Conventional dipping

Electrodeposition This method of paint application is basically a dipping process. The paint is water-based and is either an emulsion or a stabilised dispersion. The solids of the paint are usually very low and the viscosity lower than that used in conventional dipping. The workpiece is made one electrode, usually the cathode, in a d.c. circuit and the anode can be either the tank itself or suitably sized electrodes sited to give optimum coating conditions. The current is applied for a few minutes and after withdrawal and draining the article is rinsed with de-ionised water to remove the thin layer of dipped paint. The deposited film is firmly adherent and contains a minimum of water and can be stoved without any flash-off period. This process is used for metal fabrications, notably car bodies. Complete coverage of inaccessible areas can be achieved and the corrosion resistance of the coating is excellent (Fig. 14.1). 

The conventional type of bake oven is used. Electrodeposited coats are usually baked from 5 to 30 min at temperatures varying from 225 to 400 F. The air velocity through the oven can be comparatively low, due to the very small quantities of organic volatiles in the paint coat. The time/teraperature requirements are dictated by the resin system and are similar to those required for conventional dip or spray paints—usually 5-25 min at 225-400 °F air... 

Conventional Dipping. In conventional dipping the workpieces are immersed in the paint and then removed (Fig. 8.2). The liquid paint adheres to the surface and is then dried or stoved. Care should be taken to ensure that the workpieces do not float during dipping and that air bubbles do not become trapped. The speed at which the workpiece is removed from the bath must be selected so that excess paint adhering to the surface can run off The draining and evaporation time must be sufficiently long to ensure satisfactory evaporation of the solvents (if necessary a hot air zone should be included for waterborne paints). 

Figure 8.2. A conventional dipping unit a) Edge suction b) Overflow c) Circulation system with pump, filter, piping, and nozzles d) Dipping lank e) Heating and cooling device f) Cover (in the form of roller-type covers) g) Raising and lowering system h) Workpiece...

However, the best results were presented in a series of papers where the methylester tetramer was used as an element in an ISE array both in conventional dip-type measurements [14] and in a flow-injection analysis system [15,16]. Using sophisticated calibration and sensor modelling techniques, these papers rigorously demonstrated that the methylester tetramer (Table 1,2) could be applied to blood sodium analysis with excellent results (Figure 3). Furthermore, the same ISE was shown to be suitable for the analysis of sodium in mineral water samples. 

Use of protease in dehairing of Black Angus steer hide derived from a strain of Streptomyces griseus (Gehring et al., 2002) is reported. A multiple proteinase concentrate from the culture filtrate of Streptomyces moderatus has been developed and a novel spraying technique has been standardized in place of conventional dip method or painting method (Chandrasekaran and Dhar, 1985). 

In another approach, commercial TLC plates of silica gel 60 F254 were first carefully washed, by predevelopment, with methanol/water (9 1, v/v), then dried at ambient temperature for 3 h, and these were then impregnated with a 3 x 10 mol/1 solution of L-arginine in methanol by conventional dipping for 2 s [10,11]. The concentration of the impregnating solution was calculated as that depositing 0.5 g L-arginine per 50 g of the dry silica gel adsorbent layer. 

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