Aluminum oxidation with Sinar metal frame

Greeting to all,

 

I have recently traded my trusty Deardorff 810 for a Sinar 810P, trust me, there

is madness behind my thinking. Anyway, on the Sinar ground glass holder, there

are many white spots, almost like fungus and feels powdery/chalky when I touched

it. I am guessing it's metal oxidation and if so, what is the cure for it and

how to prevent it from further degradation.

 

I really should have taken a picture of it before I clean them off, but it did

look a lot worst and it's wide spread through out the interior frame and inside

the crests.

 

Thanks for any helpful responses in advance

I lived on the Oregon Coast for some time and had this problem with my enlarging equipment. I'm quite sure mine was from salt water oxidation. My cameras were always in Halliburton cases and never suffered the same problem, thank goodness.

I have the same problem on the frames of the 5x7 inch bellows (normal and bag) of my Sinar Norma. It didn't matter so far, because I only used the 4x5 and 8x10 inch equipment.

 

But this could change - so I would be eager too to know how to clean and treat these frames properly.

Hi Michael, you are indeed fortunate then. My curiosity about my camera's situation is how they might have formed. I am thinking because it's happening from underneath the paint so that means the paint is not offering any protection to the metal. Second, the camera is in the middle of the continent so salty air is not an issue and neither was it out in snow and slush so where is the contaminants coming from. The second concern is how I can prevent it from further developing???? I can't keep it in some vacuumed space for ever right:)

Hi Felix,

 

I don't think it will be an immediate threat the functionality of the camera nor does the cosmetic condition bothers me, but if this is anything like the bicycle fork which I was using in the snow and slush, and it promptly crumpled away like dry turds in a matter of two winters, I would like to know how I can stop if not at least delay the process.

If I had this problem, and it bugged me enough to deal with it, here's what I would do:

 

Sand the entire aluminum part (or all aluminum parts) lightly to remove paint. Once I was down to the aluminum, I would "etch" it with what they (do or did) call 'Metal Prep.' Afterwards I would follow with a good black aluminum paint.

 

The alternative, though I'm not sure of the price (could be very high) would be to have the parts powder coated.

 

I'm no expert on the matter (disclaimer). Hope something here helps!

Thanks for the suggestion Jeff, and oh yes it's bugging me a lot. I was praying that it does not come down to having it completely sanded, re treated and painted. That would be a job and a half given that in fact it's not flat and one piece like a lens board. But if it's the only way of being sure, winter is here...sigh.

The best way (i.e., the way it's done in aviation and aerospace) to deal with local aluminum oxidation is to mechanically remove (sanding, etc.) all the corrosion you can. Clean the corroded area with Alumiprep per the instructions (using gloves of course), treat the now-clean area with Alodine to chemically convert it to a good paint base, prime with a zinc chromate or zinc oxide primer, followed by the top coat of your choice. Nothing else works even half as well. A good auto paint store should have Alumiprep and Alodine, or you can order them from a homebuilder's supply like Aircraft Spruce. This process is a bit of a pain, so you'll have to decide if the benefits are worth it to you.

Having observed a good bit of old aircraft preservation at a local aviation museum, I can second that suggestion.

Thanks John and Frank,

 

Should I do the entire frame or the areas being affected, the reason I am asking is that as I was cleaning off the chalk like powder off the spots, I notice there seems to be a layer brownish substance, approaching the color and texture of the powdery stuff on the surface just under the black paint, so I am wondering if the whole frame is under siege..

The way I figure, it's not that much more effort to treat the whole frame once and be done with it. The problem will probably rear its ugly head somewhere else probably sooner than later if you don't and you're back to square one.

Yes Frank, I figure the same, but the thought sanding/treating of those thread like crests inside the frame(also sports oxidized spots) makes me shiver. Well there's another project add to the to-do list over winter.

 

Thanks all for some very informative responses, happy holidays and happy shooting

The best preservative is to have the Aluminum anodised, sort of a plating process where the surface structure is changed to a stable form of aluminum. Nothing else is as good.

Hi Ronald,

 

Can one do this in the garage, or has to be done at some specialty shop. If the cost of this re-conditioning project goes beyond, what, $200? at which point, it might be easier just shop for another one, right gangs?

Ronald is correct, an anodized surface is THE best way to protect aluminum (in particular, a hard-coat anodize, preferably with a nickel-acetate sealer). This is an involved process that makes lots of nasty waste, and even if you wanted to, I'm not sure you could do it at home. The problem is that the anodizing process isn't amenable to doing one part (at least not cheaply), and shops charge for the batch with a minimum cost ($100 at the last place I used -- Ft. Wayne Anodizing -- 5 years ago). If you did 20 frames or just one, the cost would be largely the same. Another issue is that, for the best job, the anodizer needs to know the alloy to select the proper chemistry and schedule. Not an issue if you're Keith Canham and make your camera from scratch, but if you have an unidentifiable alloy the anodizer will have to make a best guess and the results may be less than optimum. Wrought alloys like 3003 and 6061 anodize beautifully, cast alloys can anodize okay but sometimes unevenly, and high strength aerospace alloys containing copper like 2024 won't anodize at all. This is not to dissuade you from anodizing, just be aware that there are some issues.

