-dried polyurethane stickers have a lower UV resistance than gel stickers that are dried in UV ovens. These doming stickers are usually significantly more expensive.
Manufacture of doming stickers
Doming stickers are made in two steps. In the first step, the sticker to be finished is printed. Printing with solvent-based inks requires a drying time. In the second step, the gel (doming) is applied to the sticker. This can be done with a dosing device or a robot. Due to the high viscosity , the gel flows to the edge of the sticker and stops. Then the freshly cast doming stickers can be placed in a UV light oven. The resin has hardened after approx. 8 minutes. If doming material without UV technology is used, the drying process takes several hours. During this time the surface is extremely sensitive to dust.
