Getting started in anodizing: Mesh?

March 18, 2008

Here is a typical question that I get asked:

I would like your advice: Besides the plastic container, what else do I need to anodize titanium grade 23 or grade 5. I called Reactive Metals to buy the machine for $206 , they told me to buy a mesh but I do not know what or where to buy it. I am a little scared of getting hurt if I do not know how it really works.

Any help will be really appreciated.


The question seems to be, what is needed to get started. Peter has already bought an anodizer, a 0-150vdc voltage supply.

The “mesh” might be one of three things.

  • A large-area cathode (negative pole immersed contact) could be a mesh of titanium or even stainless steel. I use a coil of wire for this, but a plate of metal does fine. Ideally, you want to have a non-conductive porous material ( maybe a plastic mesh) between the cathode and the work piece, in case of contact. Rubber non-skid shelf liner mesh/screen is cheap and good for this.
  • A mesh basket made of niobium wire makes a good anode connection for loose parts. A titanium wire basket will work, too. Just not quite as reliable at higher voltages.
    Note: I haven’t tried this myself. I use a homemade titanium clip and the niobium clips that ReactiveMetals sells.
  • A plastic mesh basket such as a salvaged automotive windshield washer fluid filter can also be used on the anode side by running a niobium or titanium wire into the basket full of little parts.
    Note: I haven’t tried this myself, but have heard of it being used by others.

One can easily weave your own basket from titanium or niobium wire.

One important final note: If you are afraid of getting hurt, please do some more reading about electricity and safety precautions. Wear rubber gloves, and always double check where all the live contacts are when you are working. Read my old anodizing page over until you understand everything in it. It may not be complete, so do ask questions to help me fill it out.

How to tell if a piece of metal is really titanium.

March 17, 2008

Let’s assume that you found or are given a metal piece, strip, sheet, rod or wire that you hope is titanium. Titanium can be many colors, and it might have any number of coatings. I’ve received titanium covered with rust, that transferred from a piece of steel in a wet shed. I have some titanium now that has a tenacious ceramic-like coating that conducts electricity, and is a bear to grind off. I had to get it all off of a piece to do and anodizer test.

How do you tell if it really is titanium?

First: Titanium is non-magnetic. If a magnet sticks, then no. I always carry a neodymium magnet for scrap yards and estate sales.

Are there any grade markings on it? If so, there are many that might mean titanium in its many grades and alloys. Most alloys can be anodized. I usually Google the numbers to see what variation of what grade I find in scrap yards. Many different specifications exist for chemically/commercially pure titanium, depending on sub percentage trace elements (mostly oxygen) and what certifications it has received (mil-spec, medical, etc).

File or sand off an edge to be sure you are looking at the bare metal. It should be a shiny dark silver. Compare it to a piece of (freshly scratched) aluminum; it should be much darker. If the fresh metal is a different color, then, no.

Does it anodize to color? If you can get to a bare piece of metal, just apply a moist cathode (paper towel) to the positive-attached metal. 9v should do to get a slight tan tinge. 18v (2 9v batteries) will take you to dark violet.
Note:Niobium and tantalum will color the same way. But they are heavier and softer and more expensive.

If you touch it to a typical rotary hard grinder, the sparks should be bright blue-white.

If you have a way to measure its specific gravity (ratio of weight to volume, water is 1.0 g/cc) then you have another good test.
Titanium and its alloys range closely around 4.5 g/cc.
Aluminum is noticeably lighter (2.7 g/cc),
Iron and steel are distinctly heavier (7.8 g/cc).
Tantalum is much heavier (16 g/cc).
Niobium is about the same as brass (8.5
Copper, bronze, and brass are up to 9 g/cc, but you’ve already eliminated them by color.

If you have samples of steel and aluminum in the same size range, the relative weight is easy to check.

Shavings of titanium (from drilling or milling) burn much as magnesium strip does. Shield your eyes if you resort to this test. btw: Magnesium is much lighter in weight (1.7 g/cc).