2024 can be anodized, its just that one needs a better controlled process. If one has a jackleg anodizer with crap, ie fluorides and clorides in their tanks, improper voltages, then yes 2024 cannot be anodized by the amateur processor. 2024 was the old 24S before ww2, it came out in 1933. 25S/2025 came out during WW1, the war to end all wars. Duraluminum goes back to 1908 in Germany by Wilm for making airships. Alcoa in the USA didnt really ramp up in high tech aluminums until the german patents were used post ww1. Germany had aluminum subs in ww1.

I think this is getting to be way out of my league:-) and ability to take advantage of these informations, hopefully they can be of some use to someone else, someone who is a lot more ambitious and capable.

The answer on anodizing was mostly for the sake of completeness. Its's great if you're making a lot of parts from scratch, but in a situation like this I feel it's unworkable and most likely unnecessary. If it were me, I would sand and scrape off the corrosion, clean it with Alumiprep to clean off all the oxidation, spray it with a can of zinc oxide primer, and then a black topcoat. I've made camera housings for salt water immersion, and then I do the whole hardcoat anodize/zinc chromate primer/epoxy topcoat, but that is blatant overkill for your situation.

Hi John,

 

I think if it's the entire camera frame is under siege as such, I may have to resort to the ultimate measure, specially if I am located or must shoot under that kind of aluminum unfriendly environment. As is, the camera will be used almost strictly in house and no where near salty moisture so I doubt it will be necessary to go that far for something's net worth is not all that high. Thanks again for the very detail curing procedure on the immediate frame ailment though. It's great to have such a forum where there are so many very knowledgeable people around willing to help.

At the summer house I had some camera gear go under salt water, some just get splasted, some that just that got a trace of salt with Katrina. Just one single drop of salt can corrode up a aluminum barrel lens so one cannot focus. Vapor getting to the lenses diaphram is a disaster; the petals/blades get stuck together. <BR><BR>Be carefull with small screws, many cannot be removed even after 1 year of soaking and several dunks in an ultrasonic cleaner. A lens that works often will not if not exercised, and if the fstop is forced the petals/bladed shear at the pivots. <BR><BR>Salt seems to have the damndist ways of adhering to aluminum. Many smaller items that I could take apart were washed clean, scrubbed with a toothbrush, and went thru many ultrasonic baths. Then once the part dries the damn white crud still is seen at many sites on the item. With time one can remove the salt. If you paint the item then it will blister up. if there is still salt on the surface. The salt often gets into the craters of corrosion sites and is stubborn to remove. <BR><BR>Where there are dissimilar metals and salt, one often gets a galvanic cell and more corrosion. High strength materials such as springs corrode like mad too. Ancient LTM Nikkors that are solid brass are quite robust with salt exposure, along with solid Brass Wild tilting levels too. <BR><BR>With some steel items I have used the one part product called Rustbullet, a one part greyish paint that has great affinity to steel, rusted steel, concrete, aluminum, your skin or glasses too. Aluminum items I found a day or two after Katrina that were just wiped off with fresh water have little corrosion. Then there is the Rollieflex TLR I found in the rubble in a zip loc bag, all filled with salt water. The frame is mostly gone, and total basket case!<Br><Br>the choice of paint used should be considered, if painting an aluminum item for salt robustness too.

Wow, I am speechless at hearing your horror stories, Kelly. I have been very fortunate with gears that I almost begin to endowed a false illusion that photo-gears are almost indestructible, other than by deliberate acts of destruction or by accidents that is, but by nature. Wow.

 

Something to think about if there is ever a chance to relocate to any where near the ocean.

 

Come to think of it, the painter I bought the camera from did reside by the water of the great lakes region, I wonder if that maybe the cause of the corrosion. But those are fresh water lakes though....???

I would second (or third) the alodine, it can be gotten from wick's aircraft in smaller bottles, as well as alumiprep. Alodine is a conversion process, it converts the aluminum to a chemically inert variant, e.g. it won't corrode. fairly easy to use, basically wipe on (or dip) wait several mins. and rinse. I have aircraft parts that are over 30 years old still looking like brand new with nothing but alodine on them.

 

erie

Yes, I think from all the valuable informations given above, the alodine and alumiprep is the most practical solution to my situation. At the moment, this oxidation is isolated on the ground frame only, do I need anything more than the small bottles of Alondine and Alumiprep from wick's aircraft as Erie suggested or the assumed the bigger bottles from auto shops.

I would get the Alodine and Alumiprep locally if possible. They come in quart and gallon containers. Because they contain phosphoric acid and the like, they are considered hazardous cargo and usually have a rather high hazmat fee added if they need to be shipped.