news — from the mill.
Production notes, industry updates, and a little colour on what we’re making this month.
PPGI for Sandwich Panel Facing and Foam Bonding
For most sandwich panel lines, the facing that bonds most reliably is a prepainted galvanized or galvalume steel coil with a thin, chemically compatible back coat (often a polyester or epoxy-based primer, or a PU-friendly primer specified by the adhesive supplier), a controlled surface treatment such as a chromate-free or Cr(VI)-free passivation plus a primer, […]
Read →PPGI Roll Forming Coating Adhesion and Cracking Defects
If your PPGI coating is cracking, flaking or losing adhesion during roll forming, the cause is almost always a mismatch between three things: the paint system’s flexibility, the forming severity (bend radius, T-bend, impact), and the line setup (tooling condition, speed, temperature). Coating failure is rarely a single-variable problem. A coil that passes a flat-sheet […]
Read →PPGI Thickness and Width Tolerance Standards
For most PPGI coil deliveries, the practical answer is: accept thickness only within the tolerance band your purchase order states, applied to the uncoated steel base (not the painted total), and accept width within the ordered width plus/minus the agreed edge allowance — commonly a minus-only band for slitting and a plus/minus band for mill […]
Read →PPGI Zinc Coating Mass: Z100 to Z275 Substrate Guide
For most prepainted applications, the galvanized base should be specified by zinc coating mass per unit area of the finished sheet, not by a single “best” Z number. As a starting rule: Z100–Z120 suits mild, sheltered, short-service or cost-driven panels; Z180–Z275 suits cut-edge exposure, humid or coastal atmospheres, heavier forming, or longer expected service. The […]
Read →PPGI Color and Gloss Tolerance: Delta E Control Guide
For most PPGI coil orders, a reasonable commercial target is a color difference (Delta E) of about 1.0 or less against an approved master panel, with 1.5 as an upper acceptance limit for production batches, and a gloss tolerance of roughly ±5 gloss units when the nominal gloss is 30–70 GU. These are common starting […]
Read →PPGI Price Drivers and Quotation Inputs: A Buyer’s Cost Model
Your PPGI coil quotation changed between two inquiries because at least one specification input changed — or because the mill’s cost base moved between the two dates. PPGI (prepainted galvanized steel) is not a single product with a single price; it is a configuration. Substrate grade, zinc coating mass, paint system, film thickness, coil dimensions, […]
Read →PPGI Gloss Control and Color Matching Tolerances
Between PPGI coil batches, a gloss variation of roughly ±5 units at 60° and a color difference of ΔE ≤ 1.0 to 2.0 are commonly achievable targets for solid colors under a defined measurement method — but the exact figure must be agreed in writing, because “normal” variation depends on paint system, color depth, substrate, […]
Read →PPGI Substrate Steel Grades: DX51D, S250GD, S350GD
If your PPGI coil will be roll formed into roofing and cladding sheets, the substrate is usually a low-carbon, fully killed, continuously cast steel with a nominal yield strength around 140–180 MPa and excellent elongation — most commonly DX51D, or S250GD where a defined minimum yield is required. If the painted panel is acting as […]
Read →PPGI Zinc Coating Weight vs Paint Performance
Does a heavier zinc coating always mean longer PPGI service life? No — not by itself. Zinc coating mass (commonly specified from Z100 to Z275, and in some markets as G30 to G90) mainly controls how long the metallic barrier survives after the paint film is breached. Paint performance under normal exposure depends more on […]
Read →PPGI Paint Adhesion Testing: Methods and Failure Analysis
To verify paint adhesion on PPGI coil before shipment, request the mill’s test records for T-bend, cross-hatch, impact and cupping, then confirm that the same test methods, sample location and acceptance values are written into your purchase order. Each test loads the coating differently: T-bend measures flexibility over a tight radius, cross-hatch measures resistance to […]
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