Metal finishing Q&As since 1989



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Metal blueing problem

This is a solution problem. I have blued a number of parts in the past. I have mixed up a new batch of blue salts this morning. I am having difficulties with though. my start of boil is at 275° (full boil 285°) I used a new supplier of salts and used distilled water for the first time. I have always used tap or regular bottle water previously. This time I can not get the first part to blue. I have tried several different pieces. I am not sure if salts are correct. It says and I was also told it was technical grade 98% pure. I am just assuming they are because of boil temp. I bought in bulk this time and hope I didn't get taken.
I have tried to shock and use more heat. 325 or so. Still no avail. any help would be appreciated. Thanks, Skip

Skip Kalmar
gunsmith - Heath, Ohio, USA
December 17, 2010

More details please - tell us something more about your solution-which salts you use,on which kind of steel etc.etc.Sodium hydroxide and Sodium Nitrate [affil links]?

Goran Budija
- Zagreb,Croatia
December 25, 2010

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December 30, 2010

Well you kind of just gave us the carburetor off of your car and asked us why it won't start. I take it parts go in silver and come out silver?

(1) Bad salt to water ratio, salts not at a rolling boil at full temp or you are not cycling the temperature of the bath with water as a temperature controller.

(2) Broken thermometer always run the batch's with 2 thermometers.

(3) Trying to blue stainless steel probably 416, 303 or 304. Test part with cold blue to check.

(4) Trying to blue nickel steel move temperatures up to 310F by letting water boil away and shock parts.

(5) Salts have been over heated and burned. Check by test blueing a piece of 4140 ordnance grade steel or 1018. Replace with new salts.

(6) Contaminant floating on the surface of salts. Over-spray from oils or stock finishes. Skim the surface of the salts when hot with paper towels.

(7) Bad hair day?

Rod Henrickson
gunsmith - Edmonton, Alberta, Canada

Sorry I haven't gotten back sooner. I was out of town. I have since gone back to original salts. Everything is good once again. I have blued several guns including the one I had trouble with. I believe the cheaper salts were not up to grade. Thanks Skip

Skip Kalmar
- Heath, Ohio
January 10, 2011