Appliance Design - April 2008 - (Page 37)

Fig. 2. The LustReflex coating has been applied to the upper surface and conventional blue enamel has been applied to the reverse side of this one-meter by one-meter pane of glass. The LustReflex print shows the capability of this coating to form stripes, a checkerboard pattern and grayscale images in a semireflective appearance. DECORATION is a simple process comprised of four basic steps. Step 1 – Cleaning the Substrate. The substrate should be clean and dust free for the best results. Industrial washers can generally be used to prepare the substrate for printing. If an industrial washer is not available, then the substrate can be cleaned by hand with the following method. 1. Scrub the substrate with a carbonate-based cleaner such as Alcanox or Sparkleen. 2. Rinse the substrate with hot water. 3. Rinse the substrate with DI water. 4. Dry the substrate with an air knife. The compressed air supply should be oil free. If an air knife is not available, lint-free towels can be used to dry the substrate. If print defects are still present, insert an ethanol rinse between steps 3 and 4. Step 2 – Printing the LustReflex Coating on the Substrate. The LustReflex coatings are unique because a small change in the concentration of the active material in the coating or the film weight of the coating applied to the substrate can have a large impact on the appearance of the fired film. For this reason, changing the film weight and the concentration of the active material in the coating are two techniques that are used to tune the appearance of the final, fired LustReflex coating. Tuning of the appearance could well be necessary during the launch of a new application. With the Silver LustReflex coating (TLU0050A), the following progression of appearances can be obtained by increasing the film weight with various screen meshes. 1. The fired coating is silver in appearance, with a low reflectance. 2. The fired coating remains silver in appearance, but the reflectance is stronger. (See Fig. 1A.) 3. The fired coating begins to take on a burnished silver appearance. (See Fig. 1B.) 4. The fired coating begins to show yellow, red and green interference colors. 5. The fired coating shows a blue interference www.applianceDESIGN.com .com color. (See Fig. 1C.) 6. The fired coating becomes cloudy and white in appearance. This large variation in the appearance of the coating means that the glass substrate should be as flat as possible. In other words, glass that is warped by a prior heating cycle could cause undesirable variation in the appearance of the coating. If the wet coating does not level well due to atmospheric dust, a dirty substrate or for some other reason, the coating can take on different appearances where the film is thicker or thinner. To obtain the desired appearance, each customer will need to test the coating in their application and make adjustments based on these results. Step 3 – Drying the Substrate. The substrate is passed through a belt drier to dry the solvents out of the coating. In place of a belt drier, drying ovens or hotplates could be used. In an automated line, this step will simply precede the firing. Step 4 – Firing the Substrate. The substrate is passed through a normal decoration fire. The TLU-0050A coating has been fired on various vitreous substrates from 1,000 DegF to 1,900 DegF. Another advantage of the coating is that it can pass over the rollers in a tempering kiln following the firing process without damage. This allows the decorator to apply the LustReflex coating on one side of the glass and then turn it over to apply conventional glass enamel to the other side. Good contrast can be obtained when this method is followed. (See Fig. 2.) The LustReflex coating is very durable. The coating is resistant to several solutions at room temperature and panels display good weather durability. However, the LustReflex coatings do not fare well in hot alkali environments. See Table 1 for further details. As noted earlier, the LustReflex coatings produce a semimirror appearance when applied to vitreous substrates. In Graph 1, the Percent Reflectance data are presented for two pieces of soda-lime glass: one treated with the LustReflex coating and one untreated. The reflectance values of the LustReflex-treated glass are higher than those of the bare substrate at all wavelengths measured. Recently, there has been a demand for glass coatings with the appearance of metallic surfaces. The semi-mirror characteristics of the LustReflex coatings allow for the design of these new coatings, including an imitation brushed stainless steel. The application of an imitation brushed stainless steel coating is a process comprised of Test 10% NaOH 1 N H2SO4 3% HCl 10% Citric Acid Water Weathering Conditions 2 hr. immersion at RT 2 hr. immersion at RT 2 hr. immersion at RT 2 hr. immersion at RT 2 hr. immersion, boiling South exposure on building Result Fired coating is un-affected Fired coating is un-affected Fired coating is un-affected Fired coating is un-affected Fired coating is un-affected Fired coating is un-affected Table 1. Durability tests and their results for the LustReflex coating on glass. applianceDESIGN appliance April 2008 37 http://www.appliancedesign.com

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Appliance Design - April 2008 Contents Editorial Shipments/Forecasts News Watch A Variant of Thermoacoustic Refrigeration Known as Acoustic-Stirling is Expanding Its Range Outside Cryocooling Into More Conventional Applications Such As Refrigeration and Air Conditioning Free-Piston, Stirling Coolers Are Now Showing Up in Mainstream Applications As Costs Come Down and Heat Transport Solutions Are Devised Heat Exchanger Innovations Are Helping To Improve the Overall Efficiency of Vapor Compression Systems Environmental Concerns Have Once Again Ignited a Debate Over Refrigerants A New Glass Ceramic Material for Induction Cooktops Can Be Decorated In a Variety of Glimmering Metallic, 3-D Looks That Can Employ a Number of Shades, Patterns, Styles, Colors, Intensities, and Textures Colorful, Reflective Coatings for Glass Create a Variety of Design Options To Help Designers Establish a Unique Look for Their Products Appliance Designers Faced With Different Motor and Drive Options Need To Understand the Differences and Tradeoffs Before Choosing A New MEMS Valve Offers a Number of Advantages Over Solenoids In Certain Applications, Including the Opportunity To Cut Energy Use The AHR Expo Set Attendance Records and Showcased Thousands of Innovative New Products Classifieds Design Marts Advertiser’s Index Association Report: CEA

Appliance Design - April 2008

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