Corrosion of anodized aluminum yo-yos


Has anyone noticed, specifically collectors, that anodized yo-yos you’ve had for a year or more develop a subtle corrosion of sorts… intermittent tiny black dots on the surface area of the yo-yo…

Is there any proven method for “polishing” yo-yos that will not in any way damage the yo-yo?

I’m a drummer and I feel like this is a similar question as what cymbal polish/ cleaning method should I use if I want to reduce the chances of removing the logos when cleaning cymbals…


Oh my gosh yes! I was just going to open a topic on this but you said it better than I could!

It’s a difficult thing to take a picture of, but here’s a OD Mantis, not that old, with what may look like dirt on the surface …

… but trust me it is not! Wiping and buffing has no effect on this “dirt”, it’s something underneath the anodization, perhaps?

Anyone else seen this? The Mantis isn’t even that old, it’s from March 2017!


This article may be helpful. I dont have access to the whole thing, but it looks to be relevant.

I did find someone bullet point the conclusions though:

III. Conclusions

● The impedance spectra for the samples that were anodized in the R&D tank mixed acid were very stable during 14 days exposure.

● The impedance spectra for the type III samples suggest that oxide layers are more complex than those for the other samples. The impedance spectra did not change significantly during the 14 days exposure time which suggests that these anodized surfaces were very corrosion resistant.

● The impedance spectra for the production tank samples were very stable for an exposure time of 365 days showing that these surfaces had very high corrosion resistance.

● The very high and stable values of the pore resistance Rpo for all three processes indicate that the newly developed anodizing and sealing processes were very effective.

Therefore im guessing that either the anodized layer was either too thin, or not properly sealed. There is probably not much else you can do to the yoyo to prevent this, but maybe someone in the field can answer the reason why their yoyos have not stood the test of time?


Unfortunately this can happen. While anodizing protects the metal, the surface can still oxidize especially in environments of high humidity. This occurs especially with 7075 yoyos, as the anodizing is often not as thick because of the difficulty in anodizing the metal, and the metal is more prone to oxidizing anyway. One thing you can do to prevent this is coating the yoyo in a thin layer of Renaissance wax, it’s used to preserve metals in museums.


I took some closer pics in daylight. Still really hard to get good pics of, but this might capture it a tad better with more light.

Thanks for the advice above, I’m gonna send a link to this to the one drop guys and see what they say. Definitely a bummer, but looks unfixable without fully removing ano to my eye.


Im actually curious of they would warranty something like that. It shouldnt look like that unless you dropped it into a pool of acid. Their site says nothing of warranty from what I can see, so who knows?


This actually makes some sense. Anecdotally, my supernova (my first 7075 yoyo) has some of these black dots on it. Granted it’s been after 8 or 9 years of pretty consistent play, but I dont think any of my other yoyos have that. I’m not in a place with a lot of humidity either


Not really looking for warranty, just want to hear from the experts on what causes it, how common it is, can all yo-yos 10-20-30 years old expect to start seeing this, etc etc

(Justin ) #9

I hope it’s not common!!


Honestly you seem like a nice guy, but this is a defect level amount of corrosion imo. I wonder if anyone with a similar era yoyo to yours has this issue?


I don’t really care, I’ll just send it to Gruntbull to have it re-anodized if I want.


Some answers from One Drop directly:

Since the issue is under the anodizing, it’s not one that occurs over time. That yoyo was like that as soon as the anodizing was sealed. We had a number of Mantis that came back like that and we sold them as b-grade (NQP). We don’t mark them in anyway, but this did happen with the Mantis. It’s a rare issue, but of course we would never sell them as a-grades.

Since you bought it used and we sold them as NQP I’m not able to warranty it [aside: I didn’t ask for warranty repair, I was only asking for info]. I think it will continue to just be a visual issue and won’t change or get any worse. I would highly highly recommend you don’t strip it and get it re-anodized. This has a high chance of causing the yoyo to become very vibey and also it may not actually get rid of the problem.

I can’t say for sure if [re-anodizing] would fix it or not. Likely the anodizer would have to do a deep etch to through that corrosion, and that would alter the bearing post enough to make the yoyo very vibey. As a general rule, stripping and re-anodizing doesn’t work that well. Introduces vibe and also the the colors tend to look less bright.