[neilfj]

Edited parts of the 720 Rule Formula which I originally posted incorrectly

Originally Posted by blackcote

Before I get started.... what does high sulfur content in tap water do to the acid solution?

I don't know specifically what chemical reaction may take place. It could range from nothing to creating sulphur dioxide (rotten eggs). Generally speaking, any contaminate in the electrolyte can interfere with the conductivity of the solution, interfere with the chemical reaction, or both.
The reason distilled water is specified is to eliminate the potential of any contaminate causing problems. This is also true with the stripper, de-ox/de-smut, sealer and dye. It is difficult to control reactions when unknown elements are added to the mix. The reaction of the chemicals in the tap water can cause spotting, discoloration, brittleness of the surface, incorporation of other chemicals into the structure of the anodized cells, and generally all kinds of issues. Your specific problem may not be due to the use of tap water, but as a general practice its use should be discontinued.

dip part in ano stripper for a minute or two.
rinse w/ tap water
dip part in de-ox de smut for a few seconds
rinse w/ tap water
anodize part (.06 SF) in 1:2 acid to tap water for 45 min at 30A/SF (I was guessing that it needed to be anodized twice as long but didn't want to wait that long) Part came out looking similar to what it should (not silver or light grey)
rins w/ tap water
soak in dye for 20 min at 140F
hmmmm looks better but still not good nice dark grey color
now here's the kicker.
I stuck it back in the anodize at 60A/SF for 15 min
went through the same process and got a beautiful jet black color
sealed it for 15 min... minimal dye came off the part and it stayed black
wohooo one good part in 2 weeks... too bad it was a sample.

How are you making the connection? At .06 SF, I suspect you may have a connection problem. Being such a small piece makes it difficult to get a good connection.

i give up at this point and decide to do some other parts. mat'l was unknown. I was told either 6000 series or 7000 series... gee thanks for the help on that one. So I put 4 pieces in totalling .66SF set amps at 11 for a little fudge factor over 15ASF since I'm getting crappy results anyway. Consistent... but crappy. Well it started at 73ish degrees... till I got to my 45 min It was at 85 degrees Didn't even cross my mind about heating the solution too fast. They were med to dark grey coming out of the acid. i rinsed and died anyway and they were then dark grey and the dye really didn't take all that well. Is this what typically happens when you get past the 78 deg mark?

Yes. The higher temp increases the speed at which the anodizing layer is eaten away by the acid. The acid eats away at the cell structure of the layer until the cell is so large, it won't hold the dye well.

Before you spend any more money, would you be will to send me a sample or two of what you are attempting to anodize? I doesn't have to be a machined piece, just a piece the approx. size and of the same material you are attempting to anodize. I just finished an anodizing test yesterday and I'm still set up. I'd be willing to give it a shot and let you know what works. I should be able to turn it around in a couple days. Let me know if this will work for you and I'll send you my address.

Sometimes I hate being stubborn and keep at a challenge till I get it.

I know exactly what you mean...Ask Fibergeek about how stubborn I am!

Anodizing at 30-60amp/sq ft? WOW! {edited}[b]We're use to lower currents, but some of the basic rules should still apply. At 30 amps the sample should be in the electrolyte for {edited} 24 minutes based on the 720 rule for a 1 mil thickness. Having it in for 45 minutes may be too long and it may be opening the pore structure so that the dye doesn't absorb. At 60 amp density, it should be in for 12 minutes. Your 15 minutes probably didn't make much of a difference..

Edited to add:

I'm currently set up for the LCD method. I can run the test and get the samples back to you so you can see how well it works. As Ford said, any color can be ordered, as long as it is black (since I only have the black dye).