Black Oxide Temp Guide

Birchwood Technologies Black Oxide Temperature Guide

Birchwood Technologies Black Oxide Temp Guide

Birchwood Technologies offers a wide variety of black oxide processes, otherwise known as metal blackeners. Black oxide works at three basic temperature ranges from 65° up to 285° F. The black oxide coating is created by a chemical reaction that takes place on the surface of the metal. The resulting black oxide surface creates major advantages over paint coatings and in many cases has become the preferred coating method for iron and steel components for these advantages:
  • Cosmetic appeal
  • Non-dimensional coating, no interference with part function
  • Break-in lubricity and anti-galling properties
  • Rich black finish
room-temperature blackening

Room-temperature blackening (65° to 85° F), also referred to as cold blackening, is a preferred low cost in-house blackening process due to safe operation. It offers an excellent way to achieve good corrosion protection and enhance sales appeal. The porous crystalline structure of the black finish has a uniform 0.000030 inch (1 micron) thickness.

Room-temperature features:

  • Excellent absorbent base for a rust preventive topcoat
  • 5-8 minutes parts cleaning
  • Water rinse
  • (Optional) 1-3 minutes surface conditioner provides a more reactive/receptive metal surface
  • Water rinse
  • 1-3 minutes to blacken parts
  • Water rinse
  • 1-3 minutes sealant
  • Black satin finish
  • Lower heating costs
  • Blackens cast iron, steel, and most powdered/sintered metals
  • Appropriate versions can be used to blacken most stainless steels.

Products: Presto Black

mid-temperature black oxide

Mid-temperature black oxide (200° to 210° F) operates at substantially lower temperature than traditional hot black oxide (temp 285-290° F) with a comparable finish. It has become an ideal replacement for hot oxide due to safer operation and lower heating costs. Forms a black magnetite (Fe3O4) finish on all iron and steel parts, not including stainless steel.

Mid-temperature features:

  • Blackening process takes approximately 25-30 minutes
  • Attractive satin black to semi-glossy black appearance
  • Resists galling and aids in break-in
  • Mil Spec and RoHS compliant
  • Withstands up to 120 hours of neutral salt spray or several hundred hours of humidity
  • Operating solutions contain no EPA regulated chemicals; process rinse waters are normally sent to the sewer as non-hazardous discharge
  • Most counties do not require waste treatment equipment
  • Saves on heating and energy costs

Products: Tru Temp

hot-temperature black oxide

Hot-temperature black oxide (285° to 290° F) operates at the highest temperature of all conventional black oxides. This is a conversion coating formed by a chemical reaction produced by the alkaline salt solution and the immersion of the metal parts. This process is usually performed only by highly trained metal finishing companies. Closely monitored chemical balance is required to prevent salt bloom and discolored red-black coatings. Water balance and proper controls are required to prevent steam explosion.

  • Blackens in 30-60 minutes
  • Glossy blue-black finish
  • Produce no dimensional change
  • Large batches (ideal for small parts)
  • MIL-DTL-13924F compliant
  • AMS 2485, ASTM D769, and ISO 11408 compliant

Products: Birchwood Technologies does not manufacture a hot oxide at this time. We developed our mid-temperature black oxide as a safer replacement to the extreme operating temperatures for hot oxide.