Anodizing Process

SURFACE PREPARATION

Anodizing Process Tank Sequence

Tank	Process	Temp F	Material	Equipment	Comments
1	Soak Clean	140	Steel or Polypropylene	Heater (Steel or SS)	Optional vent water vapor
2	Cold Water Rinse	Ambient	Steel or Polypropylene		Bottom fed, continuously overflowing
3	Alkaline Etch	140	Steel or Polypropylene	Heater (Steel or SS)	Vent hydrogen bubbles coated with caustic
4	Cold Water Rinse	Ambient	Steel or Polypropylene		Bottom fed, continuously overflowing
5	Deoxidizer Desmut	Ambient	Polypropylene or PVC		Air Agitate
6	Double Cold Water Rinse	Ambient	Polypropylene or PVC		Air Agitate
ANODIZE
7	Anodize, sulfuric	25 to 72	Polypropylene or PVC, some use lead	Chiller, Heat Exchanger, Rectifier	Air Agitate, vent hydrogen bubbles coated with sulfuric acid. Chill against wattage input of d.c.power supply
8	Cold Water Rinse	Ambient	Polypropylene or PVC		Air Agitate, bottom fed, continuously overflowing
9	5% Nitric Acid	Ambient	PVC, but many use Polypropylene		Change frequently because sulfate builds up.
10	Cold Water Rinse	Ambient	Polypropylene or PVC		Air Agitate, may cascade to Tank 8
11	Dye	140	Polypropylene, PVC, or stainless steel	Heater (Steel or SS)	Air Agitate. If stainless steel insulate the load bar. May have galvanic problems with stainless steel
12	Cold Water Rinse	Ambient	Polypropylene or PVC		Two rinses preferred, plus another for each different dye color
13	Seal	180- 212	Stainless Steel	Heater (Steel or SS)	Random Air Agitate
14	Hot Water Rinse	205	Stainless Steel	Heater (Steel or SS)	Change Frequently
CHROMATE
7	Chromate	Ambient	Polypropylene or PVC		Moderate Air Agitate
8	Stagnant Cold Water Rinse	Ambient	Polypropylene or PVC		See Figure 3-3
9	Stagnant Cold Water Rinse	Ambient	Polypropylene or PVC
10	Stagnant Cold Water Rinse	Ambient	Polypropylene or PVC