Summers FinishingSURFACE FINISHING · SYDNEY
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Sulfuric acid anodising

Type II anodise.

Conventional sulfuric acid anodising of aluminium and aluminium alloys to MIL-A-8625F — Class 1 clear or Class 2 dyed, sealed for corrosion resistance or unsealed ready for paint.

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FIG. 01Sulfuric acid anodising line · Wetherill ParkMIL-A-8625F · TYPE II · CL 1 & 2
The process

Grown from the metal, not laid on top.

Type II anodising is a conversion coating which converts the aluminium surface itself into a porous ceramic oxide layer.  Grown electrolytically in a sulfuric acid bath, dyed if specified and sealed to lock in corrosion resistance.

Our in-house software programs the rectifier per load, calculating surface area, then holding current density inside the window our process control document sets for each alloy series - Same coating everytime. Film builds of 1.8–25 μm to drawing callout.

CLASSES · MIL-A-8625FSEALED UNLESS OTHERWISE SPECIFIED
CLASS 1

Non-dyed

Clear anodise — the natural oxide colour of the alloy. Corrosion protection, paint base and cosmetic uniformity without pigment.

CLASS 2

Dyed

Uniformly dyed before sealing — black and colours to drawing callout, with light-fastness testing when the contract specifies it.

Quality control

Verified as MIL-SPEC demands.

№TestMethodAcceptanceFrequency
01Visual & dimensionalVisual examination · dimensional checkContinuous, smooth, adherent coating — no powdery areas, breaks or scratches; drawing dimensions held after coatingEVERY LOT
02Coating weightASTM B137 ≥1000 mg/ft² for Type IIMONTHLY · ≤35 DAYS
03Salt spray corrosionASTM B117 ≤15 pits per 150 in² across ≥5 panels, ≤5 pits per 30 in², none >0.031 inMONTHLY · ≤35 DAYS
04Light fastnessClass 2 dyedFading no greater than ΔE = 3AS REQUIRED
05Paint adhesionFED-STD-141No intercoat separation, paint-to-coating or coating-to-metalAS REQUIRED
06Solution analysisPer process control documentAll line solutions within PCD control ranges · full bath history retainedFORTNIGHTLY

PROCESS CONTROL FAILURE HALTS PRODUCTION · TRACEABLE WORK QUARANTINED UNTIL CAUSE IS CORRECTED

Applications

Where Type II is called out.

MARINE & GSE HARDWARECORROSION PROTECTION
ENCLOSURES, PANELS & HOUSINGSCOSMETIC DYED
PARTS UNDER PAINT & PRIMERADHESION BASE
OPTICS & INSTRUMENT BODIESSEAL BANDS
IDENTIFICATION & NAMEPLATESLASER ENGRAING
ANODIC COATING · 12 μm TYPICAL ALUMINIUM OXIDE · TYPE II · 1.8–25 μm RANGE ~6 μm GROWTH ABOVE ORIGINAL SURFACE ORIGINAL SURFACE ~6 μm INGRESS INTO THE SUBSTRATE ALUMINIUM SUBSTRATE TYPE II · 12 μm TYPICAL FILM — DIMENSIONAL GROWTH ~6 μm PER SURFACE · MINIMAL CHANGE
FIG. 02 · COATING GROWTH · TYPE II AT 12 μm