To read the blog post "5 Anodizing Defects That Happen in the Handling and Pretreatment Steps" please click here.
5 Anodizing Defects That Happen in the Handling and Pretreatment Steps
To read the blog post "5 Anodizing Defects That Happen in the Handling and Pretreatment Steps" please click here.
8 things you should ask your anodizer about
In my 25 years as a consultant in the anodizing industry, I realized that about 70 % of my consulting clients were not anodizers but the people who had to “deal with” anodizers. Perhaps you have had also frustrating experience ordering anodized parts and not receive what you wanted?
You might think that your anodizer was just not good at their job. Or that anodizers will always try to keep their costs as low as possible and thereby sacrificing the quality of your aluminum product. But that does not do the problem justice. In my experience, the main reason for errors and frustrations is ineffective communication. Yip, just like in any relationship, the relation to your anodizer will improve tremendously by learning how to communicate better.
8 important things to agree on with your anodizer
To make your next phone call with your anodizer much more successful, here is a checklist with all the aspects of the anodizing process you should talk about.
- Agree on the properties and quality of the anodizing results.
- Choose the right alloy to achieve the properties you want.
- Identify the microstructure of your different aluminum parts as this will affect the surface look.
- Agree on handling and racking of the aluminum parts as part of the preparation.
- Decide together on the right pretreatments for the specific parts of your aluminum product.
- Set specifications for the anodizing process as these parameters affect the properties.
- Choose the most environmentally friendly sealing
- Agree on quality control tests that fit the properties of your anodized product.
This checklist is a good start to improve the communication with your anodizer and to receive the correct anodized parts. If you would like step up your game even more and become more confident in asking the right questions, join my new live online training: “Working with your anodizing supplier.”

The course consists of four workshops, each treating an independent subject. You can also attend single workshop days. This interactive live online event is held on Zoom in 4 x 2,5 hours sessions. We will record the presentation and make them available to you after the workshop. The dates of our next courses are:
WORKSHOP SERIES IN APRIL: 7, 14, 21, and 28 April 2021 (03.00 - 5.30 PM CEST)
WORKSHOP SERIES IN MAY: 5, 12, 19, and 26 May 2021 (03.00 - 5.30 PM CEST)
Looking forward to seeing you at AnodizingSchool!
Sunny regards,
Anne Deacon Juhl
P.S. If you would like to learn some anodizing basics, have a look at this blog post in which I give an easy to understand introduction.
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How to Define the Hardness of Hard Coat Anodizing
To read the blog post "How to Define the Hardness of Hard Coat Anodizing" please click here.
Anodizing Aluminum: What it is and Why I love it
We are moving our blog! Anodizing World will still be available, but new posts will be published on aluconsult.com from now on.
To read the blog post "Anodizing Aluminum: What it is and Why I love it" please click here.
Join the Free Webinar about Hard Anodizing
The first event will be a FREE webinar about Hard Anodizing!
The webinar will be a guide to Hard Anodizing, also called Hard Coat including the following topics:
- Intro to Hard Anodizing, also called Hard Coat
- The history of Hard Anodizing
- How to create a Hard Coat
- Properties of a Hard Anodized surface
- How to specify a Hard Anodized layer
- What defects and other problems arising from a Hard Coated Surface
- Some Key takeaways and Q&A
Get 3 amazing benefits!
Influence of temperature on Voltage response when Anodizing
A question from a customer:
We have investigated the influence of the electrolyte temperature in our anodizing tank - Anodizing at a low and a warm temperature, current controlled and in our standard anodizing electrolyte.
The voltage at the higher temperature runs with a lower value than the voltage with the lower temperature and at the same time the voltage stays constant for the duration of the anodizing process.
At the lower temperature the voltage keeps rising until we turn of the power.
Do you have an explanation of why the voltage at the higher temperature stays constant, although the layer thickness is identical with both temperatures (with identical current settings and anodising time)?
Answer:
Higher temperature in the anodizing electrolyte leads to higher conductivity, which means lower voltage for same current and time.
So your Vhigh temp is lower than your Vlow temp
Then
Ohms law gives you V = R x I
Vhigh temp = Rhigh temp x I
I =
same for the two temperatures
The
total resistance of the electrical circuit consists of several resistances:
High
temp:
Rhigh temp = Relec, high temp + Rthickness,
high temp + …..
Low
temp:
Rlow temp = Relec, low temp + Rthickness,
high temp + …..
Lower temperature gives lower conductivity, so Relec,
low temp ˃
Relec, high temp
which is the reason for a higher Vlow temp
Higher temperature of the electrolyte will lead to faster chemical attack of the formed aluminum oxide changing the structure of the formed oxide and the resistance Rthickness, high temp
This will lead to an equilibrium thickness, where formation rate of oxide = dissolution rate of oxide leading to a constant voltage.
Lower temperature of the electrolyte will lead to a higher V0, low temp than V0, high temp for same current I.
The coating weight of the oxide layer is higher when formed at lower temperature - more compact and by this Rthickness, low temp will be higher than Rthickness, high temp.
This is the reason for a continues increase in Vlow temp during the process time but eventually you should see a steady voltage here too.
If you are curious and want to know more about temperature, voltage and other parameters when anodizing in sulfuric acid you should sign up for the first and only online anodizing course!