Anodizer power supply questions

J

J. MacDonald

Joined
Jun 8, 2000
Messages
3,140
I am looking to learn a little about doing ano work on 6AL4V ti for folder parts. I have an old lab grade variable DC power supply and am wondering if it might be useful for this task.

Basic specs are:

1-7Vdc it's rated at 5 amps

0-25VDC it's rated at 2 amps

0-60VDC it's rated at 1 amp

Will this work or will I be suffering from lack of voltage or current? Will this get me some colors?

What do you guys think?
 
60V will get you through the first set of colors, I believe. There's a second, more pastel set up above that, sort of like a "harmonic", if I can abuse the term. IMO, 1 amp will be enough. Electrolyte concentration and electrode size are big players in the equation. If you're doing one set of Ti liners at a time that oughtta work fine.

That little reactive Metals anodizer is only 1 amp.....
 
Thanks for the feedback Mike. So you think I could get a decent blue or red at 60V 1 amp? I was reading an article in Knives Illustrated that says you can make an ano rig with a mason jar, some sheet ti in the jar dor the anode I think and a piece of ti for the cathode (my terms) in a bath of distilled water and TSP.

Think this will work (please correct terms if I'm off)?

Sorry, can't help with the ham, egg and tater craving.
 
Hook the negative lead to a strip of titanium at least as large as the part you want to anodize. Put that strip in the jar filled with Formula 409 cleaner. Hook the part to a piece of titanium wire and connect the positive lead to it. Make sure nothing but the titanium is submerged! (For instance, steel will rust immediately if not masked off.) Also make sure the part does not come in contact with the piece of titanium connected to the negative lead. Then, turn on the power supply and watch the color appear.

If you're doing folder scales, you should at least be able to get gold, bronze, purple, and blue. Light blue, light green, pink, and mottled colors appear with move voltage - but only if adequate amperage is available.

Red isn't possible on titanium.

See www.reactivemetals.com for more info on the setup.
 
John, ask Mr. Anderson here questions. He's anodized more Ti than I'll ever see in one pile.

Tom, do you mean 409 straight out of the jug, no dilution?

I'll give an unsolicited plug for a fellow maker: consider buying Peter Atwood's anodizing video. That and a couple emails with Peter and Tom helped me most.
 
Thanks for the info guys. I always learn something here. Looks like I'll have to get some 409 tonight and play with some scraps. I have a couple sq. feet of some .040 Ti. I was thinking of cutting a piece large enough to line a large mason jar, then put plastic mesh inside that to keep the workpiece trom shorting against it. Does that sound like it would work. The largest thing I'd probably be doing for a while would be .125 x 1.25" x 4.5". Will I have enough juice to work with something like that? How about the disparity in thickness between the plate and the workpiece?
 
John, anode size ratio to target piece has bearing on the efficacy. This is one of the things I'm still working out. I don't know if it's mass or surface area, but it seems important.
 
Yeah - Peter actually bought his anodizer from me.

You want the surface area of the piece of titanium that stays in the bath to be at least a large as the piece you are anodizing. I covered mine with Nylon webbing to avoid accidental short circuits.

You can use straight Formula 409, or dilute it with distilled water. (I just said straight 409 because it's easy to do for most folks.)

I use a solution of TSP in distilled water - about 1 tablespoon per quart.

I've heard folks say they use other types of electrolyte as well, anything from Windex to Coca-Cola. There are a number of different electrolyte recipes used for anodic painting too, but I use the same TSP/distilled water solution for both types of anodizing.

Since a thin oxide layer starts building up from the moment they are exposed to air, you usually get the best results with titanium pieces that have recently been finished and haven't had the chance to oxidize or get too dirty. (One person told me he actually keeps freshly sanded parts submerged in Windex until he's ready to anodize.)

I'm too clumsy to have a bunch of trays of liquid lying around the shop, so I take a little time and clean all my fingerprints off the parts before storing them in sealed bags or boxes. Then, I simply wipe them off with Windex before dipping them in the tank. Seems to work well.

