At least a couple times a month, customers ask us: “Why are there no white aluminum jump rings?” The simple answer is that it’s not possible.

It seems like it should be possible because coloring aluminum is done by dye, and there are white dyes. However, these dyes cannot be used in anodized aluminum. When Jen and I visited our anodizer, he walked us through the process, and explained why this is so.

First, let’s look at what anodizing does to the surface of jump rings. The electricity in the anodizing process makes the metal porous, thereby preparing it to receive dye. Below are two images zooming in on the surface of the anodized metal.

To be more specific, anodizing creates an oxide layer that has roughly one million microscopic pores on the surface of one square inch of aluminum. If you’d like to get your nerd on with more technical information about this process, SubsTech has lots of great articles (open-source!) on their website. The image below, from their page on anodizing, shows how the color is added to “fill the holes” in the surface of anodized aluminum.

Now that you know a little more about the technical side of anodizing, let’s get back to our original question. It’s important to understand that not all dye molecules are created equal, and some colors are bigger than others. Blue molecules have no problem filling in the holes.

Red molecules are bigger than the blue ones, but they still fit, no problem.

Unfortunately, when we get to white molecules, they are so large that they do not fit into the holes created by the anodizing process! There’s no way to squeeze a white molecule into the pore!

Another way to look at the size comparison of molecules:
Imagine a pore the size of a basketball net.
A gold dye molecule is the size of a golf ball.
Blue dye is about the size of a tennis ball.
Red and black dyes are about the size of a baseball.
Scientists haven’t been able to get white dye molecules smaller than beach ball size, which is too large to fit.

And that, fellow maillers, is why there is no white anodized aluminum.

Now some of you may think that you’ve seen white anodized aluminum. It’s true that our anodizer can get a color fairly close to white, by etching the aluminum and then sealing the surface just as would be done after dyeing colored anodized aluminum. But the color most definitely is not a pure white, and can vary from a muted grey to a dirty off-white. If you see someone selling “white” aluminum, they have most likely used this acid-etched process.

Blue, red and white molecule illustrations by Artie Keefe and Erik Watson. (more…)

anodized aluminum · Anodized Aluminum 101 · anodizing · chemistry · dye · molecules · white aluminum · white anodized aluminum

Several months ago, Blue Buddha Inventory Coordinator Jen and myself visited our aluminum anodizer. Because so many of you have expressed interest in finding out more about the anodizing process, we want to share some of the photos from our site visit.

You may know that Blue Buddha has never done aluminum anodizing in-house, nor do we plan to. Why? Well, unlike anodizing titanium and niobium, which can be done purely by electricity, anodizing aluminum is a multi-step process involving lots of icky chemicals and dyes. If we took this on, we’d have to get all sorts of special waste disposal permits from the city. In short, it is a whole other business model that I do not want to get involved with! I’ll leave that to the experts. Our anodizer is very conscientious about waste and hazardous materials disposals. Innovators in their industry, they’ve found ways to turn waste products into useable materials for other industries, and they’ve received much recognition for their environmental efforts.

Here are some highlights of the anodizing process. There are several steps that we’ve omitted — let’s face it, photos of dipping rings in acid solutions and rinse water (which happens a few times throughout the process) get old quickly. So, here are some of the more interesting parts of the process.

Early in the process, our jump rings are put into a tiny basket and compressed. They need to be very densely packed in order to allow the flow of electricity to pass through all the jump rings. This flow of electricity–the anodizing process–makes the surface of the jump rings porous (you’ll find out more about this in an upcoming post). After the rings have been anodized, they are transferred to a larger basket in order to add the color.

The rings are now brought over to whatever color bath is appropriate. In this case, turquoise rings are being made. The rings are dipped quickly into the bath, and then pulled out. Note the steam in the second photo — the dye is HOT!

The amount of time the rings need to stay in the dye is astounding – a mere 5-20 seconds gets the job done for most colors. In fact, the process is so sensitive that leaving the rings in an extra second or two will cause them to be a shade or two darker than they should be. (Hence our first post in this series: Color variation is just a fact of life.) Here, the anodizer compares the color of the rings against our “target color” sample board to see if the rings need to stay in the dye for another second.

After the rings are finished being dyed, the color is sealed in, effectively closing the pores on the surface of the metal. (See the next article in our series for more about the porous surface.) There are sometimes a few rings that have not taken the color. This means they didn’t receive electricity during the first part of the process. Our anodizer is working on adapting their color-monitoring machine for our jump rings. This means that as the rings pass through the machine, if they do not meet the target color within a certain tolerance, the machine will flick them off the assembly line. Quality control of the 21st century!

When it’s all said and done, the rings await being packed and shipped to our shop.

And finally, this is the image that made me laugh the most. Here at B3, we have jump rings all over our floors. (I know, you’d never believe it, but it’s true! *cough*) And apparently, at the anodizing factory, they have drips on their floor. What can I say, it’s the little things in life that make me smile.

anodized aluminum · Anodized Aluminum 101 · anodizing factory · anodizing jump rings

Welcome to the first article in a series of three that we’re calling “Anodized Aluminum 101“.  Ever wonder what causes color variation?  Want to know what the anodizing process looks like?  Not sure why there are no white anodized aluminum rings?  Stay tuned to find answers to all these questions…and more.

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We make it our priority to give you the most consistent products we possibly can.  We do this because as artists ourselves, we know it’s important.  You have a vision and you need certain materials to make it into a reality.  We not only get it – we’re obsessed with it.

In the beginning of 2010, we started on a journey to create our own anodized aluminum rings and we set out on that journey with our persnickety ways in tow.  Everything worth doing is worth doing right and to us, right means bright, even, shiny color and as much consistency within each batch (and from batch to batch) as possible.  While we take the time to quality control every batch of rings before we package and sell them to customers, we certainly don’t want the process to be too time-consuming to be cost effective or to produce too much waste.  Basically, consistency is key.

We are now making 100% of our own anodized aluminum rings and still looking for ways to improve them.  The fact is however, that color variation (to some extent) will just be a fact of life.

There will always be some level of variation within each batch and variation is even more likely from batch to batch (and from size to size) as they are all dyed separately.  To make these variations play nicely in our world of perfection, we quality control our anodized aluminum rings – ditching broken or malformed rings altogether, and demoting off-colored rings to our sale packs.  In the few cases where there is still a great deal of variation (which happens most often in rings with a small surface area such as our D20 and F20 rings), we toss in an extra 10-20% to give you more rings to choose from if super-consistency is important to your project.  We are also happy to answer questions about the color of our current batches before you purchase them.  In the rare event that we have a color that is very different from our normal stock, we indicate that on our website with a note and/or by changing the name of the color altogether.  We do what we would want someone to do for us – give us the best product they can and communicate when it’s vastly different from what we’ve gotten used to.

Throughout this journey, we have learned a number of things not least of which is that anodizing is a fickle process.  (A fickle process associated with chainmaille?  Never. *wink*)  Fickle process or not, however, we are committed to producing the most consistent product we can (what can we say – we like a challenge!)  To read more about this quest for consistency and to learn more about the anodizing process, check out the next article in this series coming tomorrow - Visit to an aluminum anodizing factory.

anodized aluminum · Anodized Aluminum 101 · colored jump rings · quality control