need help

[Batman]

I'm having color issues I'm pretty new at this and still in the dark about how to figure out my current density. I've been trying to get a nice polished black but I keep getting bloches in the color. I use distilled water for everything and rinse well between steps. I thought it might have been the polish I am using (just some regular red rouge from the hardware store). I using soap and hot water as well as a hot cleaner solution before anodizing and a desmut/deox. my smaller parts turn out fine but these frames always have bloches whats happening? I've tried leaving the parts in for 40 minutes 1hr and 1.5 hrs and still the same result. using a cc/cv power supply I leave everything at zero then slowly crank up the volts to max then amps to 5 and leave it volts go down but amps stay the same as time goes on. any ideas?

[acidrain]

First off, you are having problems figuring out the amps? Let's work on that first. You have to carefully measure the surface area. It's a pain, but it's important. Measure the surface area in sq. inches, divide by 144 (sq. in. in a sq. ft.), multiply by your current density (somewhere between 4.5 and 6 amps per sq. ft.... I use 6), use the 720 rule calculator and enter the mils (go for 1mil with black).
Example: 65 sq. in. divided by 144 = .45 sq. ft. X 6CD = 2.7amps X 2 hrs. = 1mil.
All things equal, and some parts turn out good, and others don't, I suspect you are anodizing a mixed alloy batch.
2xxx and 7xxx alloys require less time than 5xxx and 6xxx alloys (I know, it's not in the 720 rule calculator).
I can tell you with careful experimentation I have discovered that 3/4 of the time is all you need for the 2xxx and 7xxx alloys.
How can you tell what the alloy is? When you strip the parts, do they turn dark gray or black? If so, they are 2xxx or 7xxx.
I divide up the different alloys and run all the 5xxx and 6xxx (the ones that stay silver after stripping) together for full time.
Then I run all the 2xxx and 7xxx together for 3/4 of the time.
Also, you'll find the gloss retention is much better, and the colors will match better.
Oh, and do yourself a favor and get some Caswell's SP degreaser. You'll still need to get all the compound off first (I use lacquer thinner, then soap and water), but just a quick dip in 140F degreaser will pretty much guarantee a contaminant free surface. Be aware though, it will dull the surface if left in too long.
Using the CC PS, start by turning the volts all the way up, and the amps all the way down, then turn it on and slowly ramp up to the required amps.
Once you get all dialed in and have good consistent results, I can teach you a way to start in CV, then switch to CC 5 minutes into the run which will skip the measuring surface area step.