news — from the mill.
Production notes, industry updates, and a little colour on what we’re making this month.
PPGI Coil Gloss Levels: 20%, 30%, 70% Specification Guide
When specifying a prepainted galvanized iron (PPGI) coil, the gloss level is not merely an aesthetic afterthought; it is a functional specification that affects light reflection, surface temperature, dirt visibility, and formability. The short answer to the buyer question is: choose 20–30% gloss for most roofing and wall cladding panels where glare reduction and surface […]
Read →PPGI Coil for Roofing Sheet Profile Compatibility
To prevent cracking or failure when forming your specific roofing profile, you must match three PPGI coil properties to your roll former: yield strength, total elongation, and paint system flexibility. A coil that is too strong or whose paint film is too brittle will micro-crack at tight bends; a coil that is too soft may […]
Read →PPGI Coil Blistering: Causes, Prevention, and Inspection Guide
Blistering on your PPGI coil’s surface is almost always a sign that localized adhesion has failed between the paint film and the substrate, or between coating layers. In practical terms, a blister is a small, dome-shaped elevation of the paint film caused by trapped moisture, solvent, air, or gas. If you are seeing blisters, the […]
Read →PPGI Coil Coating Adhesion Cross Hatch Test: Incoming Inspection Guide
Yes, you can add a simple, effective adhesion test to your incoming inspection process for PPGI coils. The cross-hatch (or cross-cut) test is a standardized method for evaluating how well the paint film adheres to the metallic substrate. This guide explains how to perform it correctly, interpret the results using the 0B to 5B classification […]
Read →PPGI vs GI Sheet: When Is the Extra Cost for Prepainted Steel Justified?
If you are covering a large warehouse area, the initial cost of bare galvanized (GI) sheets is undeniably lower than that of prepainted (PPGI) coils. However, the true financial comparison is not the purchase price per ton; it is the total cost of achieving a durable, finished, and weather-resistant roof over a 10-year period. In […]
Read →PPGI Coil 20-Year Warranty: Claim Conditions and Exclusions
When a supplier offers a 20-year warranty on PPGI coils, the fine print determines whether that promise has real value or is merely marketing language. In practice, a 20-year warranty typically covers only specific failure modes—such as corrosion penetration through the metallic coating or premature paint degradation—under strictly defined environmental and installation conditions. To file […]
Read →PPGI Coil Quality Checks: Pencil Hardness and T-Bend Testing Guide
Yes, you can perform meaningful pencil hardness and T-bend tests in your own warehouse to verify that incoming PPGI coils match the coating properties stated on the mill test certificate. These two tests are practical, low-cost, and require only basic hand tools. However, they are screening tools, not full laboratory certifications. To get reliable results, […]
Read →PPGI Coil Color Change After Bending: Stress Whitening Explained
Yes, the whitish or lighter color you see at the bend lines of your PPGI sheets is most likely a physical response of the paint film to stress, not a manufacturing defect in the coating itself. This phenomenon, commonly called stress whitening, occurs when the paint film is deformed beyond its elastic limit during forming. […]
Read →PPGI Coil Roll Forming: Oil Pickup and Coating Damage Prevention
Yes, the forming oil you use can interact directly with the paint system, and it is often the primary trigger for scratches and peeling—but it is rarely the only cause. Coating damage during roll forming is typically a combined result of lubricant chemistry, paint film hardness, metallic coating topography, and tooling setup. You cannot rule […]
Read →Why the Back Side of PPGI Coil Matters: Primer and Back Paint
When you order PPGI coils for roofing sheets in a humid climate, the back paint is not a cosmetic detail—it is a corrosion-control decision. The functional difference between epoxy, polyester, and primer-only systems is about moisture barrier performance, adhesion to the metallic coating, and formability. In short: a well-specified reverse-side coating can delay edge and […]
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