Presto Black Black Oxide, Microlok MZN Zinc Phosphate

January 01, 2015

PRESTO BLACK room temperature black oxide and MICROLOK MZN zinc phosphate processes from Birchwood Technologies are becoming increasingly popular for use on oilfield equipment requiring robust corrosion resistance and galling protection on critical surfaces. Both processes easily coat iron and steel components and are applied at safe temperatures.

The PRESTO BLACK process produces a non-dimensional coating thickness of less than 0.5µm thickness and is ideally suited for components that require a black finish for visual appeal. PRESTO BLACK is a short fifteen-minute process that eliminates the hazards of the hot oxide process by operating at room temperature. It provides high corrosion resistance and is tested for up to 1200 hours humidity exposure when sealed with an appropriate rust preventive.

The MICROLOK MZN zinc phosphate produces a heavier coating of about 5-10µm thickness, and is gray/black in color. This process is ideally suited for applications that require robust protection from galling and corrosion but do not require a black color. MICROLOK MZN is a short twenty-minute process that operates at a safe temperature of 140-160° F with no boiling or splattering. It provides protection up to 1400°F for high heat applications such as brake components.

The PRESTO BLACK and MICROLOK MZN processes offer a friable crystal structure that serves as a sacrificial barrier on sliding surfaces to protect the underlying steel itself from galling and deformation. Both coatings are widely used and approved by the oil industry and recommended for finishing hot rolled steels, alloy steels, tool steels, as well as cast iron, forged steels and powdered metal. These finishing processes are reportedly ideal for both large and small parts held in storage and shipping, then put into service corrosion free.

Full tank lines are available in a variety of sizes, and come with full tech support from Birchwood Technologies. Birchwood Technologies also offers fully automated finishing lines to further increase the value of these finishing systems. To enable OEMs to offer both coatings to customers these processes can be installed individually, or in a combination process line that utilizes several common steps.

PRESTO BLACK and MICROLOK MZN can operate with zero discharge of rinse waters using the Birchwood Technologies Ion Exchange System. It cleans and purifies the process rinse waters so they can be re-used rather than sent to the drain. Once available to large companies only, this technology is low cost and routinely utilized on process lines of all sizes with excellent success.

Related Glossary Terms

  • alloy steels

    alloy steels

    Steel containing specified quantities of alloying elements (other than carbon and the commonly accepted amounts of manganese, sulfur and phosphorus) added to cause changes in the metal’s mechanical and/or physical properties. Principal alloying elements are nickel, chromium, molybdenum and silicon. Some grades of alloy steels contain one or more of these elements: vanadium, boron, lead and copper.

  • black oxide

    black oxide

    Black finish on a metal produced by immersing it in hot oxidizing salts or salt solutions.

  • corrosion resistance

    corrosion resistance

    Ability of an alloy or material to withstand rust and corrosion. These are properties fostered by nickel and chromium in alloys such as stainless steel.

  • galling


    Condition whereby excessive friction between high spots results in localized welding with subsequent spalling and further roughening of the rubbing surface(s) of one or both of two mating parts.

  • tool steels

    tool steels

    Group of alloy steels which, after proper heat treatment, provide the combination of properties required for cutting tool and die applications. The American Iron and Steel Institute divides tool steels into six major categories: water hardening, shock resisting, cold work, hot work, special purpose and high speed.