julien_damours Posted August 19, 2009 Share Posted August 19, 2009 Hi, I have forged some kitchen knives out of coil spring. I think they were made of 1090 or 5160. I have polished my blades up to 2000 grit. But the problem is that when I use them for cutting food, some stain (blackish stain) appear on the blade and can only be removed by sanding it with the 2000 grit. Washin do not remove those stain. The worst seems to be when I cut some onion. It make an effect similar to etching the blade. So, I would like to know if there is a way to protect the blade from this. tkx a lot Quote Link to comment Share on other sites More sharing options...
matt87 Posted August 19, 2009 Share Posted August 19, 2009 It looks like it's etching the blade because it is; certain foods contain various acids. You can wash the knife immediately after use to reduce the staining but this 'patina' is just part and parcel of using a plain steel knife in the kitchen. Quote Link to comment Share on other sites More sharing options...
Dragons lair Posted August 20, 2009 Share Posted August 20, 2009 A little black is not bad. Bought some of those high carbon kitchen knives. Wife put them in the dishwasher come out bright orange. Ken Quote Link to comment Share on other sites More sharing options...
Rob Browne Posted August 20, 2009 Share Posted August 20, 2009 The very few knives I have made were all for the kitchen or workshop and out of old springs. All of the kitchen knives have ended up with stains and we are well and truely over trying to get rid of them (the stains that is). Just make sure they are clean and oiled (some cooking oil on a cloth) between uses and they are just fine. Must have been really common before stainless became the standard. Quote Link to comment Share on other sites More sharing options...
wolfshieldrx Posted August 20, 2009 Share Posted August 20, 2009 That ain't stain...that's patina. I wouldn't have it any other way. bart Quote Link to comment Share on other sites More sharing options...
devins Posted August 20, 2009 Share Posted August 20, 2009 Ah the carefree days of youth....We who are old enough still have to think back to the days when that was the norm. Come to think of it we used to have to spend a lot of time on preventive maintanence didn't we. We could sit around visiting while we polished and oiled everything(preventive or a whole lot more if restoring LOL) So is Stainless the problem with society today? Just Kidding, but you gotta love a good patina. Quote Link to comment Share on other sites More sharing options...
David Einhorn Posted August 20, 2009 Share Posted August 20, 2009 My recommendation is to "season" the blade just like any other traditional blacksmith made kitchen utensil. That way you have a deliberate durable black patina finish that is food safe. Quote Link to comment Share on other sites More sharing options...
julien_damours Posted August 20, 2009 Author Share Posted August 20, 2009 what do you mean by ''season'' the blade ? Quote Link to comment Share on other sites More sharing options...
David Einhorn Posted August 20, 2009 Share Posted August 20, 2009 Cast iron and other Iron cooking utensils are "seasoned" by applying cooking oil and heating:Cast Iron Cookware Seasoning CareSeasoning and Caring for cast iron cookwareLearn about Cast-Iron Pans, How to season and use cast-iron pans and skillets, Cast Iron Skillets, Cast Iron Cooking, Cast Iron Cooking RecipesCast-iron cookware - Wikipedia, the free encyclopedia Quote Link to comment Share on other sites More sharing options...
julien_damours Posted August 20, 2009 Author Share Posted August 20, 2009 hooo, I will read on this and try it tkx for the info !! Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted August 21, 2009 Share Posted August 21, 2009 WARNING; if you heat above your tempering temp you will soften the blade! Quote Link to comment Share on other sites More sharing options...
julien_damours Posted August 21, 2009 Author Share Posted August 21, 2009 hehe yea I will be careful ! In fact, it will soften the blade only if it is High carbon steel that has been heat treated to form martensite. Heating will make carbon diffuse out of the martensite microstructure and thus, decreasing the amount of martensite and form some pearlite wich is more ductile than martensite. Quote Link to comment Share on other sites More sharing options...
Christopher P. Posted September 9, 2009 Share Posted September 9, 2009 The trick with carbon kitchen knives, is to hand wash and oil immediately... and enjoy the "stain". Stainless was developed for people who like perpetual shiny, but it isn't the same as plain carbon steel. Quote Link to comment Share on other sites More sharing options...
julian Posted September 9, 2009 Share Posted September 9, 2009 It's already been said, but yep, enjoy that patina and welcome to carbon steel kitchen utensils :) Quote Link to comment Share on other sites More sharing options...
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