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"Finishing Technology Hotline BBS" Postings by Topic

Ed. note: before the internet existed, there was a time when "Sysops" (system operators) ran publics forums via dial-up modems and "BBS" (Bulletin Board System) software. Here is one such discussion from 1994.


Nickel-Chrome Plating



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Msg. #5083 in ** Ask Plater B**
Posted on 04/28/94 at 22:49:32
To: JOEL TOMASETTI From: TED MOONEY - Reply To 'Chrome in Nickel Baths'
Neither. I don't think you will find it possible to dummy chrome out of a nickel bath at any current density, high OR low. There are procedures for using ferrous sulphate, raising the pH, and filtering--and they may work for you. You probably should go into this bath electrically "hot" so the chromium does not dissolve this way.

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Msg. #5085 in ** Ask Plater B**
Posted on 04/29/94 at 19:22:16
To: JOEL TOMASETTI From: BERL STEIN - Reply To 'Chrome in Nickel Baths'
Joel: Whatever advice you get, you'll have to test it yourself to make sure it works, and I can't think of a better and easier way to do it then in a Hull cell. Simply take your contaminated solution, run a standard test for your baseline, say at 1 A for 5 min. Then, treat the solution, say, with hydrogen peroxide, and start dummy plating at a low current density (.5-1 ASF), watch the cathode appearance, then go higher in amperage, etc. After dummying for what you think would be enough (2-4 hours, I once did it for 12), run another Hull cel under standard conditions and see if if helped. Trial and error, but it always works. Good luck, Plater b

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Msg. #5087 in ** Ask Plater B**
Posted on 04/29/94 at 19:43:29
To: BERL STEIN From: TED MOONEY - Reply To 'Chrome in Nickel Baths'
I agree on hull cell testing, Berl. And I'll agree that dummying can remove tramp metals. But it took one of plating's greatest inventions to just get chrome to plate _at_all_, with the sulfate ratio just right. I don't think there's any possibility of plating chrome out from a nickel sulfamate bath.

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Msg. #5089 in ** Ask Plater B**
Posted on 04/30/94 at 20:41:45
To: TED MOONEY From: BERL STEIN - Reply To 'Chrome in Nickel Baths'
It may not be possible to dummy hexavalent chromium out directly, but some combination of oxidation/reduction along with pH manipulation might get it out
- remember, we are not trying to make it plate bright and shiny, or coherent at all, for that matter
- we just want to get rid of it. People who plate Cr on top of Ni must be doing it routinely..., since cross-contamination is almost unavoidable with mass-production techniques. Plater B

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Msg. #5091 in ** Ask Plater B**
Posted on 05/01/94 at 15:15:25
To: BERL STEIN From: TED MOONEY - Reply To 'Chrome in Nickel Baths'
People who plate chrome on top of nickel _are_ routinely removing impurities from the nickel. They are dummying to remove copper and other stuff; but I think they are using ferrous sulphate to precipitate the chrome, and filtering it out.

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Msg. #5096 in ** Ask Plater B**
Posted on 05/01/94 at 23:09:39
To: ALL From: TOM PULLIZZI - chrome in nickel use bisulphite to reduce chrome, then hi pH treat to remove trivalent if the person who is interested would call me at 609-361-2272 I would't mind sharing my reference material with him

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Msg. #5103 in ** Ask Plater B**
Posted on 05/04/94 at 08:11:10
To: BERL STEIN From: STEVE RUDY - Reply To 'Chrome in Nickel Baths'
Generally cross contamination, or chrome backwards into the nickel bath is almost nil in occurence. That's chiefly due to the specific arrangement of process tanks and rinses. But there is one typical source of chrome contamination into the nickel bath. This is poor condition of rack coatings (tears, rips, pinholes, etc...). Chrome solution may not totally drain out as the racks return and some chrome seeps in the nickel bath. Another chance, although remote is the drag in of chrome contaminated electrocleaner. It's got to pass the post cleaner rinse and acid plus post rinse. As Tom mentioned the best purification procedure for hexavalent chrome in nickel is sodium metabisulfite reduction to the trivalent state followed by precipitation as the hydroxide, above pH 5.0. Another older practice was to add a lead salt to precipitate the lead chromate, but the status of lead prohibits this procedure. SFR

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Msg. #5104 in ** Ask Plater B**
Posted on 05/04/94 at 08:23:23
To: TED MOONEY From: STEVE RUDY - Reply To 'Chrome in Nickel Baths'
Yes, quite correct. And what a curious position regarding chromium. It cannot be dummy plated out of a contaminated plating bath. Just as metallic contaminants cannot be dummy plated out of hexavalent chromium plating bath. Berl, if you thing the bath may contain hex chrome, immerse a brass panel in the solution dead for about 30 seconds, then plate. Splotchiness or blistered plate will likely verify the presence of hexavalent chromium. You can also employ the dephenylcarbazide spot test,as a color test confirmation. Another neat test is to reduce pH of a test tube sample of plating solution to 2 with sulfuric acid. Add a few granules of potassium iodide or 10% potassium iodide solution. Next add a few mls of a non polar or weakly polar solvent (methylene chloride, tec...) if hex chrome positive, the bottom layer in test tube (solvent) will be pink to red colored. This is result of hex chrome oxidizing iodide to elemental iodine. It's a sensitive test down to 25 ppm of hex chrome. SFR

