rust remover solution 2

 Continuation or update from thread: 

https://www.blogger.com/blog/post/edit/3024196247730049917/5613445502601298195

Potassium oxalate suggested in the video: chemical store price where I live turn out very expensive (PHP1,800 for 250grams); no go for me.

I found out that the oxalic acid used in laundry to whiten white shirts produce same result. And this chemical is very cheap. It'd remove rust easily. Serve also as decent degreaser. Found out also many people in youtube are using it.

This is a 428 size 42T rear sprocket with matching chain without all those rusts any longer upon closer inspection (immersed for 2-3 hours in oxalic acid):

The chain would even pass like it had been given black oxide finish. 

I apologize because I don't have before/after pictures.