Stripping chrome work back to brass - Info

L

Laika

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This isn’t really a ‘how to’ on stripping chrome back to brass, its more like some notes, what I picked up off the net and my own experiences on the topic.

Before you get stuck in make sure you can do the job safely or don’t do it all, I don’t want to scare anyone off but the acid used is a bit nasty if you splash it about. I worked with the stuff for 10yrs and had no problems but basic safety equipment is a must … Safety Glasses, Rubber gloves and a clear work area. A bucket of water handy for flushing is a good idea as well. Also read and re-read the safety warning on the acid container.

Now hopefully now I’ve got my ‘get out of jail free card’ so read on :)

Certain types of chrome can be stripped with acid. I heard about it on 'beststuff Russian forums' when I was toying with stripping and painting a FED. I had a background working with acid as a cleaner for brass and copper parts in the automotive radiator industry (10yrs+) and my FED was cheap so I figured I had nothing to lose. The acid is ‘hydrochloric’ that you can pick up at your local hardware store (often used for pH adjusting swimming pools, cleaning, etching etc.). Once you strip the parts down and give them a very good clean and make sure you remove all the paint from the engravings (if the acid cant get at the chrome it will produce an uneven finish or worse) your ready to go, add enough of the acid to plastic dish (old takeaway container in my case) to cover the plates and place them in. The chrome should start to turn grey and bubbles will form quickly (like a dissolvable aspirin). Every few minutes I would carefully lift out the covers to see how they are coming along and lightly rub an area with a cheap paintbrush if it wasn’t dissolving like the rest. After about ten minutes brass started to show on the edges where the chrome was the thinnest, after 15-20min I had bare brass covers with a slightly etched surface (great for painting). Wash the covers in water and then soap/water and your ready for the next step .. painting or polishing etc.

Notes: Not all the chrome will strip back to bare brass very well. I’ve found the old model FED2’s work great. I tried it on the late dual logo FED2 and the chrome did come off but left a shiny under plating the acid wouldn’t touch (looked like nickel?). Extended time in the acid is not an option as some part may have exposed brass and the acid will eat at it destroying the cover in places but leaving some parts looking untouched. Time wise if it take much more than 30min with fresh acid something is not right and it time to clean up and resort to wet and dry sandpaper. I’d think an hour or two would just about dissolve the cover into something resembling a thin piece of coral.

Safety again: I shouldn’t have to say it but be careful working with acid!! Rubber gloves (A new pair of dishwashing type are ok) and safety glasses are a must. I put a few plastic cable ties thru the hole in the covers to make handling safe and easy. Work in a well ventilated area (outside preferably) and have a hose or at least a bucket of water handy should you spill any of the acid, it will etch brickwork and concrete quickly.

The photo’s are of my FED2 before and after the acid strip followed by a few coats of automotive gloss black in aerosol can and a touch of car wax. The black J8 was bought to finish it off. Aside from the lens I thought it was a nice makeover for about the cost of a home delivered pizza :D
 
You put it so easy that is tempting. I have a Zorki 4 that may experiment a change of colour.
The car wax is for pulling more polished look of the can paint?

Anyhow, your posts are always very usefull and clear.
Thanks.

Pablo
 
Has anyone tried 'reverse electroplating' instead of using acid? I have heard this works well and is comparatively safe (you can use vinegar as an electrolyte) but I haven't tried it myself as I don't have a chrome camera with which I want to experiment!
 
Nice notes! A few extra comments...this form of hydrochloric acid is commonly sold as muriatic acid, and it is fine for stripping chrome. You can use it in a 50/50 mix with water, and the chrome plating should disappear in just a few minutes. Once finished, neutralize with ordinary baking soda...pour this slowly into the acid/water mix until it does not bubble any more. Then you can pour it on the ground safely. Never, ever allow muriatic acid to be poured into an aluminum container. The fumes from this reaction will injure you, and the acid will eat through aluminum extremely quickly. Use plastic or glass only.

About your early FED...if what looked like chrome dissolved all the way down to brass, it wasn't chrome to begin with. I have long suspected rhodium or some other white platable metal was used on these early cameras. Chrome is plated in a three stage process...copper first, nickel second and a very thin layer of chromium last. You can not buy the chemical needed to dissolve nickel without a permit. And, there is a good reason for that.

However, you can dissolve the chrome and wet sand the nickel. Sanded nickel is paintable. Paint won't stick to chrome, though. Good luck.

Jon
 
JLW: I remember an old Modern (Maybe Pop) Photo where they stripped the chrome from a Contax II using reverse electroplating. They used a transformer for an electric train set. I will look for it at home, 1973'ish. They then primed it and painted it black, baked the top plate in an oven. I think a toaster oven would work nicely. I have a spare top plate for the Retina IIIS. Wouldn't a Black IIIS look cool...
 
Any low voltage direct current souce will work for electro or reverseelectroplating. A charged car battery or better a deepcycle battery will work. There was a fad in the USA shortly after WWII to copperplate baby shoes after coating them with a conductive liquid. Many dc power supplies were sold for this purpose. It is possible to run across these in junk stores, flea markets or garage sales etc.
 
I'm working from memory, but I think you'll need a fairly tough electrolyte if you're planning on reverse plating three metals. I'm thinking about something like battery acid. You can use a very mild electrolyte when plating...even as mild as water...but I think you'll do better at dissolving metal back into the electrolyte if you have a pretty high amp power source and a pretty hot electrolyte. Positive pole to the part, negative to a really good quality (non-magnetic) piece of stainless steel should get you started. I wouldn't leave the part itself in there too long, either.
Jon
 
do you have to remove the nickel and copper from engravings before repainting? how do you get it out?
 
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