Let's see if I can get my Voltage/Color Chart to come up here:

DC VOLTS....COLOR ACHIEVED.....NOTES:

10............ LIGHT GOLD
15.............DEEP GOLD
20.............BRONZE
25.............PURPLE
30.............BRIGHT BLUE
35.............SKY BLUE
40.............POWDER BLUE
45.............BLUE-WHITE
50.............GREEN-WHITE
55.............PALE GREEN
60.............PALE YELLOW-GREEN
65.............GREEN-YELLOW
70.............GREEN-GOLD
75.............COPPER
80.............PINK
85.............PINK-PURPLE
90.............BRIGHT PURPLE
95.............BLUE-PURPLE
100...........PURPLE-BLUE
105...........AQUA
110...........GREEN WITH RED MOTTLING.....SOLUTION STARTED TO SIZZLE
115...........GREEN WITH PURPLE MOTTLING.....SOLUTION SIZZLED
120...........BLUE WITH PURPLE MOTTLING.....SOLUTION SIZZLED RAPIDLY
125...........MOTTLED PURPLE, GREEN, AND BLUE.....SOLUTION SIZZLED VIOLENTLY! STARTED TO "BURN" EDGES OF PART!
 
Tom, sorry to pester you with questions but this thread can teach us all who are interested:

have you tried the "etching" of parts before anodizing and does it change the results versus if one has freshly sanded the surface?
 
No problem, I'm glad to offer help whenever I can! ;)

I've been meaning to try some of the etchant sold by Reactive Metals, but haven't had time to do so. I'm sure an etchant would do a better job at preparing the surface than simply wiping it off with some off-the-shelf household cleaner.

A group of fellows and I did another experiment a while back comparing tank anodized titanium parts to those that were heat colored. The heat colored parts stood up to abrasion much better than the tank anodized parts. I need to get my microscope out some day and try to figure out why.
 
That one I can answer.Heat coloring of Ti is much deeper in penetration than the thin film color of anodized Ti. Back in the 70's they used to make Ti pendants and ear rings with heat coloring.
 
I've heard the same observation before about the differences in durability. The question that raises to me then is that it sounds like two different chemistries of coloration?? If anodizing colors come from light diffraction through specific thickness of clear oxide, what causes the color in heat colored Ti if it actually penetrates and isn't a shallow surface film?

I'm confused.... not necessarily a hard thing to do. :confused:
 
Mike:

I'm not positive but, since the color is determined by the thickness of the oxide layer, it might have something to do with "surface contact".

With tank or brush anodizing, the oxides build from the surface in. A good example is if you dip a part with tiny blind holes (divots) in an anodizing bath, the divots won't color because tiny air pockets are created. One could speculate that this happens on a microscopic level, as well.

When heat coloring, all of the moisture is removed from the part and the oxides build from the surface out. That means that all of the minute nooks, crannies, and crevices have the same oxide layer as the outer surfaces of the part.

At least, that's my guess.
 
Sounds quite reasonable to me, Tom. Good explanation. Thank you! :)
 
Awesome info, especially that color chart. Thanks Tom. I wish I'd have seen some of these posts before I went and bout a big jug of 409 last night as I have a brand new box of TSP already on the shelf. Oh, well, at least it has other uses.

For power supplies, do you think a DC controller for a variable speed motor like what one of the guys here used to build a cheap variable speed drive for his grinder would work? I think they get up to at least 90 volts but am not sure if they'd like the load which I'd guess to be almost purely resistive.
 
I've used various lab power supplies for anodizing over the years, but I really can't offer a qualified answer regarding the suitability of other types of DC power supplies for this application. Sorry.
 
John, here's a tip for saving your Ti piece in the jar for another knife.

Wrap a sheet of stainless heat treating foil around the inside of the jar. It works as well as Titanium. Cut a little tab on the edge to hook the ground clip to. I just shove the tab down and close the lid when I'm finished.

Be sure to line the jar with a sheet of rubber shelf lining after placing the stainless foil around the outside (of the inside) :rolleyes:

The rubber sheet will provide insulation in case you accidentally touch the anode to the cathode.

By the way, as far as I know, it's not possible to get a red color by anodizing Ti.

Another tip: Sand blast, then glass bead blast the Ti before anodizing. The satin finish will retain the color much longer.
 
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