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Aperture Blade Material & Coating
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PostPosted: Sun Sep 10, 2023 12:56 am    Post subject: Aperture Blade Material & Coating Reply with quote
Anybody know what aperture blades are made from and what coating is typically applied to them?

From the research I have done the aperture blades can be made from spring steel, aluminum, or plastic.

Spring steel can be blued. What other coating can be applied?
What would aluminum be coated with?
I assume that plastic would not be coated, but you know what they say about assuming. It can make an ASS out of U and ME.


PostPosted: Sun Sep 10, 2023 8:27 am    Post subject: Reply with quote
+1

I am also interested to know.

The aperture blades I have worked with (Minolta lenses mostly) were all magnetic, I have no experience of aluminium or plastic aperture blades.

Minolta's early generation aperture blades were bright shiny, then they became a dull light grey, and later a darker dull grey.

From the wear I have seen it is definitely not paint, but seems to be the result of some kind of chemical treatment process. I would also like to know what the most common process is.

Maybe it could be something along the lines of black oxide conversion?:

Quote:

3) Black oxide conversion

Black oxide conversion is a type of plating process but deserves its own section due to its critical relationship with blackened steel. The process is more similar to anodising than galvanising in that the part’s dimensions do not change. Black oxide conversion involves taking a metal part (typically steel) and immersing it in an alkaline steel blackening solution. The result is a durable coating that will resist colour fading and will not chip, peel, or flake. This makes black oxide conversion an excellent metal blackening process for precision parts that need some corrosion resistance but need to maintain their original dimensions.

quoted from:
https://ludwickprecision.co.uk/what-is-blackened-steel/


PostPosted: Sun Sep 10, 2023 5:36 pm    Post subject: Reply with quote
I think the earlier blades were primarily blued spring steel and those are probably the black shiny blades that you see. Later on you can see that the coating changed but to what process or coating is what I am trying to figure out. It has to be a coating of some sort and pretty sure chances of it being a paint is close to zero.

I have seen plastic blades in later lenses in a service video where acetone affected them negatively. I have not seen aluminum. I have only read about it and am unsure of the accuracy.


PostPosted: Mon Sep 11, 2023 4:34 am    Post subject: Reply with quote
@RokkorDoctor

Do you know is using methanol as a cleaning solution would be harmful to the coating on aperture blades?
Specifically, Eclipse cleaning solution, which to my understanding is pure methanol.


PostPosted: Mon Sep 11, 2023 4:34 am    Post subject: Reply with quote
@RokkorDoctor

Do you know is using methanol as a cleaning solution would be harmful to the coating on aperture blades?
Specifically, Eclipse cleaning solution, which to my understanding is pure methanol.


PostPosted: Mon Sep 11, 2023 9:40 am    Post subject: Reply with quote
cbass wrote:
@RokkorDoctor

Do you know is using methanol as a cleaning solution would be harmful to the coating on aperture blades?
Specifically, Eclipse cleaning solution, which to my understanding is pure methanol.


I'm not sure about methanol.

On the Minolta blackened aperture blades I have used 99% strength Isopropyl alcohol (iso-propanol) as well as 99.9% acetone, and both didn't do any harm at all.

But methanol doesn't behave the same as isopropyl alcohol, as some paints and plastics will be happy to demonstrate...


PostPosted: Tue Sep 12, 2023 4:35 am    Post subject: Reply with quote
RokkorDoctor wrote:

I'm not sure about methanol.

On the Minolta blackened aperture blades I have used 99% strength Isopropyl alcohol (iso-propanol) as well as 99.9% acetone, and both didn't do any harm at all.

But methanol doesn't behave the same as isopropyl alcohol, as some paints and plastics will be happy to demonstrate...


It sounds like the best thing to do is to skip the methanol as it is pretty corrosive and can be corrosive to carbon steel as well as several other materials. I think at this point I am going to throw my eclipse cleaner into the trash. That is essentially pure methanol and they say it is safe for all optics. However, their claims of residue free I have not found to be accurate. It leaves a residue. Also, at some point Sony was saying to not clean their sensors with methanol with the concern being corrosion. On their own website it says with frequent or aggressive cleaning you can wear the coating from the optics.

The acetone may have worked for you, but it looks like it can be risky and damage certain coatings and aperture materials.

https://www.youtube.com/watch?v=mAYE9nocEg0

Sounds like 99% Isopropyl alcohol or naphtha/lighter fluid is the safest choice.


PostPosted: Tue Sep 12, 2023 8:08 am    Post subject: Reply with quote
cbass wrote:
RokkorDoctor wrote:

I'm not sure about methanol.

On the Minolta blackened aperture blades I have used 99% strength Isopropyl alcohol (iso-propanol) as well as 99.9% acetone, and both didn't do any harm at all.

But methanol doesn't behave the same as isopropyl alcohol, as some paints and plastics will be happy to demonstrate...


It sounds like the best thing to do is to skip the methanol as it is pretty corrosive and can be corrosive to carbon steel as well as several other materials. I think at this point I am going to throw my eclipse cleaner into the trash. That is essentially pure methanol and they say it is safe for all optics. However, their claims of residue free I have not found to be accurate. It leaves a residue. Also, at some point Sony was saying to not clean their sensors with methanol with the concern being corrosion. On their own website it says with frequent or aggressive cleaning you can wear the coating from the optics.

The acetone may have worked for you, but it looks like it can be risky and damage certain coatings and aperture materials.

https://www.youtube.com/watch?v=mAYE9nocEg0

Sounds like 99% Isopropyl alcohol or naphtha/lighter fluid is the safest choice.


I was talking about metal aperture blades only!!

Never clean plastic aperture blades with acetone.

Also, unless extremely heavily soiled, I don't dip aperture blades in a cleaning solvent as shown in the video. I apply the solvent to a Q-tip, and then gently wipe down the aperture blade. (I check first that the Q-tip itself can tolerate the solvent, Q-tip distributors regularly change their supplier, even branded ones so you never are 100% sure the new batch of Q-tip will behave just like the previous one).

With the Minolta metal aperture blades, I have not experienced any problems using acetone.

On the rare occasion that I cannot disassemble the aperture assembly for cleaning the individual blades, I dunk the whole assembly in 99% isopropyl alcohol and gently operate the mechanism a few times. Then let it dry thoroughly. In that situation I would definitely not be using acetone due to the risk of excessive exposure to the acetone vapours.
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