Anodizing: Getting "Stuck" at Purple

[Sharperthansticks]

I've been playing around with anodizing for some weeks. The thing is, my results are fairly inconsistent. At different times, different voltages are required to achieve the blue right past purple at the upper end of the voltage range, right around 80V. Sometimes 81V will give me a perfect, deep blue, and sometimes I need to give a voltage closer to 84V. Lately, more and more, I seem to be getting "stuck" at purple, and my results just give me a washed out purple. It's like the metal doesn't want to budge past purple, and if I crank up the voltage, I get some washed out mess.

Any ideas?

 

[115Italian]

Check if there is a drain from somewhere. Bad connection? Damaged wiring?

 

[tiguy7]

Here is a high voltage bright apple green.

 

[Sharperthansticks]

View attachment 1153541 Here is a high voltage bright apple green.

How does that help my situation?

 

[tiguy7]

I have my son in law do my Titanium anodize work. So I am not as familiar with the settings as he is. My guess is that your wattage (amps X volts) is too low. I called him and he said the 80+ volts usually achieves the bright green, but the amperage runs about 5.

 

[Sharperthansticks]

I have my son in law do my Titanium anodize work. So I am not as familiar with the settings as he is. My guess is that your wattage (amps X volts) is too low. I called him and he said the 80+ volts usually achieves the bright green, but the amperage runs about 5.

There's more than a little to discuss here:

• Unless your son-in-law and I are using substantially different means to anodize, you normally set the voltage and only the voltage. At least that's what you do on a power supply that costs $135 or less. If he has a machine that allows you to control both the voltage and amperage, this is significantly different technology. Why? Because the load -- the water, electrolyte, metal that is being anodized, surface properties of the metal, and on and on -- are what determine the impedance, and hence the amperage for a given a given voltage. How could you fix your amperage [I corrected "wattage"], after all, if your impedance was really high; you'd need an enormous amount of power (wattage).
• Different surface preparations will take substantially different colors at the same voltage. A shiny surface will not look anything like a bead blasted surface at the higher voltages, so it's really proper to speak in terms of the surface preparation, too. Those scales you posted look to have a satin finish. Still, 80V seems quite low to achieve that green, which usually comes around 95V or so. For typical colors at each 1V point, see these pictures that Holt Bladeworks provides.
• The amerage running "about 5" is a bit vague. 5 amps, or 5 milliamps? I don't think my $135 DC power supply can output 5A, but when a color is just about set, .05A or .005A is a reasonable value shown on the display for the current.

 

[WValtakis]

How old is your electrolyte? Sometimes things get wonky and a fresh batch of distilled water and TSP-not combined with a fresh etch gets it right again for me. I've also had pieces that refused to hit that high range green, but I was unsure of the alloy.

~Chip

 

[Sharperthansticks]

How old is your electrolyte? Sometimes things get wonky and a fresh batch of distilled water and TSP-not combined with a fresh etch gets it right again for me. I've also had pieces that refused to hit that high range green, but I was unsure of the alloy.

~Chip

Yeah, I thought of that, and have tried several times with fresh electrolyte, but I do reuse my bath a lot, or I'd need distilled water to be delivered to my home. I use baking soda. Is TSP better?

Edit: By the way, I'm not trying to get to green; I'm trying to get to the blue right after purple (which happens at around 81V for a shiny surface).

 

[tiguy7]

There's more than a little to discuss here:

• Unless your son-in-law and I are using substantially different means to anodize, you normally set the voltage and only the voltage. At least that's what you do on a power supply that costs $135 or less. If he has a machine that allows you to control both the voltage and amperage, this is significantly different technology. Why? Because the load -- the water, electrolyte, metal that is being anodized, surface properties of the metal, and on and on -- are what determine the impedance, and hence the amperage for a given a given voltage. How could you fix your amperage [I corrected "wattage"], after all, if your impedance was really high; you'd need an enormous amount of power (wattage).
• Different surface preparations will take substantially different colors at the same voltage. A shiny surface will not look anything like a bead blasted surface at the higher voltages, so it's really proper to speak in terms of the surface preparation, too. Those scales you posted look to have a satin finish. Still, 80V seems quite low to achieve that green, which usually comes around 95V or so. For typical colors at each 1V point, see these pictures that Holt Bladeworks provides.
• The amerage running "about 5" is a bit vague. 5 amps, or 5 milliamps? I don't think my $135 DC power supply can output 5A, but when a color is just about set, .05A or .005A is a reasonable value shown on the display for the current.

He might have been talking about milliamps, and I think the voltage was 85. He comes up with all sorts of colors. I can pick his brain for you, but I will have to pay closer attention and take notes.

