Galvanized steel is widely used for structural components, fabricated products, roofing, electrical equipment, outdoor installations and corrosion-protection applications. But galvanized steel creates an important question for coating inspection: What exactly are you trying to measure the zinc layer, paint over the galvanized steel, or the total coating system? This distinction matters when choosing a coating thickness gauge. The TASI TA521A and TA522A Coating Thickness Gauges include Fe+Zn measurement capability in addition to conventional Fe and NFe coating measurement, making galvanized steel an important application area for these instruments. What Is Galvanized Steel? Galvanized steel is steel that has been coated with zinc to help protect the underlying steel against corrosion. A simplified layer structure is: Steel substrate → Zinc layer The zinc acts as a protective layer between the steel and the surrounding environment. Galvanized products are commonly found in: Structural steel Steel fabrication Outdoor equipment Fencing Handrails Electrical installations Cable support systems Roofing components Industrial structures Steel frames Utility infrastructure Some galvanized products receive an additional paint or powder coating over the zinc layer. The structure can then become: Steel → Zinc → Paint / Powder Coating This makes measurement more complicated than ordinary paint directly over bare steel. Why Is Galvanized Steel Different for a Coating Thickness Gauge? A conventional Fe coating thickness measurement is commonly used for a suitable non-magnetic coating over a ferrous steel substrate. For example: Steel → Paint or: Steel → Powder Coating Galvanized steel introduces another metallic layer: Steel → Zinc If paint is added: Steel → Zinc → Paint Therefore, users should not simply assume that every coating thickness gauge will distinguish each individual layer automatically. Before selecting an instrument, determine exactly which layer needs to be measured. What Does Fe+Zn Mean? The TASI TA521A and TA522A include a dedicated Fe+Zn measurement capability. According to TASI specifications, the Fe+Zn range is: 3500 μm This feature is particularly relevant when galvanized steel needs to be evaluated. It gives the TA521A and TA522A an additional application beyond conventional Fe/NFe paint thickness measurement. For companies working with galvanized products, this is an important feature to consider when comparing coating thickness gauges. TASI TA521A / TA522A Measurement Capabilities The series provides: General measurement range: 02000 μm Accuracy: ±(3% + 1 μm) Fe magnetic induction measurement NFe eddy current measurement Automatic substrate recognition Fe+Zn measurement capability Fe+Zn range: 3500 μm Zero calibration μm / mm / mil measurement units 2 readings per second 180° screen rotation The TA522A additionally provides manual measurement mode selection, making it our preferred option for users performing regular professional measurements. Where Is Fe+Zn Measurement Useful? Potential applications include companies involved in: Galvanizing Steel fabrication Structural steel Engineering Metal finishing Manufacturing Construction Infrastructure Quality control Incoming inspection Supplier inspection For these users, zinc coating thickness may be part of product quality or corrosion-protection requirements. Galvanized Steel Incoming Inspection Consider a manufacturer purchasing galvanized steel components from an external supplier. Instead of relying only on supplier documentation or visual appearance, the company's QC team may want to perform its own incoming checks. A typical workflow could be: Supplier → Galvanized Component → Incoming QC → Thickness Measurement → Acceptance Measurements can be taken at predetermined locations and recorded as part of the inspection process. The acceptance criteria should be based on the relevant purchase specification, product requirement or applicable standard. Galvanized Steel for Outdoor Applications Galvanized components are commonly selected where corrosion resistance is important. Examples can include: Outdoor steel structures Handrails Fencing Support frames Platforms Utility structures Equipment supports Building components The zinc layer plays an important role in corrosion protection. Measuring coating thickness can therefore provide useful information during manufacturing or inspection when thickness requirements have been specified. Paint Over Galvanized Steel This is where users need to be particularly careful. Suppose you have: Steel → Zinc → Paint What do you want to know? Do you want: A. Zinc thickness? B. Paint thickness? C. Total coating thickness? These are not necessarily the same measurement requirement. Do not assume that a basic coating thickness reading automatically separates multiple coating layers. If your application involves paint or powder coating over galvanized steel, provide the complete layer structure when selecting the instrument. This helps avoid buying a gauge based on an incorrect