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Msg. #5107 in ** Ask Plater B**
Posted on 05/06/94 at 22:17:42
To: STEVE RUDY From: BERL STEIN - Reply To 'Chrome in Nickel Baths'
Looks like I missed a couple of messages 'round here when they appeared- thanks to all who contributed with good advice and experience in this murky business. Plater B

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Msg. #5149 in ** Ask Plater B**
Posted on 05/12/94 at 12:10:29
To: BERL STEIN From: STEVE RUDY - Reply To 'Chrome in Nickel Baths'
No problem, I hope the information helped. SFR

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Msg. #5232 in ** Ask Plater B**
Posted on 05/31/94 at 07:04:33
To: TED MOONEY From: TOM PULLIZZI - Reply To 'Gold color abrasive resistant coatings.'
the gold colored faucets I saw being plated 7-8 years ago were nickel, brass, super duper epoxy lacquer then bake, they were beautiful, I have never seen the tinted lacquer over nickel being done, is that the way the industry has gone?

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Msg. #5234 in ** Ask Plater B**
Posted on 05/31/94 at 09:06:44
To: TOM PULLIZZI From: TED MOONEY - Reply To 'Gold color abrasive resistant coatings.' --is that the way the industry has gone?-- To hear Atotech tell, yes. If you need to lacquer brass anyway, I guess it makes more sense to just tint the lacquer and skip the brass, huh.

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Msg. #5257 in ** Ask Plater B**
Posted on 06/01/94 at 15:16:21
To: TED MOONEY From: TOM PULLIZZI - Reply To 'Gold color abrasive resistant coatings.'
if the appearance is just as good, I don't see why not.

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Msg. #5264 in ** Ask Plater B**
Posted on 06/04/94 at 16:47:51
To: ALL From: TED MOONEY - Chrome-like finish? If someone wanted to get away from using chrome, yet wanted to provide a bright, shiny, chrome-like finish on zinc die-castings, what should they do? The application is plumbing fixtures, so, personally, I'm not so sure that a lacquered finish is a good idea. Now, lacquer _COULD_ be used on top of a sputter coat or vacuum metallizing--after all, lacquer is used on brass. But, whether it's my wife, or my mother, or my mother in law, or the restaurant cleanup crew, they _all_ use scouring powder on chrome fixtures. So is it really prudent to switch to lacquer? On the other hand, sputtering has been used on exterior automotive parts and apparently the public got used to it. Are there any coatings along the line of titanium nitride that are shiny chrome-looking instead of gold-looking? All of us in this industry are going to need an answer to the question of how to eliminate chrome in non-critical situations.

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Msg. #5265 in ** Ask Plater B**
Posted on 06/05/94 at 19:10:31
To: TED MOONEY From: BERL STEIN - Reply To 'Chrome-like finish?' Ted: In the latest P&SF I saw an ad from Enthone on a new chromium substitute
- a Co plating process. They are claiming it to match chrome appearance-wise and be hard enough for many applications. Is that the thing you're looking for :-)? Cheers, Plater B

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Msg. #5266 in ** Ask Plater B**
Posted on 06/05/94 at 20:59:03
To: BERL STEIN From: TED MOONEY - Reply To 'Chrome-like finish?'
Yes, that may be what I'm looking for. Thanks.

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Msg. #5267 in ** Ask Plater B**
Posted on 06/05/94 at 23:40:02
To: TED MOONEY From: TOM PULLIZZI - Reply To 'Chrome-like finish?'
i did see that lacquer over brass years back on fixtures and on vacuum cleaner covers so I guess softscrub won't eat it up too fast.

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Msg. #5268 in ** Ask Plater B**
Posted on 06/06/94 at 07:47:58
To: TED MOONEY From: BERL STEIN - Reply To 'Chrome-like finish?'
Correction! Correction! The ad appeared in the June issue of Products Finishing, on the inside of front cover. It's for the ENLOY Co-300 cobalt alloy. Enthone-OMI. (are they getting free publicity here?) Anyway, I don't remember seeing that ad before. Plater B Msg. #5284 in ** Ask Plater B**
Posted on 06/10/94 at 08:00:28
To: TED MOONEY From: STEVE RUDY - Reply To 'Chrome-like finish?'
For an aesthetic substitute, lacquers, with dyes could be used. However, the service life characteristics of the deposit would not match chromium as a top coat. I'm referring to hardness, scratch resistance, etc... The only option would be to alkaline electroless nickel strike the zinc piece, then follow with a high phosphorus acid electroless nickel.Look for one half to one mil of thickness. Afterward the part could be baked in a slightly reducing atmosphere at 750 deg. F to improve hardness. If the yellow look is preferred, look into suitable yellow dyed lacquers over the electroless nickel. Obviously this all increases the cost to process the part. SFR

