Finishing 1 Objectives

What conditions work best for electroplating zinc onto a metal object Does changing the current affect the quality of the finished object ... 

Compare the three finished objects that you electroplated. What conditions worked best to electroplate zinc onto a metal object ... 

China clays, also referred to as kaolins, are used to produce traditional ceramics when the color of the finished object and its high temperature performance are important. 

Methods of obtaining the metal or alloy from its ores will be briefly covered here as with the possible shaping processes to produce the finished object. The corrosion behaviour of the metal while buried will also be discussed and this will be related to various methods available in the conservation of these materials. 

Table IV. Summary of Some Wet Chemical Finishing Objectives and the Textile Chemicals Employed to Obtain Thera...

Although the dynamic mechanical properties and the stress-strain behavior iV of block copolymers have been studied extensively, very little creep data are available on these materials (1-17). A number of block copolymers are now commercially available as thermoplastic elastomers to replace crosslinked rubber formulations and other plastics (16). For applications in which the finished object must bear loads for extended periods of time, it is important to know how these new materials compare with conventional crosslinked rubbers and more rigid plastics in dimensional stability or creep behavior. The creep of five commercial block polymers was measured as a function of temperature and molding conditions. Four of the polymers had crystalline hard blocks, and one had a glassy polystyrene hard block. The soft blocks were various kinds of elastomeric materials. The creep of the block polymers was also compared with that of a normal, crosslinked natural rubber and crystalline poly(tetra-methylene terephthalate) (PTMT). 

Simple shapes such as traditional vases may be made in one piece, a skilled but fairly simple operation. For complicated shapes like figures, or even just the handles for our vase, the original model will have had to be cut up and the finished object made in a number of parts. It is at this stage, when the clay is basically dry but still in what we call a green or leather state, that the parts are reassembled. In the case of a simple vase it may just be a simple case of dabbing a little of the original slip onto the ends of the handles and sticking them carefully in place. 

The fact that the mould was in two parts inevitably means that the slip will seep a little into the join. This leaves a small ridge around the finished object much like the seam linking the two halves of a chocolate Easter egg this seam needs to be scraped down and cleaned up, a delicate and skilled job. 

Pressing needs a mold that will be gray cast iron (to 1000°C), stainless steel (can be used for borosilicates at 1185°C and glass ceramics at 1480°C), or even bronze. Usually, though, the mold is cooled. The process uses a viscosity of 4kP and has been applied to objects weighing from 5g to 15 kg. The finished object can be fire-polished. This process, shown in Figure 23.19, is quite... 

The purpose of an operation sheet is to set out the most economic sequence of operations required to produce a finished object or process from the raw material. Although the main purpose of operation sheets is to set out the sequence of operations, they also serve a number of other very important functions ... 

To convey the message or information clearly it is better to make your sketch large rather than too small. It should also contain all the dimensions necessary to indicate clearly the size of the finished object depicted by the sketch. 

Lacquering or varnishing consists of covering the finished objects with a layer of plastic material. Two decades ago, nitrocellulose was used. Nowadays, modern electrolytic systems are used to deposit plastic material that becomes transparent at high temperatures. The resins used are polyurethane, vylinics, acrylics and epoxy. We also should take into account chrome, nickel, cobalt and various metallic oxides which can be found in enamels (Motolese et al. 1993). 

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