Sounds like you are using too high a heat and too quickly and burning the substances before melting into a usable substance.  You sould not have any problems.   
Use a gentle flame from a small spirit/meths burner or even a big spoon over a candle except a yellow flame will soot up.  If you cannot find one work with embers of a fire like any native / jungleman.
		 
		
		
		
		
		
		
		
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