Black oxide is a blend of caustic, oxidizers, and additives that is used on ferrous metals. There are three types of metal blackening: hot, mid, and room temperature blackening. EPi was the first company to offer all three processes.
Hot black oxide (285 F°) is a conventional hot process which produces a true black oxide iron magnetite (Fe3O4) finish. It is a premium-grade salt mixture which will blacken a wider range of steel alloys than any other process on the market.
Mid-temperature black oxide (225–245 F°) is the latest development in blackening processes, producing a true black oxide iron magnetite (Fe3O4) finish. It produces no caustic boiling fumes and provides a safer working environment.
Room-temperature blackening (65–85° F) is the preferred metal-blackening process for safe and convenient in-house blackening. It is an excellent non-bleed black finish for powdered metal and cast iron. It produces super deep blackness and corrosion resistance equal to hot oxide blackeners.
It is important to note this is not a true black oxide process; however, it may be referred to as room-temperature black oxide. Room-temperature blackening processes are autocatalytic reactions of a black selenium-copper compound that deposits on ferrous parts through an immersion process.
What makes EPI’s black oxide and metal-blackening processes better?
Insta-Blak processes do not produce smutty rub-offs like other room-temperature products. Our Ultra-Blak products are premium-grade black oxide, and Kool-Blak does not produce a smutty rub off like other mid-temperature processes. They are easy-to-use with wide windows of operation.
What are the advantages of black oxide and metal blackening?
Produces true black oxide finish Fe3O4 magnetite finish
Meets military spec MIL-DTL-13924D and AMS 2485H
Blackens faster than other hot black oxides
Less sludge generation than other hot black oxides, which means lower gas bills
Capital costs less than $10,000–15,000 for turnkey operations
No CO2 emissions or green house gases
1–5 minute process time for blackening
Powder metal does not bleed-out white salts like hot black oxide
Cast iron and steel castings do not turn red
No ventilation costs
Provides corrosion resistance
Dimensional stability thickness 5–10 millionths of an inch
Can be painted over
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