I need to strip chrome from aluminum?

[RedRiver]

Hi all...It's my first time here. Be patient, I'm destined to screw up somehow...lol

Anyway, I've been doing some type II aluminum anodizing for quite some time now with terrific results. I started with small and slowly moved my way up to a larger scale setup (40 gal tanks). I do a fair number of paintball markers and have not yet come across a hitch - until today. I've done oodles of markers and when it came to do my own, I hit a stump! To present, I have always stripped the original anodic layer off with Caswell's anodizing & chrome stripper. Thus far this has been fruitfull but today when I when to strip what I believe to be chrome of my trigger (aluminum base metal), I couldn't get it to work (I've never tried stripping chrome before).

I should also mention that this chrome has a tinge of brownish to it and fingerprints are often left in a sort of bluish hue. What I think is chrome may be something else but I really believe it is chrome (perhaps nickle) plated.

What I did is as follows :

Using the Caswell anodizing & chrome stripper at room temperature (71F), I connected the negative lead of my 12 battery charger to a steel cathode and the positive lead to the chrome plated trigger. I submerged the cathode and the trigger into the solution and let sit for what seemed like forever. Running the battery charger at 12v and 2 amps the cathode and trigger both bubbled immesley, however, the chrome did not appear to come off the trigger. I should note that the steel cathode did turn black.

My questions to you are :

1. Doesn't chrome have nickle underneath?

2. Is it possible that the chrome has been stripped and I am left with the nickle at this point?

3. Once the chrome is gone, how do you remove the nickle? I need to strip this baby down right to the bare aluminum.

Thanks for any help you can send my way...I'm really stuck on this one!

[RedRiver]

Re: I need to strip chrome from aluminum?

From what I have been reading...I would do the following :

Using the Caswell anodizing & chrome stripper at room temperature, connect the hot side of a battery charger to the part being stripped and the negative lead to a stainless steel cathode (?). Submerge both parts into the solution for 15-20 minutes (?). At this point the chrome should be gone (how do you tell?) leaving behind a nickle plate. To remove the nickle, use a solution of 50% water and 50% nitric acid. Hang the part in the solution at room temperature for 15-20 minutes. This should remove the nickle and copper underneath the nickle if it is present.

Does this seem correct. I've been reading and reading and reading and this is what I have come up with thus far. How do you know when the chrome is stripped off and the nickle is left? Don't the two look similar in appearance? It appears that there are many different ways to strip chrome and it really depends on what the base metal is.

Thanks again!
- Dan

[sswee]

Re: I need to strip chrome from aluminum?

I anodize, haven't got to plating yet. When you strip chrome in the method you just described, the chrome usually flakes off. Sometimes you will have to pull the part and rinse it to check the progress. The chrome and nickle are similar in color but you should be able to tell the difference. The chrome is shinier than the nickle. I haven't gotten any nitric acid yet for the nickle and copper. I have been blasting it off so far. Depends on how well it was put on as to how hard it is to get off this way. Hope this helps some.
SS

[RedRiver]

Re: I need to strip chrome from aluminum?

Well....I have oodles of Nitric Acid. I'll let you know my outcome tomorrow around noon CST.

Question...You say the chrome will "flake" off using the method in which I have described above...So I assume that the stripping of the chrome should be very noticeable during the process and not "invisble" or difficult to see? Am I correct in the assumption that stainless steel is the correct cathode for the chrome strip? 316 stainless to be precise...Also, is the Caswell anodizing and chrome stripper used at room temperature for chrome stripping? I use it at room temperature to strip anodizing...Curious.

Thanks again!
- Dan

P.S. For the record today I tried an aluminum cathode and a mild steel one. I just read something about the cathode being stainless steel. I'm hoping that this is my "cure-all" and am going to be trying it tomorrow.

[sswee]

Re: I need to strip chrome from aluminum?

Where is the best place or type of place to get the nitric acid? I'm just outside of Austin TX , so I figured someone there would carry it but haven't found anyone yet. I guess I'm looking in the wrong places.

The chrome I've stripped so far has been very noticeable. I've tried mild steel and stainless, didn't notice a big difference between the two.

I use the Caswell anodizing and chrome stripper at room temp. for stripping anodize and chrome.
SS

[RedRiver]

Re: I need to strip chrome from aluminum?

Actually, I purchased my Nitric Acid in a bulk order I placed with my local chemistry and lab dealer here in the city (Canada). I use the nitric acid in a 50% solution with H20 as a quick and easy anodizing sealing test.

I would suggest looking up your local chemical supplier. I think that is the only place you'll find it - though I may be wrong. It is the only place where I could find it!

Cheers!
- Dan

[RedRiver]

Re: I need to strip chrome from aluminum?

OK...For the record, this is how I easily and effectively stripped my chrome paintball parts.

