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[acidrain]

I agree with cameraman's first impressions... I question the 4 hr run time.
I ano at 6 amps per sq. ft, and it takes 2 hrs for a 1mil build.
3 amps per sq. ft. would require 4 hrs for a 1 mil. build
1.5 amps per sq. ft. for 4 hrs for a .5mil build.
You should not ano at less than 3 amps per sq. ft... 4.5 amps per sq. ft is what I would consider the lowest CD.
How many sq. inches of surface area were your parts?

[larryp]

Ah hah, it's a lost day when one doesn't learn something. Did not know that low cd could do that. Water break test was performed satisfactorily. I will run higher level current today and let you know result this evening. Thanks, Larry

[larryp]

My apology to cameraman, I did not thank you for your input yesterday. Sorry. Results of 7/21 work were: the power supply will output appx 1amp on a 40 in2 sample and appx 4amp on a 160 in2 sample. As cameraman said the other day the power supply does not have the proper characteristics for this work but I have to see if I can make do with it for a while. The test samples had nonconductive film but took no dye to speak of. Both samples ran 45 minutes. I'll let you know what transpires next. Thanks to all, Larry

[larryp]

I ran some parts with 1.21 ft2 area @ 5a for 2hr 55 min. The color was a nice deep black, but again had sooty deposit. Bath temp being controlled with the chill system implemented last week. This time when I took the parts out of dye I wiped some areas on a couple with my finger and then rinsed again , those areas had virtually no deposit after they came out of sealer. Dye wrong?, ano bath wrong? I read a post by Mike Caswell where he gave proper PH for dye but how do you check and adjust? It appears that WD40 is the conventional method to pretty up a poor finish, what does it do long term? Hope everybody had a good weekend, I had fun and games erecting a steel building. The good luck was, it is a pool house for a buddy, guess where we ended up? Thanks, Larry

[acidrain]

I checked your calcs, and they seam right on. A bit low on the CD of a little over 4 amps per sq. ft., but should be good.
I doubt it has anything to do with the PH of your dye, but if you search, there are threads on this subject. You'll need a digital PH meter (available on ebay for ~$20).
What is the alloy of your part? I suspect maybe it is an off alloy that soots after extended anodizing.
I would run the exact same part, same parameters, only stop the run at 2 hrs for a .75mil build. Then dye it black, and see how it looks. If the dye is deep black, you were over anodizing for that alloy.
One last thought... is your sealer mixed at the correct ratio? Mixed with distilled or RO water? Boiled (or near boiling) for 30 minutes?
How about the dye... 140F for 15 minutes? Mixed at the correct ratio with distilled or RO water?
We'll get this yet.

[larryp]

acidrain, Can do on PH meter but how do I adjust PH if wrong ? The alloy of parts are 6061-T651 or T6, material is purchased from reputable distributor with matl certs. I'll try the two hour run today. Sealer mixed at correct ratio, distilled water used for initial make up and all susequent addtions for evaporative loss have been with distilled water. Initial rinse water is tap water then part is rinsed with distilled water from spray bottle to prevent drag in of tap water. Sealer runs at 180* for 20 min. per mfg. directions. Same water and concentration comments for dye bath. Dye bath runs 140* for 15 min. Thanks many times for your help. Larry

[cameraman]

The shorter run time is a good idea, and you might read up on the constant voltage method if you're still using that same power supply.
Use ammonia to raise the pH and diluted acid to lower it - only add a few drops at a time.

[larryp]

The 2 hr ano time results were no soot, good color but not as black as previous. Still plenty black. Which raises a question about how black is black? You see how my mind runs, worries me some times. Unfortunately there was a non-dyed area on exterior surface, probably due to me not rinsing thoroughly, I stripped the lot and will ano again tomorrow Anyway, seem to be on the right track thanks to you guys’ guidance. Cameraman, you said to adjust PH with ammonia or acid. What kind of acid? Since I have been the recipient of ya'lls knowledge I would like to share something I learned today. Of course you probably already know. The parts I ran yesterday had dull areas after rubbing up with cloth, then WD 40. Wound up having at them with Mothers Mag Polish. The surface looks like they have been powder coated. Almost no effort required getting a mirror like surface. I can't thank ya'll enough. Larry

[acidrain]

Nice... glad to hear things are improving.

[cameraman]

If it's not as black as you'd like then you probably grew a layer that's thinner than you might want for your application but successfully avoided dissolution. More importantly, you achieved proof of concept (the 'larryp's back up on the roadway' concept) - a little more tweaking and you'll have it nailed.

You can use acetic acid or the battery acid for pH adjustments - I've not had to adjust my dyes' pHs yet, I'm getting this info from:
http://forum.caswellplating.com/show...6387#post16387

which blackcote had pasted into the sticky thread 'Anodizing Dye pH' near the top of the forum.

In it they're talking about lab grade acetic acid - personally I think I'd just use white vinegar or some fresh 3:1 instead of chasing down lab stuff, but there could be reasons that lab grade is more preferable...