I just read what a passivated finish on stainless steel barrels was (due to seeing that sionics does this) and was wondering if this was common to most/all stainless barrels on the market?
It has to be pretty standard. Un-passivated SS rust pretty quickly. I was wanting to by a pump bottle of passivation spray to treat my LE Wilson loading dies, because they rust from my hand sweat/oils.
I figured it must be after finding out what it was thanks
Passivation is over rated. Higher hardness grades such as 400 series stainless are more prone to corrosion no matter what you do. Whenever you see a stainless that is highly corrosion resistant it is generally the softer 300 series. Passivation is not a bad thing, but just don’t expect 18-8 (304) levels of corrosion resistance out of one of the common high hardness grades (such as those used for your dies).
Makes sense. Yeah… those dies rust pretty easily.
Passivation is the process of stainless creating it’s protective chromium oxide layer. It occurs naturally and does not need to be induced but takes up to 72 hours. The reason for inducing Passivation is to expedite the process to ensure that nothing will start corroding the stainless before it’s had a chance to form it’s oxide. Definitely can be useful in manufacturing if the customer wants to spend the extra money but not always necessary. 300 series ss has nickel added to it to increase the corrosion resistance exponentially but it causes it to be unheat treatable and more prone to galling hence why it’s not used to make dies. 400 series stainless is more of a chrome steel and is able to be hardened. It’s much less corrosion resistant without the nickel. It will form minor surface rust but should be able to be cleaned off without damaging the ss. It should be viewed more as a minimal maintenance steel unlike 300 series stainless. The process of Passivation is done using acids and electricity to jump start the oxidation process.
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If you want you can passivate your own stuff with citric acid…
http://www.theruststore.com/CitriSurf-77-22-oz-Bottle-P136.aspx
Although, by the time you get your barrel delivered, it will either be slightly rusty or will have the oxide layer formed.
Excellent posts, gentleman.
“Over-rated” That a bit strong. In initial manufacture, it is important to passivate after machining. It does remove free iron from the surface and improve corrosion resistance.
Passivation is not like oiling a blue barrel, after the chrome oxide layer is formed, that’s all the protection you’re going to get. Spritzing stainless steel with citric acid won’t make the oxide layer thicker or stronger.
Maybe misinterpreted is a better way to refer to it, I just get the feeling that some people assume it will provide more protection than it does.