8mm Forum: Gray powder in old projector

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Topic: Gray powder in old projector

Thor Simpson
Junior
Posts: 9
From: Surrey UK
Registered: Jan 2013

posted January 05, 2013 12:28 PM

I've bought and old Eumig 610D (on eBay) and it arrived beautifully packed. But there is a light gray powder over many interior surfaces. It does not vacume off but a power toothbrush moves it. Before I risk breathing in or speading too much of it around, can anyone suggest what it is and what caused it?

Thanks

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted January 05, 2013 03:52 PM

It looks like aluminum oxide.

Does a magnet stick to the parts affected by it?

--------------------
All I ask is a wide screen and a projector to light her by...

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Graham Ritchie
Film God

Posts: 4001
From: New Zealand
Registered: Feb 2006

posted January 05, 2013 04:39 PM

I think you will need to try to remove as much of the surface corrosion as possible and treat "whats left" of the remaining material, if its possible. It looks really bad and could have been caused by salt in the air, dampness, anything, or the material was simply of poor quality with little or no resistance to corrosion to begin with.

If you do give it a go, as well as treating the remaining material, I think you will have to seal it with some sort of anti-corrosive paint as well, that should keep the air "oxygen" away from it.

best of luck

Graham.

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Pasquale DAlessio
Film God

Posts: 3523
From: Bristol,RI, USA
Registered: May 2010

posted January 05, 2013 05:05 PM

Graham is right. Use a vaccum cleaner with the brush attachment. Then seal it with automotive zinc oxcide primer. Then your good to go. [Wink]

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Thor Simpson
Junior
Posts: 9
From: Surrey UK
Registered: Jan 2013

posted January 06, 2013 11:53 AM

Thank you all. Magnet test - its non magnetic.

Have removed one part and left it overnight in coke and its cleaned up quite well.

Need the full service manual before I risk disassembling the rest.

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Steve Klare
Film Guy

Posts: 7016
From: Long Island, NY, USA
Registered: Jun 2003

posted January 06, 2013 12:58 PM

Thor, it looks like you've struck "aluminium"!

The oxide is not dangerous, and Graham is right: it's likely the result of the environment the projector was kept in.

In a lot of cases I'd say just ignore it, but little flecks can cause major mayhem inside a movie projector.

Maybe after you clean the effected parts a spray of acrylic clear will prevent it's return and preserve a normal appearance where it's visible.

--------------------
All I ask is a wide screen and a projector to light her by...

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

posted January 06, 2013 02:06 PM

Any exposed Aluminum alloy (Al) will naturally oxidize to aluminum oxide (Al2O3). Humidity and moisture will really accelerate this process. There are two solutions that manufacturers can use to prevent this. The first, which is very inepensive, is to dip the parts in a Zinc Chromate bath. This process is called 'Irridite' or zinc chromate conversion coating, and puts a nice yellow protective coating on the surface of the aluminum, which also makes it ideal for painting. This is required procedure for use of aluminum on military equipment, and its very suprising that Eumig did not use it, as it is really cheap. The second process is electrical anodizing, which puts a very hard resistant coating on the Aluminum , and you can get just about any beautiful color you want - but it is expensive.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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Thor Simpson
Junior
Posts: 9
From: Surrey UK
Registered: Jan 2013

posted January 06, 2013 02:17 PM

Steve, I think its concern about the stray particles when running a film that have me making the effort to clean it all.

Graham, Paul, Thanks. Its an eBay purchase and as I want to "reconfigure" it I didn't ask about condition , just did it run.
I do not know when the 610D was in production but I suspect this one has just languished in some attic for many years.

Paul Have you tried making a "Zinc Chromate bath" or are we in laboratory stuff her?

Regards Thor

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Lee Mannering
Film God

Posts: 3216
From: The Projection Box
Registered: Nov 2006

posted January 06, 2013 02:31 PM

1/ Take it outside and with a soft brush it will come off.
2/ Put some WD40 on a cloth and rub it over the alloy.
3/ It will then be good as new.
4/ Enjoy your Eumig!

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Paul Adsett
Film God

Posts: 5003
From: USA
Registered: Jun 2003

posted January 06, 2013 07:02 PM

Thor, I believe the zinc chromate conversion process bath uses some chromic acid, which is really nasty stuff. One of those things that only the professional metal finishing companies should be messing with. EPA, OSHA, etc is involved.
I would say that if you are going to strip this projector right down to the bare aluminum chassis, that a plating house would do a far better job of cleaning off the old oxide than you can possibly achieve. Once they have it stripped, it would cost you very little to have the chassis subjected to the zinc chromate process, as any good plating house will be doing this process on a daily basis and will have the tank all set to go.

--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj

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Thor Simpson
Junior
Posts: 9
From: Surrey UK
Registered: Jan 2013

posted January 07, 2013 12:18 PM

Lee , I will give that a try, but its so extensive I'm leaning towards Paul's suggestion and looking round for a company that can do it.

Thanks both.

Thor

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