Where the
world gathers for metal finishing
Q&As since 1989


-----

Constant Colour Anodizing

Can anybody advice, how to keep a constant colour scheme for colour anodizing.

Leon Chua
- Singapore
2000

---

2000

Leon Chua

You did not state process so I guess I'll give you some of the 1st points for me to trouble shoot

• Anodize solution temperature
• Anodize thickness
• Dye Temperature
• Dye Concentration
• Rinse after anodize
• Amount of dissolved Aluminium in Anodize solution

With the black dyes most of my trouble was associated with Thickness of coatings With the lighter coating it was with the dye temperature

Chris Snyder
plater - Charlotte, North Carolina

Why not control measure the color on-line?

Joseph K. Price
- Morganton, NC USA
2000

---

Measuring the color on line does sound interesting, but what does Mr. Chua do with the color information he measures and records, that will move him from the point of talking about the weather to doing something about it?

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2000

Color matching of anodize is an art. The best way to do it I have found is to allow for the variations of temperature concentrations, etc., but it is painstaking. First establish min/max color chips with your customer. Second, run one rack of parts by hand after anodize through the color dye and seal to match nominal between color chips. Record the times in dye and seals, then immediately run the rest of your racks identically to the first. The next load will require exactly the same procedure because in the span of time between the last load and the present one, things will change. Remember, that for this to work you must first have a correctly sized anode to cathode ratio for your anodize load and your concentrations in all tanks must be kept as constant as possible, including dyes and seals.The thickness and density of the preceding anodize coating must be kept as close as possible prior to the dye cycle. This matching process will allow for minor variations in your dye and seals pHs, temps etc by changing the immersion times from load to load to match color shades.Actually, trickier than it sounds.

Ward Barcafer, CEF
aerospace - Wichita, Kansas
2000