Kind of a silly question but I was reading more about the different types of bluing processes since I'm fairly ignorant regarding them. If I'm reading this correctly, it seems many of these (if not all) are acidic and corrosive which is how they get the color, but does this have any noticeable effect on an expensive, high carbon steel blade after a time (ie: cause increased pitting, weakening the steel, etc)?

Also is there substances out there to touch up scratched bluing or is it better to have someone (or yourself) polish it all down and do it again from scratch?

EDIT: Nevermind. Search functions help. I couldn't find an explicit answer but from the information I think I can imply one :)

Thanks Lin. One of the threads I was reading under the search function here mentioned that hot bluing can affect the temper of the blade if used on it. Is this true?

Do you know what kind of lye?

You have several options. Sodium hydroxide is what you want from the lye. Fairly clean grades of it are readily available as soap making supplies. It costs something like $2 U.S. per lb. I would recommend a seamless vessel (like a 300 series stainless stock pot and turkey fryer on low heat, improvised splash guard. Homebrewers usually have this. I have two 10 gallon vessels myself. The stainless should hold up to potassium nitrate and sodium hydroxide. More elaborate bluing recipes may ruin the passivation of the stainless though.) One should note that the batch starts off with water. Lye is added to water, NOT water added to lye (boom!)
The blade makers and gun forums usually have common fertilizer and household cleaning type substitutes.
http://castboolits.gunloads.com/archive/index.php/t-36054.html

http://www.geocities.com/kemays/formula.htm