 

[Stang Bladeworks]

I've been playing around with anodizing for some weeks. The thing is, my results are fairly inconsistent. At different times, different voltages are required to achieve the blue right past purple at the upper end of the voltage range, right around 80V. Sometimes 81V will give me a perfect, deep blue, and sometimes I need to give a voltage closer to 84V. Lately, more and more, I seem to be getting "stuck" at purple, and my results just give me a washed out purple. It's like the metal doesn't want to budge past purple, and if I crank up the voltage, I get some washed out mess.

Any ideas?

I had a similar problem. Are you using multi etch and are you getting it hot? It needs to be 170f if my memory is correct. It seems to do nothing below this temp. Once you etch your ti in the acid for about ten seconds you will get a wider range of more vibrant colors. Without it you get fewer colors and poor finishes. The surface finish effects color as well. Blasted gives a more matte color and polished is brighter. Ferrum forge has a great youtube video about this. Also watch the grimsmo ano tutorial video. This should get you up and running.

 

[eKretz]

You can't control both voltage and amperage. A power supply can do constant voltage or constant amperage, never both. The reason is that it has to constantly adjust one to keep the other stable.

Do you have any sulfuric acid? That's what I use (diluted with water) for anodizing Ti. However, I don't think the electrolyte solution is your problem. I would tend to think you have a bad connection or perhaps a broken wire somewhere.

 

[Sharperthansticks]

I've been waiting to write you guys back to give some updates and responses to your comments.

How old is your electrolyte? Sometimes things get wonky and a fresh batch of distilled water and TSP-not combined with a fresh etch gets it right again for me. I've also had pieces that refused to hit that high range green, but I was unsure of the alloy.

~Chip

Sometimes I reuse my ano batch too many times and I get a white residue that gunks up everything, but I've been having poor results even with new ano batches.

I had a similar problem. Are you using multi etch and are you getting it hot? It needs to be 170f if my memory is correct. It seems to do nothing below this temp. Once you etch your ti in the acid for about ten seconds you will get a wider range of more vibrant colors. Without it you get fewer colors and poor finishes. The surface finish effects color as well. Blasted gives a more matte color and polished is brighter. Ferrum forge has a great youtube video about this. Also watch the grimsmo ano tutorial video. This should get you up and running.

If you read one of my previous response, you'll see that I talk about different surface colors resulting from different finishes. You have a point about the MultiEtch, though. Sometimes I skip it because I figure that the handle is fresh from being Flitzed, so it hasn't developed the oxide later, yet. (I thought I saw others that skipped the Multi-Etch sometimes.) I went back to MultiEtching, and it's true that it's easier to get those popping colors.

*********************

Now for the updates:

So now I Multi-Etch and am trying to use fresher ano baths, and I've made the additional change of going for the low voltage (20V) blue instead of the high voltage (80V) blue. I was able to get some beautiful, deep blues, but now one of my old problems has come back: fading ano. I think I'm beginning to realize why manufacturers only give us anodized titanium handles if the handles are stonewashed or blasted -- but never polished. The ano just fades.

Notice the front of this Falcon Wing, where the blue ano almost immediately faded from the top of the wing. (Windex or alcohol cannot get it back.)

As for the back of the knife, it never really looks blue, because of fingerprints.

 

[Stang Bladeworks]

I've been waiting to write you guys back to give some updates and responses to your comments.



Sometimes I reuse my ano batch too many times and I get a white residue that gunks up everything, but I've been having poor results even with new ano batches.



If you read one of my previous response, you'll see that I talk about different surface colors resulting from different finishes. You have a point about the MultiEtch, though. Sometimes I skip it because I figure that the handle is fresh from being Flitzed, so it hasn't developed the oxide later, yet. (I thought I saw others that skipped the Multi-Etch sometimes.) I went back to MultiEtching, and it's true that it's easier to get those popping colors.

*********************

Now for the updates:

So now I Multi-Etch and am trying to use fresher ano baths, and I've made the additional change of going for the low voltage (20V) blue instead of the high voltage (80V) blue. I was able to get some beautiful, deep blues, but now one of my old problems has come back: fading ano. I think I'm beginning to realize why manufacturers only give us anodized titanium handles if the handles are stonewashed or blasted -- but never polished. The ano just fades.

Notice the front of this Falcon Wing, where the blue ano almost immediately faded from the top of the wing. (Windex or alcohol cannot get it back.)

As for the back of the knife, it never really looks blue, because of fingerprints.

I found that prepping the surface with alcohol helps but its true that getting a perfectly uniform color is difficult. I find this problem is more exaggerated the higher your voltage is set.

 

[Sharperthansticks]

I found that prepping the surface with alcohol helps but its true that getting a perfectly uniform color is difficult. I find this problem is more exaggerated the higher your voltage is set.

You misunderstand me. I get a uniform color in the ano bath. Shortly after handling the piece, the ano fades in "high traffic" areas. (Neither Windex nor alcohol restores it.)