1. DIANA DE LA FELD 迪安娜 1156371

2. * The chalkboard is a flat, vertical writing surface on which anything can be inscribed by means of chalk piece: it is widely used all over the word mostly for educational purposes. * The modern chalkboard was first patented in 1823 by Samuel Reed Hall, a leading educator of the day. * The earlier products were simple pine board painted black and than developed in a combination of lime, plaster of Paris and lampblack.

3. * GALVANIZED STEEL: the front and the back surfaces of the chalkboard are formed of thin sheets of galvanized steel, that enter the manufacturing facility from an outside supplier in pre-cut standard sizes * PAINT: it is a type of acrylic enamel designed specially for chalkboards to which a powdered mineral formulation is added to make the coating dry to a rougher texture * SLIP: it is applied to the steel surface, it is made of SILICA, a crystalline compound derived from quartz or similar minerals (silicon and oxygen)  the surface of the chalkboards is usually a blend of inorganic compounds as a powder glass opacifier and oxides * CONTACT CEMENT: it is used as an adhesive for assembly * ALLUMINUM MOLDING: used for the board frame

4. ① COLD-ROLLING: the sheet sheets undergo a cold-rolling process in order to increases the strength (strain hardening) and the surface finish ② CHEMICAL WASHER: it blasts the sheets with acid to remove dirt that would prevent paint to inhale to the surface ③ DRYING: at the exit from the cleaner the sheets are cooled off by powerful fans

5. ① SLIP APPLICATION * The steel sheets pass through a COATING CHAMBER where SPRAY GUNS apply a layer of slip of at least 0.026mm  the slip is left to dry * FIRING: the sheets enter a large furnace area where they are subject to a temperature of 218°C for 10’  this process softens the steel and allows fusion of the slip with the steel The steel sheets are subject to a coating process that comprehends two major steps: SLIP APPLICATION & SURFACE COMPUNDS

6. * the surface is treated with a SURFACE-COATING COMPUND, usually derived from glass opacifiers and gives a smoother texture to the board (oxides for color can be added during this step) * also this layer must be at least 0.062mm * the sheets are completely cooled and dried * COVER COAT FURNACE, the sheets go through a heating process (at least 649°C) to fuse the first ground coat with the surface coat * COOLING CHAMBER the temperature is gradually reduced so that the flat sheets do not buckle or weaken ② SURFACE COMPUND

7. * ASSEMBLY contact cement is sprayed on the back of two painted sheets which are assembled with the CHALKBOARD CORE placed in between, usually a 12mm fiberboard * HIGH PRESSURE ROLLER the tree layer assembly is fed into the roller in order to force out any trapped air and bonds the layers tightly

8. * the board frame is made out of one long strip of aluminum molding, that has a stain proof satin finish * a series of 45° angle cuts are made  this enables the workers to bend the frame around the board perimeter, creating neat corner scenes * The frame is finally fastened to the board, during this step other extra components, depending on the boars model, can be added * QUALITY CONTROLL is made before the board can finally be introduced in the market