stripping chrome from bronze hardware

[mark g]

recently I read a few entries of how to strip chrome. Many people described "home brews". As a professional I discourage it. Let a chrome shop do it. Most people dont realize that the chrome layer is usually only .00003-.00008. The hard part is stripping the under layer of nickel which is usually .0005-.0009 thick. If anyone insists on trying it themselves, care must be taken when using any acids or caustics. Mark g

[sdowney717]

i am going to try it myself. And I have enough basic understanding and wisdom to be safe.

I called a certain recommended rechromer, they are backed up several months and besides wanted a lot of money. Plus it would have to be shipped. The lousy message on their machine made me very unlikely to be interested in using their business.

here is a repost of just how its done.


The 'home brew' method works very well - I have been doing some (safe & controlled) experimentation on some 6 inch, chrome plated, bronze cleats and the results are good, infact, very good.

What I did is purchase some '30%' Hydrochloric Acid and diluted 1:4 with water (as per the instructions on the jug - acid into water, never water into acid!!)) in a HDPE container big enough to hold the cleat. Following suggestions/information from a plating company, I then passed 12v (low amperage Battery Charger) through the solution, using an old bronze bolt as the anode and the cleat itself, as the cathode.

Literally, as soon as the current was switched on, the cathode(cleat) began to bubble and the solution turned green, I left it in the solution for a minute, turned off the power and behold, a nice bronze cleat and not a hint of chrome. Unfortunately, I didn't have my camera to record the moment but will try it again tomorrow, on another one and take some before/after shots.

It is essential that the item to be treated is fully submerged otherwise you get a 'tide' mark!

This was all carried out in a well ventilated environment (important as gas is given off when the current is passed through the solution) and all safety precautions were adopted when handling the chemical!! (gloves, respirator, safety glasses etc.) The waste solution has been retained in an appropriate container for correct disposal at the conclusion of the testing.

I am no chemist, so this method is NOT a recommendation to others as to how to remove chrome - I have an electronic engineering background so am used to dealing with circuit etching etc. and just wanted to show that chrome can be removed chemically.

NuS

[Figment]

I had a boxful of hardware stripped by our own Mark G a few years ago. He knows of what he speaks.
I've tried a few "homebrewed" approaches before and since, and none of them give the results of the professional process. Conceptually, it's a simple process, but there appear to be a number of small opportunities to screw up along the way.

[jimmy]

I'm not sure why you started a new thread rather than just replying to the other one, but anyway. Maybe I'm wrong, but I think this forum is largely for people who do the work on their boats themselves. It's great when pros give advice, but it's equally frustrating when they just say you should get a pro to do it and don't really say why. It kind of seems like they are just promoting their business. Many people for various reasons don't have the option of going to pros or it isn't practical. I mentioned in the other thread that the chrome stripping pros in my area charge a fortune so that it is cheaper to buy new parts. What I didn't mention is that they were also very unhelpful on the phone and really didn't seem to want my business.

So what I would have liked to hear from a pro was what is likely to go wrong and how to avoid it or how to decide whether to do it or not, not just that it's too difficult and dangerous, pay me or one of my buddies to do it. If the main problem was dealing with dangerous chemicals you might decide to go ahead and do it if you work in a lab and already have access to all the safety equipment. If the main problem is that you just won't get it as shiny as a pro, you might not care if you are just doing cleats or were going to let the bronze go green or brown anyway.

Anyway, I have worked a lot in a lab. I tried it and it was very easy and cheap. If you have similar skills you may be able to do it too. If you have any doubt either buy new hardware or hand over a bunch of cash to somebody like Mark.

As I mentioned in the other thread, there is a whole forum of people who do this at home where you can get information:
http://forum.caswellplating.com/forumdisplay.php?f=6
Edit/Delete Message

[Andrew Craig-Bennett]

I'm a bit puzzled. The chrome is there to save you from polishing the brass.

My boat was built 70 years ago - and looks earlier than that, being a very traditional English gaff cutter.

All the bronze deck fittings - portholes, skylight rods, even the compass binnacle, were originally chromed!

[jimmy]

The chrome eventually comes off in spots and patches and looks like crap. When this happens you can leave it, rechrome it, or strip it. Some people prefer the patina of weathered bronze to polished bronze, brass, or chrome.

[George Ray]

The waste solution has been retained in an appropriate container for correct disposal at the conclusion of the testing.

Correct Disposal ?? Where other then Denmark can one dispose of such stuff?

I'm not trying to give you hard time or put you on the spot. Way too often I find myself disposing of things in a manner that is not ........ 'ecologically nice' but is only 'convenient'. If there is/are good places to dispose of 'STUFF', I want to know!

http://www.sustainabilityinstitute.org/dhm_archive/index.php?display_article=vn271kommunekemied

[jimmy]

I'm not sure why Mark doesn't want to answer my questions. Basically we have a couple of people who have tried this and said it was easy to do, but dangerous mostly because of the acid involved. One person even gave detailed instructions. Then there's Mark who says it's really hard you should get a shop to do it, but won't say why. I wanted to get a shop to do my hardware, but couldn't get the information I needed to feel comfortable making that choice. If anyone else knowledgeable is willing to share information here are a few questions that somebody else comtemplating this might find useful:

1. What are the dangers or problems of doing it yourself? The danger of working with a very strong acid is an obvious one, are there any others? Do the fumes eventually make you very secretive about the process and easily offended?

