"Our client approached us primarily because we are the only manufacturer of printed tiles that could produce the personalization required at an affordable price," said Christina Cantarini, the company's director. "Another issue was durability; our customer needed to be sure that the image on the printed tiles would not degrade when exposed to the chemicals and extremely humid conditions found in a swimming-pool environment. We were really excited when we heard about this job, because we felt that it would give us the perfect opportunity to show what our products could really do."
With a tile size of 20 x 20 cm (8 x 8 in.) covering an image area of 5.4 x 1.2 meters (approximately 18 x 4 feet), the swimming pool project would be the largest and most demanding personalized project that RGB had ever tackled. It was the brainchild of a local Italian engineer, who had gained his inspiration from Japan. In addition to being tiled with a personalized design, the pool would also incorporate a hydro-massage system, a wave machine and an air-conditioning unit to keep the ambient temperature cool while the pool temperature remained at a constant 30°C (86°F).
Because of the varying atmospheric temperatures, it was vital that the right tile and image production process be used-a process that would require a new decorating technology.
Then Cantarini heard about a new decorating technology called CromalinR Art. "When we saw the DuPont system, we knew our search was over. The system is based on the same technology as analog Cromalin, a leading color proofing system for the graphic arts industry, so it was the ideal solution for our needs. It produces consistent, non-degradable, low cost, photo-quality images every time," Cantarini added.
The original Cromalin color proofing system simulates four-color printing using a photopolymer technique to transfer the four basic printing ink colors to a receptor paper. Cromalin Art uses the same principle to apply four ceramic color pigments to a decal transfer paper. (See sidebar: The Cromalin Art Process.) The individual ceramic colors correspond to the film separations of the job, building up a final high-resolution, photo-ceramic image in less than 30 minutes.
Once the image is built up on the decal paper, it can be transferred to any ceramic surface, such as pottery, china, stoneware, or even glass, to create unique ceramic pieces, including decorative tiles, plates and glassware.
Like any other piece of ceramic ware, the item is fired in an oven at high temperature. This permanently fixes the colors to the surface, creating a very high-resolution image that is resistant to superficial abrasions, water damage and the effects of solvents. In fact, the colors are designed to last for decades.
The new process is suitable for even the most artistic designs, providing high definition, quality images. Its straightforward process allows full scope for the creativity of architects and interior designers and presents new opportunities for customizing walls and other large surfaces in swimming pools, bars, hotels, restaurants and other facilities.
"We were really impressed with how easy the DuPont system was to operate," said Cantarini. "The technology is incredibly user-friendly, which meant that we did not have to spend endless days training our staff to use the equipment. This was a real bonus, as time is critical in this business and can have a real impact on costs."
The technology can provide a real economic advantage, particularly in the creation of a single ceramic piece or for low-volume production. It is designed to produce fast, high quality images with long-term durability.
"We are really pleased with the new system, which is revolutionizing the ceramic and glass industry and opening up many new opportunities both for our customers and ourselves," said Cantarini. "We estimate that there are almost 10,000 new applications where we could apply the technology. Current projects include decorating glass for the furniture industry, murals for the decoration of public buildings and other areas where personalization, durability and cost-effectiveness are key issues.
"With our new system, we feel that we have taken an important step in the market for professional ceramic imaging and can now provide an unbeatable standard for Italian decorative ceramic and glass. This makes us confident of continued success in the future," Cantarini said.
Next, another layer of Cromalin film is then laminated on top of the pre-laminated paper. The color separation(s) for the first color (normally yellow) is positioned on the laminated paper and exposed in the UV exposure frame. The exposure should be chosen to hold 2 to 98% dots on a 60 lines per centimeter (150 lines per inch) screen. The Cromalin cover sheet is then removed, and yellow ceramic toner pigment is applied by hand-toning or with an automated toning machine (ATM) to create the yellow parts of the image. The excessive toner powder must be wiped away from the image with an anti-static cloth. To obtain reproducible results with both hand-toning and ATM, the room temperature should remain constant at 23°C I 2°C (approx. 70-80°F) and the relative humidity should remain constant at 40 to 60%.
After the first color is toned, another layer of Cromalin film is laminated on top of the first color (yellow). The separation for the second color (normally cyan) is then positioned in register to the first color and exposed in the UV frame. After the cover sheet is removed, the image is toned with the cyan ceramic toner pigment. The same procedure is repeated two more times using the color separations for magenta and black, as well as the corresponding ceramic toner pigments, to complete the four-color image. A final layer of Cromalin film is then laminated and exposed with the post-curing setting.
Color Sequence.The ceramic color pigments should be applied to the ceramic (and to the transfer paper) in the order of decreasing melting temperatures to prevent disturbance of the image during the melt process. Therefore, the recommended color sequence is yellow-cyan-magenta-black. In most cases, a cyan-yellow-magenta-black sequence also works well and can make the registration of the second to the first color easier.
Transferring the Image to the Product.Once the cover sheet of the last Cromalin layer has been removed, the image to be transferred is then cut out of the transfer paper and immersed in a bowl of plain tap water for approximately 1 to 3 minutes (depending on the type of transfer paper being used). When the image begins to separate from the carrier paper (i.e., the edges are lifting), the paper is taken out of the bowl (with the image still on top) and placed (paper down) on the ceramic or glass surface. The decorator then slides the image from the paper to the product's surface while simultaneously removing the paper to the side. The image can be carefully moved on the surface to position it accurately. The water between the image and the product's surface must be removed completely using a soft plastic squeegee or other similar device.
Firing Conditions.To set the image, the product is fired at temperatures defined according to the glazing process (on-glaze, in-glaze or under-glaze). During the firing process, the organic materials from the Cromalin film burn away without residues, leaving only the photo-quality art on the product's surface. To ensure defect free results, a controlled firing cycle should be used, especially in the temperature range of 200 to 400°C (392 to 752°F), which is when the Cromalin film decomposes.
Cycle times of less than four hours have been used successfully in different types of ovens. However, since every oven has different firing characteristics, each decorator must establish his or her own cycle with the oven being used in production.
EquipmentA first-time user of the Cromalin Art system should expect to pay around $35 million for the following equipment:
The variable cost to produce one piece (13 x 18 cm) is typically around $9 to $10. However, since the net selling price of one piece is often between $60 and $80, equipment costs can be recouped quickly.