Evaluation of the Protective Varnish on Brazilian Real Banknotes

The present article assesses the effectiveness of the protective varnish that coats the R$2 and R$5 bills of the second Brazilian real series based on representative sample of banknotes in circulation throughout the country. Two comparative evaluations were carried out involving: (i) banknotes with and without varnish (R$5 x R$10); and (ii) banknotes with two different types of varnish (used in different productions of the R$2 banknote). Unlike previous studies carried out by other issuers, this work evaluated a representative sample of the banknotes in circulation throughout the country and not in a controlled experiment with limited samples and regions. For the calculation of the useful life, the sample banknotes were classified according to wear levels and those classified as level 4 to 6 should be withdrawn from circulation. The time in circulation was calculated based on the dates of issue and withdrawal from circulation. Survival analysis allowed the comparison between banknotes with and without application of varnish, considering both banknotes that had already reached this level of wear, as well as those that were in better situations. The study showed the adoption of varnish increased protection against dirt and wear. However, it was found the effectiveness of the varnish is limited: the protection reduces over time, and in about two years there is no longer any difference between banknotes with and without varnish.