Properties of Zinc

 

Zinc is a grayish - silver metal that is the standard sacrificial coating when protecting ferrous metals from red rust. Zinc is suitable for both outside and inside coatings since zinc coated steel (due to galvanic protection) will not rust even when exposed by scratches. On weathering, zinc turns to a drab gray color.​ Post treatment is necessary to significantly protect zinc from oxidizing as white rust. ​

At TP zinc plating can be specified as alkaline or chloride. Alkaline zinc is preferred if there are recesses and orifices that are difficult to get into. It also deposits in columns which helps subsequent passivation to soak into the part. Alkaline can be brightened but, it lacks the superior brightness of chloride zinc. All rack zinc at TP is Alkaline zinc and all rack pieces are inspected 100%.

The alternative, chloride zinc is our go-to for barrel plating. Barrel plating is the most economical way to plate durable parts. Not all parts can be barrel plated...depending on the geometry. Flat parts or those with deep orifices tend to be best plated on Alkaline. Otherwise, chloride zinc has superior brightness and can be plated to over 1 mil of thickness with additives.

Chromate Color Selection
Zinc plating protects steel from red rust. Chromates protect the zinc coating from white rust. These are the two specifications that are called out for salt spray. All of our trivalent chromates are hexavalent free and comply with current REACH, ELV and ROHS Regulations. TP offers 3 chromate colors to suit your customers requirements. 
Clear Zinc 
Sometimes referred to as white or blue zinc due to it's bluish white iridescence, is the most commonly specified zinc. Our clear chromate is able to achieve better than 175 neutral salt spray hours to white corrosion. this is partially due to the cobalt contained in the formulation. To put this into perspective. The highest ASTM standard specified is 120 hours without supplementary topcoats. Our clear zinc is available is both rack and barrel. 
Yellow Zinc 
Sometimes referred to as gold zinc due to it's brilliant golden color. Our yellow chromate selection is formulated similarly to our clear product and is able to achieve better than 175 neutral salt spray hours to white corrosion as well. This product can have a wide range of coloration based off of your specification. Some customer prefer a soft yellow and others desire a strong gold. We have the experience to match your requirements. Our yellow zinc is available in both rack and barrel.
Black Zinc 
Technical Plating has a lot of experience with black zinc. Our black zinc is able to exceed 168 hours of neutral salt spray to white corrosion without supplementary topcoats. Black zinc is typically specified due to it's appearance. Black zinc has real advantages over other dark finishes such as black oxide which provides minimum corrosion resistance while still imparting a dark beautiful sheen. Other than salt spray, the primary difference is the thickness of black zinc as Zinc oxide is much thinner than black zinc that can be specified in ranges from .00005" to over 1 mil of thickness. Our black zinc can be specified in both rack and barrel. However, barrel can exhibit some edge chipping on the continuous black finish.
Trivalent Zinc Plating
Clear Zinc Plating
Yellow Zinc Plating
Black Zinc.jpg
Our Capabilities

Te​chnical Plating offers high volume alkaline and chloride zinc over most steel substrates with trivalent clear, trivalent yellow or t​​​rivalent black chromate passivations. We have barrel and rack capabilities for zinc. Rack parts are inspected at 100%.

 

Standards

  • ASTM B633

    • ​Service Condition 1,​ Mild, ​Fe/Zn 5, .0002"

    • Service Condtion 2​, Moderate, Fe/Zn 8, .0003"

    • Service Condition 3, ​Severe, Fe/Zn 12, .0005"​

    • Service Condition 4, Very Severe, Fe/Zn 25​, .001"

    • Type I: As plated without supplementary treatments ​

    • Type II: With colored chromate coating (96 hr salt spray min)

    • Type III​:​ With colorless conversion​ chromate coating​ (12 hr salt spray min)​

    • Type IV: ​With phosphate conversion coating

    • Type V: With colorless passivate (72 hr salt spray min)

    • Type VI: With colored passivate (120 hr salt spray min)

  • QQ​-Z-325B

    • Class I: .001" Severe Service

    • Class II: .0005" Moderate Service

    • Class III: .0002" Mild Service

    • ​Type I​ Without supplementary treatments

    • Type II With supplementary chromate treatment

    • Type III With supplementary phosphate treatment

  • In-house developed standards ​

 

Chromates

  • ​Trivalent Clear

  • Trivalent Yellow

  • Trivalent Black (limited for barrel plating)

 

Testing Methods

  • ​X-Ray Flourescence

  • Eddy Current