2. How can you get the best value from getting a shop to dechrome stuff for you? All of the 3-4 shops I called were very unwilling to give out information and only one grudgingly admitted that it would be cheaper to get a whole bunch of items done at once, but wouldn't tell me much more.

3. How can you estimate how long a shop will take or how much they will charge you? None of the shops I called would give me any guess on how long it might take, yet they were charging $95/hr. It's hard to write somebody a blank cheque at that rate. Does it depend on the state of the chrome, surface area, shape, complexity, size? I had a fynnspray type pump that took me a whole afternoon to take apart and dechrome piece by piece. Obviously a shop would be more efficient, but if they took half the time a new pump would have been cheaper.

4. Can the part be damaged either by yourself or a shop? We've heard that one shop etched away a lot of the surface of one person's parts. Is this common? Can there be underlying damage like leaching the zinc out of brass? How do you avoid this?

5. How do you chose a shop? We've heard that all shops are not the same. What questions do you ask?

6. Are some items better candidates for dechroming than others (at a shop or at home)? Obviously value of the item is one consideration ($, historical, sentimental, etc.), but are there others?

As for George's question about disposal, I think that could be one of the biggest problems with doing it yourself, but I suspect a high school chemistry textbook would help out a lot. I would guess that what you end up with is a solution of copper, nickel, and chromium in hydrochloric acid. Hydrochloric acid neutralized with sodium hydroxide turns into water and sodium cloride (salt). It's the metals in solution that are a problem and that's where the chem text might help. You may be able to precipitate them out, evaporate the solution, or even plate them out onto another piece of metal, I'm not sure. The actual amount of metal involved is tiny and I wouldn't be surprised if it was legal to neutralize the acid and pour it down the drain, however, it would be nice to find a more environmentally friendly solution. For now, I've just kept my solution since I have more parts I may want to do.

[mark g]

I will try to elaborate on a few of your concerns.
First, safety is the first reason to not do stripping at home for most people who are not trained or used to working with corrosive chemicals. Yes it is cheaper to have as much done at once since they will be put into a basket and stripped in a batch. This applies to my shop and for stripping the nickel only. The chrome is stripped differently. The best thing anyone can do in choosing a shop is get a written estimate, not to exceed a certain dollar amount. Also agree on a competion date with a reasonable window. Ask questions on procedure. I always give customers my procedure so they understand the process from old to beautiful is more than "dunking the parts in a magic tank" Understand that time is money. Never ask them to skip steps to save money. I wont do it because the end result will be lousy and my signature is on the job. Most important NEVER go into a shop with an attitude> Attitudes cost money. What I am getting at is if you dictate the procedure and act like you know more about the process than he does you are asking for trouble. We are regular people like anyone else. Be respectful of our knowledge and reputaion and there should never be a problem. If you dont feel comfortable with the shop go elsewhere.
If parts are stripprd carefully no damage should occur other than hidden pits may now show up. Nothing can be done to avoid this. Hope I helped Mark

[jimmy]

Thanks Mark, that sounds like good advice. Sorry for any attitude that may have came accross in my messages. Hopefully most people have access to people like you to do this for them and don't end up in the back yard with a bucket of acid and a battery charger like me (unless they want to of course). It worked out for me, but obviously could go horribly wrong. Thanks again.
J

[sdowney717]

as far as used up acid you can

dilute it with a lot of water and simply dump it in the sewer.
neutralize it with a base and dump it in the sewer.
let it sit in a plastic labeled jug for years and years in your garage and then dump it down the sewer.
kill weeds with it.
clean off your old rusty driveway and rinse it into the street.

I cleaned up a lot of old bronze screws, cast iron, heat exchangers with 30% HCL. You can buy the 30% at the HDepot. It is pool acidifier.

Get it on your hands and it will start stinging and have plenty of fresh hose water to rinse it off.

[KNOCKABOUT]

I have an old girlfriend from Long Island who could take care of this in fifteen minutes, and send you to the stars if you treat her right... ;)

[P.I. Stazzer-Newt]

If parts are stripprd carefully no damage should occur other than hidden pits may now show up. ....

Always assuming that the customer has correctly identified the substrate....

Ever see a chromed mazac casting stripped?

[mark g]

This is very true. It is very important to identify the substrate in order to properely strip a part. Most deck hardware (to the weather) will be bronze or zinc die cast(if chrome plated). Other materials may be stainless steel or alum or other alloys like z mac for instance and probably anodized. The stainless will be either electropolished (bright) or at least passivated to eliminate any free iron from the surface. Anyway a qualified finishing house will be able to figure out what the substrate is. Mark g