Weird results with red dyes

[sawtoothrc]

I don't know if anyone here has ever had this problem, but has become a recurring one that I have not been able to solve.

This is my third batch of red dye in about a month, for some reason when I get new red dye I can do 3 or 4 batches, and then something happens and the parts look washed out, like in the picture.

But I also do blue, purple and black parts in the EXACT same way, and have never had a problem.

I use separate Stainless steel pots for each color, and also for the sealant for each color. The batch in the picture failed yesterday, so today I stripped and re did them; now they are worse.

I've not only replaced the dye, but after I started gettting bad parts with the second bottle of red, I replaced both the dye pot and the sealant pot and started out with fresh dye and sealant. Then my 3rd and 4th batch looked like the parts picture, and I cannot figure out why.

Does anyone have any suggestions/ideas?

Sorry for the huge picture size, but I wanted to be sure it be could seen clearly.

[NeoMoses]

Well, a couple of questions:

1. how are your electrodes attached?
2. What is your surface prep? Have you tried bead blasting any parts right before anodizing?
3. How large and where is your cathode?
4. Do you have any type of aeration/agitation?


That looks similar to some of the problems that I've seen, but it appears to be very repeatable among the pieces of the same geometry, like the circular pieces... I haven't seen that before.

[sawtoothrc]

Well, a couple of questions:

1. how are your electrodes attached?

Not sure exactly what you are referring to...

2. What is your surface prep? Have you tried bead blasting any parts right before anodizing?

No surface prep, aside from the degreasing. And no bead blasting.

3. How large and where is your cathode?

I built a C- shaped bracket out of Titaniam, and hang one 1" * 6" lead strip on each side of the rack in the tank.

4. Do you have any type of aeration/agitation?

No. I tried it but it made no difference.

The thing that is weird is that I still do hundreds of parts in Black, Purple and Blue the EXACT same way, but have never once had this occur. If there was something wrong with my process or setup up it would happen with all colors, not just the Red, wouldn't it?

I changed the tanks and dye in case it had gotten contaminated, but after 3 batches it was occurring again. And there was an oily looking film on all three batches of red dye, but I have never seen it on any of the other colors.

When it first happened, I even went so far as to replace absolutely all my fluids, thinking on of them got contaminated.

[rwizinsky]

I just got my red dyes, I had no problems with any of the other colors I've messed with , Black, gold, green aen, purple, and others but I couldn't get the red dyes to color the parts well. I did heat the tanks with the new heaters that are set to 110 (I think I'd have to check) while I never heated the other tanks, just left the parts in longer. It seemed to work well but I thought that heating the dyes as the instructions said would decrease dying time. I mixed all the dyes the same, perhaps the dyes were heated up too much and sealed the parts before the dye could penetrate. The 1st time I tried the red dyes I had about 6 parts that I anodized I thought only 5 had anodized and perhaps one came lose but I didn't check ohm check it. The last part I had tried to dye red, perhaps It did anodize correctly and just wouldn't take the dye.

[mcaswell]

I've checked with our dye supplier and here are his recommendations.


1. The fact that you can get all other colors to work has no relevence to red.

2. The dye pH MUST be between 5 & 6

3. Do NOT use LT Sealer. Use the regular sealer.

4. Maintain the sealer at a rolling boil

5. Make sure the nickel acetate powder is at 1 oz per gal di water.


If the sealer is murky = pH is too high Must be 5.5-6


If these things are not adhered to, RED dyes will bleed out.

[rwizinsky]

The problem I was having is it's not taking the dyes at all. It's still the aluminum color after I leave it in even for an hour. That's why I thought the anodize had failed. I didn't get to the sealing part.
Russ

[M_D]

I was wondering what is used to adjust the ph of the dye bath? Acid to lower it presumably, if so, what kind? What should be used to raise the ph? Any suggestions would be appreciated.

I have found red to be one of the most difficult also, although I have had good success also. I received some Caswell red dye recently, and so far can barely get it to tint the parts, although I have not spent much time with it trying various ways to make it work. I anodized a piece of .032" 5000 series sheet as a control sample, which I later cut up into small strips to dye various colors, so I could rule out a totally bad anodize job. It took blue and yellow very well, but the red was just a light tint.

I am enclosing a small picture of some of the parts I have recently done. The part on the upper-left is not anodized, the blue one on the upper-right is etched, and the rest of them are anodized without etching or bright dipping.

The link is to an enlarged version, be forewarned it is large at 330 or kb.
http://www.dotymi.com/cp/anodizing/Anodizing_sample.jpg