## 7 Cost Comparison  
The cost comparison of the two different processes is not easy. The purchasing, planting and setting up costs of an industrial production plant depend on multiple factors that make the cost analysis complex. In this approach, it was taken into account the fact that the company defined its turnover and productivity annual-target, and therefore purchased the two conversion-coating systems, the rinse and the no-rinse one, of comparable productivity. Considering that the no-rinse system has a roll-coater or a sprayer, which, therefore, is more complex than the rinse one, but that the latter requires at least two more tanks and ancillary equipment, it was assumed that the two plants had similar costs, and so this was not considered as a variable to discriminate between the two processes. In addition, the costs of piece handling, stops for the renewal of the tanks, maintenance, etc., were estimated to be similar, and not considered. It should be noted that the no-rinse raw material is offered at a price per unit of mass approximately double the price of the rinse one (Table 5).  
Figure 8: (**a**) Impedance modulus \(|\,Z\,|\); (**b**) phase angle plots of CNR sample immersed in an aerated 3.5 wt.% NaCl solution for 7 days.  
Furthermore, the no-rinse product is used by depositing a wet film of thickness equal to approximately 2-2.5 times that used for the rinse product (0.7-0.8 g/m\({}^{2}\) vs. 1.4-2.0 g/m\({}^{2}\)). At the same time, however, the no-rinse product is diluted up to 30-40% to obtain an adequate product-distribution on the foil surface. In the end, the raw materials' costs differ slightly if quantified in terms of cost per square-meter of treated foil.  
In light of the recent findings relating to climate changes caused by the anthropic and industrial impact on the world around us, the prerogatives of no-rinse products reside, mainly, in the reduced environmental impact and the decrease in the exploitation of water resources. The water quantity in the no-rinse process is equal to the amount necessary to dilute the product to the concentrations indicated (a part of the water used in the cleaning and the etching steps that is the same amount in both processes). The last step of the no-rinse conversion-coating process does not require the washing of the metallic film; therefore, there is no need to process the mains water to produce demineralised water, purify it at the end of the conversion process, and dispose of it in the ways permitted by current laws. Taking into account (Table 6) the company's annual average-production (40 \(\times\) 10\({}^{6}\) m with the standard width of 1.80 m), it has been evaluated that by using the no-rinse conversion-coating process, the cost of the entire production is approximately EUR 65,000, while using the CrIII rinse is EUR 45,000, representing a cost increase of approximately 31%. At the same time, the consumption of water was reduced by 13,000 tons/year, and the sludge to be disposed of was decreased by approximately 130 tons/year. Considering that the company produces the demineralised water estimating its cost to be 1 EUR/ton and the cost of the sludge disposal can be evaluated at approximately 235 EUR/ton, the overall saving can be estimated at approximately EUR 43,000 per year. Ultimately, the company, using the no-rinse product, achieves a net saving on production costs of around EUR 23,000.