assumption about what the displayed reading represents. Why This Matters for Powder Coating Companies Powder coating companies may receive galvanized components from customers. If the operator treats galvanized steel exactly like bare steel without understanding the substrate structure, measurement interpretation may become confusing. The first question should therefore be: What is underneath the powder coating? Bare steel? Aluminium? Galvanized steel? The answer affects how the measurement should be approached. TA521A vs TA522A for Galvanized Steel Both the TASI TA521A and TA522A include Fe+Zn capability. Both also provide: Fe measurement NFe measurement 02000 μm general measuring range ±(3% + 1 μm) stated accuracy Automatic substrate recognition For occasional general measurements, the TA521A can be considered. For factories, steel fabricators, galvanizing-related users and QC teams performing repetitive inspections, we generally prefer the TA522A because it provides additional manual measurement mode control. The TA522A is not more accurate according to the stated core accuracy specification. Its advantage is greater operating flexibility. Galvanized Coating Thickness vs Paint Thickness These two terms should not be confused. Galvanized coating thickness generally concerns the zinc coating associated with the galvanized steel. Paint thickness concerns the paint or coating system applied over a substrate. When both zinc and paint are present, the measurement requirement becomes more specific. This is why customers looking for a coating thickness gauge should describe their actual sample rather than simply asking: “Can this measure galvanized steel?” A better description is: “We have galvanized steel with powder coating on top, and we need to measure ______.” That allows the supplier to assess the application correctly. Should You Measure More Than One Point? Yes, when meaningful inspection is required. Coating thickness can vary across a component. Depending on the product and applicable inspection procedure, measurements may be taken at: Multiple faces Different positions Edges Centre areas Different components from the same batch For repetitive QC, using consistent measurement locations can also help identify process changes over time. Common Buying Mistakes Assuming Fe+Zn Is the Same as Ordinary Fe Measurement Galvanized steel introduces a zinc layer over the ferrous substrate. Understand the instrument's intended measurement mode before interpreting results. Not Describing the Layer Structure Tell the instrument supplier whether the sample is: Steel + Zinc or: Steel + Zinc + Paint or: Steel + Zinc + Powder Coating Assuming Every Gauge Can Separate Multiple Layers Do not assume a general coating thickness gauge can independently display the thickness of every layer in a multilayer coating system. Buying Only by Maximum Range Measurement principle and application compatibility are just as important as maximum thickness range. FAQ Can a coating thickness gauge measure galvanized steel? Some instruments are specifically designed with measurement capabilities relevant to galvanized steel. The TASI TA521A and TA522A include an Fe+Zn measurement mode. What is the TASI Fe+Zn measurement range? TASI specifies an Fe+Zn range of 3500 μm for the TA521A/TA522A series. Can TA522A measure zinc coating on steel? The TA522A includes Fe+Zn capability. The exact suitability should be confirmed against the galvanized product, layer structure and required inspection method. Can TA522A measure paint on galvanized steel? Applications involving steel + zinc + paint should be assessed carefully because multiple layers are involved. Tell MTM Precision exactly which layer or thickness value you need to determine. Can TA522A measure ordinary paint on steel? Yes. It supports magnetic induction measurement for suitable coatings over ferrous substrates. What is the difference between Fe and Fe+Zn? Fe measurement is used for suitable coating measurements over ferrous substrates. Fe+Zn is specifically relevant to applications involving zinc-coated ferrous substrates. Which is better for professional use, TA521A or TA522A? Both provide similar core measurement specifications and Fe+Zn capability. We generally recommend the TA522A for professional repetitive work because of its additional measurement mode control. Looking for a Galvanized Steel Coating Thickness Gauge in Malaysia? If you need to inspect galvanized steel, do not select an instrument based only on the words “coating thickness gauge.” Tell us your actual layer structure: Steel → Zinc or Steel → Zinc → Paint or Steel → Zinc → Powder Coating and tell us which thickness you need to measure. MTM Precision can help evaluate the application and recommend a suitable coating thickness instrument, including the TASI TA521A and TA522A. Contact MTM Precision MTM Precision Sdn Bhd No. 29-1 & 29-2, Jalan Bandar 18 Pusat Bandar Puchong 47160 Puchong, Selangor, Malaysia Website: www.mtmpre.com.my WhatsApp: +6016-660 7346 Email: mtmpre@yahoo.com