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			 Member 
			
			
			
				
			
			Join Date: Sep 2014 
				Location: Austria 
				
				
					Posts: 1,912
				 
				
				
				
				
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			Regarding cleaning the knife, I fully agree with Detlef.  
		
		
		
		
		
		
		
	What you think is patina, is actually rust. While black rust is less active (but still active) and may contribute to the character of a blade, brown rust does nothing but damage the blade. And it is precisely brown rust what you have on your blade. Moreover, it is as you said a 19 century blade (best case scenario) but it can also be from early 20 cent, so not so old. While is I consider acceptable to have some black rust on a 16-18 century blade, I find it less acceptable on such a recent blade. But this is my personal oppinion. It is your blade abd your call.  
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