Coatings

Choose chem film when you need electrical conductivity, minimal dimensional change, or a paint/powder base at low cost; choose anodize when you need real wear resistance, a harder surface, dyed cosmetics, or dielectric behavior. Chem film is a thin conversion coating measured in millionths of an inch, while anodize is a grown oxide measured in ten-thousandths. Many parts combine them – anodize overall with chem-filmed masked pads for grounding.

Yes – that is one of their primary jobs: chem film per MIL-DTL-5541 (or anodize) provides the corrosion-resistant, adherent base that paint and powder need on aluminum, and phosphate or appropriate pretreatments serve the same role on steel. Skipping the conversion layer is a common root cause of coating adhesion failures in the field. Specify the pretreatment on the drawing alongside the topcoat rather than leaving it to the paint shop.

Yes – when the metal finish and the organic topcoat run under one purchase order, the handoff timing between pretreatment and painting is controlled (fresh chem film paints better than aged), there is a single quality system accountable for adhesion, and there is no freight or scheduling gap between shops. Gleco pairs its plating and conversion coating lines with powder coating, wet paint, and Cerakote through its Paint & Powder division, so multi-finish parts stay in-house. That also means one cert package covering the whole finish stack.

The main drivers are line compatibility (whether your spec and bath chemistry are already running), masking complexity, required testing such as salt spray with defined durations, lot size versus rack or barrel capacity, and how complete the PO callout is – clarification requests are the most common avoidable delay. Certified test requirements add fixed days regardless of shop speed. Sending the full drawing with spec revisions at quote time is the single best thing a buyer can do for lead time.

If the surface must carry current or provide EMI grounding, that requirement filters the field first: chem film Class 3 on aluminum, or tin, silver, or nickel plating, all preserve conductivity, while anodize and painted finishes are insulating. If corrosion life dominates and conductivity is irrelevant, thicker barrier or sacrificial systems win. When a part needs both, split the requirement by zone with masking and put both callouts on the drawing.