I was taking a stroll through the internet, a week or so ago, searching for information on the paper used by the National Bank of Ukraine - Banknote Printing and Minting Works for banknote production, and stumbled upon a really wonderful document titled Banknote Paper Deterioration Factors: Circulation Simulator Method, authored by Tetiana Kyrychok, Anatolii Shevchuk, Victor Nesterenk, and Petro Kyrychok. Normally I like to skim over items such as this, gleaning what I think is pertinent to my field of interest, but after "skimming" I saw that a Ukrainian banknote was used for testing in the simulator, I was hooked (a 2 Hryvnia, pre 2014 issued note was used, as the banknote paper composition has been changed by the NBU since publishing). The paper is 15 pages of technical jargon and I loved every word of it.  

While the paper strictly focuses on banknote "Deterioration" I think that it also translates well to other areas of banknote collecting, for example. Knowing how/why the breaking down (deterioration) of notes happens and the root causes help with grading (I think), in that you are better able to identify problem areas such as types of waviness, changes in color in certain areas of the note and in certain color spectrums, yellowing, brightness, effects of thermal effects, UV degradation, weight loss and on and on and on.. It also helped shed more light on (again for me) proper storage, mainly what not to do, and how climate/storage area will effect notes. 

While the simulation results are probably not going to be relatable to most notes as banknote paper composition is frequently changing, polymer is becoming evermore popular, and the results are no longer valid for post 2016 Ukrainian notes as the paper makeup was changed at that time but the reasons for deterioration all remain valid. Below are a couple of charts from the paper showing general methods of deterioration and factors from circulation.

If you have a free moment or a quite evening this paper is definitely worth checking out. 

Banknote paper deterioration factors: Circulation simulator method :: BioResources (ncsu.edu) 

Ukraine 2013 issue 2 Hryven banknote. This series was printed from 2004 - 2013, presumably this series note was used during testing.