Thank you all !! 
 
I'll try to find Nital 2%,  
don't seems easy to find. 
 
I work in an highschool; I will ask my colleague teaching physical if they have nitric acid in the laboratory and mix it with ethanol...( sure glasses, gloves and laboratory fume hood). 
We'll see ...
		 
		
		
		
		
		
		
		
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