LCD method

[SX Paintball]

I have been anodizing for a while now the "old" method. Just wondering about the LCD method. I have a 15-gallon acid bath with a 1-3 acid to water ratio, I keep the temperature around 70 degrees. I run 7 amps per square foot of part area; most runs are about 125 mins per complete paintball gun. From my understanding, the LCD runs at lower amps per square foot. However, I cannot find any info on the method. Most of my results are good, however I get a few parts that look darker "burnt", just wondering if I used a different method, I might get results that are more consistent. Any info would be greatly appreciated.
Thanks,
Shane

[sswee]

The LCD method is in the Caswell plating manual.
If you're using a 1:3 acid ratio and only 7 ASF your not far off the LCD method. Are you using CV or CC power? This is one of the most important things for consistency. I've seen your pics and you look like you've got it down. The problems are probably just in the details. I use a little higher CD's to get run times down and consistency is not a problem.
SS

[SX Paintball]

I use a rectifier with adjustable volts and adjustable amps, up to 14 volts and up to 25 amps. I was just wondering if everyone here uses the LCD method? and what current density everyone uses?

Thanks again,
Shane

[acidrain]

We all use the LCD method... I'm running 6 amps per sq. ft.
Are you familiar with the 720 rule? There is a stickied thread describing it above, and about 8 posts in, there is a calculator, which figures out required amps and time to build the desired mils.
If you are having one or two parts in a batch that are not turning out well, it may be that they are a different alloy.
I seperate out the different alloys, and run the 5xxx and 6xxx for full time, but run the 2xxx and 7xxx for 3/4 time.

[SX Paintball]

Yes I use the 720 rule now, I use to use the 900 rule a few years ago. I never have very much patiences figuring out sq. ft of parts though. So the LCD method is around 6 amps per sq. ft?

Acidrain, I seen some photo's of your ano tank, what do you use for air agitaion? I use two fish tank air pumps hooked up on each side of the same plastic tube running around the bottom of my tank. Another question, what distance should parts be away from the cathodes?

Thanks again everyone,
Shane

[acidrain]

My air source is actually my big industrial air compressor with a good in-line filter. I built a CPVC manifold with 1/16in holes drilled every 4in or so. I regulate the air down to about 20psi line pressure, then regulate it again at the tank to control the bubbles.
I run at 6 amps CD... there are advantages to LCD: low heat accumulation, low fumes, good color absorbtion, and clear parts come out silver... not yellow.
I try to stay at least 3 inches away from the cathode.
GL!

[SX Paintball]

I have very little air agitation, I think that might be my biggest problem right now. I think the parts that are getting the burnt look are usually in the middle of my tank where there is no agitation. I seen the photo of your tank in action and wow, it was bubbling like crazy. I never knew you could have that much movement in the ano tank. So, right now I am looking for a small compressor and to rebuilt my air lines.

Thanks everyone,
Shane