Materials Required

1. Caswell Anodize & Chrome Stripper
2. 12 volt manual battery charger
3. Stainless steel cathode (I used a 3 x 5 piece of 1/8 thick 316 s/s)
4. 2 x 5 gal pail (or something large enough to submerge the part in)
5. Nitric Acid
6. Stainless steel pot (large enough to submerge part)
7. Tap water
8. SAFETY GEAR (goggles or shield, rubber gloves, apron, ect...)

Proceedure Utilized

1. Mix the Caswell Anodize & Chrome stripper in one of the 5 gal pails (room temp).
2. Fill the other 5 gal pail with water (for rinsing).
3. Connect the negative lead of the battery charger to the stainless steel cathode and suspend the cathode in the stripping solution.
4. Connect the the positive side of the battery charger to the chrome plated part which is to be stripped and suspend the part in the stripper solution (with the battery charger off).
5. Making sure there is no contact between the cathode and the part to be stripped, turn the battery charger on (I used the 2 amps setting to strip a paintball marker trigger).
6. Bubbles will form in the solution as the chrome is being stripped. Pull the part out from time to time and rinse it in the rinse pail in order to check the progress. (I found it difficult to know when the chrome was completely off so I can not provide an exact duration but I would estimate about 10 minutes).
7. Once the chrome is stripped, the nickle which is left behind must be stripped. Mix a 50% Nitric Acid and water solution into the stainless steel pot. CAUTION : Always mix acid into water, never water into acid. Mix slowly.
8. After rinsing the stripped part in the rinse pail, submerge it into the Nitric Acid solution. It should turn colors (almost black) as the nickle and copper (which is under the nickle) is being stripped off. CAUTION : Do not breathe fumes and strip in a well ventilated area. Dispose of waste accordingly.
9. The nickle and copper are removed when the color fades from black, bronze to dull grey (this is the aluminum etching - I think). Rinse the part and re-polish or treat as desired.

I don't think I left anything out...Good luck and BE SAFE! Please dispose of waste accordingly!!

[UFpball7]

Re: I need to strip chrome from aluminum?

does it happen to be a CP roller trigger? if it is than it is nickel not chrome.

[RedRiver]

Re: I need to strip chrome from aluminum?

Steps 7-9 will remove the nickle...And no, it wasn't a CP trigger. Thanks for the input though...Cheers!

[fly]

Re: I need to strip chrome from aluminum?

RedRiver,

One thing you want to remember is not to leave the alum. part in the nitric for a long period of time, you want to keep a eye on the part so that the nitric does not eat into the alum. cause it will over time..it takes a while but it will eat at the alum.
The grey color is a etching affect.
The chrome plate is very thin so it will not flake off, its the nickle that flakes off. Strip half the part at a time to see what it looks like when the chrome is removed to get a better idea of how long it takes to strip the chrome, it only takes a few seconds.
The nickle thats under the chrome will have to be activated after stripping if you want to plate over the old nickle, just dip in pickle #3 for 30 sec. and rinse and then plate over the nickle.

[RedRiver]

Re: I need to strip chrome from aluminum?

FLY :

The grey color is a etching affect.

RedRiver :

9. The nickle and copper are removed when the color fades from black, bronze to dull grey (this is the aluminum etching - I think). Rinse the part and re-polish or treat as desired.

Fly...Thanks for your input but perhaps you should go back and read my post. To start with, my last post concerning the process wasn't a question, it was a detailed and informative layout of how I easily and successfully stripped my chrome plated aluminum parts. It was so easy and so effective that I intend to utilize this process each and everytime I need to strip chrome plate from aluminum. Secondly, I never once made mention of replating the aluminum parts...Infact, I was stripping the chrome so I could then go ahead and anodize them...For this, obviously the nickle would need to be removed and the copper underneath that.

I appreciate you trying to help but next time perhaps you should follow along with the thread before clicking the "Submit Reply" button.

Cheers!!

[fly]

Re: I need to strip chrome from aluminum?

Ok be that way then!!!!!!!!!!! You will not have to worry about my input on another one of your post thats for sure....

[RedRiver]

Re: I need to strip chrome from aluminum?

Hmmm...I really didn't think I was being rude...I appologize if you've been offended Fly. That's the problem with forums and cummunication via text, its so impersonal. The reader is left to determine the emotion within the text and it is so often interpreted incorrectly. I wasn't trying to slap you on the wrist Fly...Infact, I'm pretty sure that I mentioned that I appreciate your input...

Cheers bud!

[fly]

Re: I need to strip chrome from aluminum?

Yeah I guess I took it the wrong way, and I am working night shift so please disreguard my comment. If I can help with anything just ask.....

[RedRiver]

Re: I need to strip chrome from aluminum?

Thanks Shane! I'm glad we both better understand eachother now...Cheers!