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Msg. #5285 in ** Ask Plater B**
Posted on 06/10/94 at 08:02:52
To: TOM PULLIZZI From: STEVE RUDY - Reply To 'Gold color abrasive resistant coatings.'
The tinted lacquers you refer to are now being looked at as an alternative to brass plating. Bright nickel plate, then dip into a yellow lacquer. SFR

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Msg. #5286 in ** Ask Plater B**
Posted on 06/10/94 at 08:08:03
To: TED MOONEY From: STEVE RUDY - Reply To 'Gold color abrasive resistant coatings.'
Ted please refer to reply# 5284. I also mentioned in another reply that brass yellow colored lacquer dips over bright electroplated nickel are being looked at. Obviously, in the humid atmosphere of the Jacuzzi, a chrome deposit would be optimum. But consider electroless nickel, as per#5284. Are you sure the lady in California didn't check out Continental's peanut fares? SFR

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Msg. #5287 in ** Ask Plater B**
Posted on 06/10/94 at 08:10:34
To: BERL STEIN From: STEVE RUDY - Reply To 'Gold color abrasive resistant coatings.'
For abrasion resistance (scouring cleansers, friction etc...) and ability to stand up to humid conditions the brass and lacquer combo won't really cut it. If brass is to be used, I suggest looking into the feasibility of electrolytic lacquers. SFR

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Msg. #5306 in ** Ask Plater B**
Posted on 06/15/94 at 16:17:45
To: ALL From: JERRY GIRA - chrome plating variation Can anyone shed some light on this question? If you reduce the current density in the chrome plating process by 50% do you at the same time reduce the chrome plating thickness by 50%? In other words is there a direct relationship between the factors that determine the plating thickness and the amount of chrome that gets deposited? I'm working on chrome plated aluminum wheels and we are seeing large variations in chrome thickness on a given wheel that seems to be dependent on the shape of the wheel and the use of auxiliary anodes. Any comments will be greatly appreciated.

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Msg. #5307 in ** Ask Plater B**
Posted on 06/15/94 at 16:32:40
To: JERRY GIRA From: TED MOONEY - Reply To 'chrome plating variation'
Faraday's Law says one gram-equivalent-weight of metal will be deposited per Faraday of electricity if the operation occurs at 100 percent efficiency. The efficiency has to do with how much of the electricity goes to actually laying down metal vs. splitting water into hydrogen and oxygen. Many plating operations (acid copper, nickel, etc.) operate at close to 100 percent efficiency, release very little hydrogen and oxygen, and the relationship between electricity used and thickness of deposit is very linear. But all bets are off with chrome! The efficiency is usually only 12 to 15 percent; 85+ percent of the power is wasted in liberating hydrogen and oxygen. Even worse, the efficiency drops dramatically as the ASF drops (which is why thickness distribution is so horrible and auxiliary anodes so critical). My bet is, if you cut the current density in half, the amount of chrome you will deposit is zero or negligibly close.

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Msg. #5310 in ** Ask Plater B**
Posted on 06/16/94 at 23:36:05
To: ALL From: MIKE SICA - Brighteners for Copper Sulphate Are there any good brighteners available for BARREL plating high-leveling coper sulfate?

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Msg. #5311 in ** Ask Plater B**
Posted on 06/17/94 at 07:29:43
To: MIKE SICA From: BERL STEIN - Reply To 'Brighteners for Copper Sulphate'
Mike, I don know if brighteners specifically for barrel applications have ever been developed, but my feeling is that a lot of PC Board brightener systems should work well with barrel plating. One pretty decent two-component system I am familiar with is Chemcut's Cupracid HS. Of course, the company changed hands, but I think the product should still be available from them. If you need more details, give me a call @ (201)785-4630. Plater B

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Msg. #5312 in ** Ask Plater B**
Posted on 06/17/94 at 10:20:53
To: TED MOONEY From: JERRY GIRA - Reply To 'chrome plating variation1'
Thanx for quick response. What I need to know now is are the copper, semi-bright, bright nickel layers affected in the same way? We are trying to write a specification and engineering drawing callout to guarantee a certain performance for chrome plated aluminum wheels. Any suggestions appreciated. p.s. What is "asf"?

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Msg. #5313 in ** Ask Plater B**
Posted on 06/17/94 at 16:40:16
To: JERRY GIRA From: TED MOONEY - Reply To 'chrome plating variation1'
oops, "ASF" is "amps per square foot", a measurement of current density. For practical purposes, I would say the thickness of the copper and duplex nickel layers are directly proportional to the amp-hours per square foot, as per Faraday's Law. You can get a booklet called "Quality Metal Finishing Guide--Decorative Copper-Nickel-Chromium" from the Metal Finishing Suppliers'
Association 708/887-0797. It's either free or a nominal cost like $5. It was written for exactly the purpose you want: to help specifying engineers decide and understand exactly what they want and how to write a spec most likely to do what they envision. Usually your spec will be product based rather than process based, i.e., you'll say you want so many thousandths of semi-bright, rather than saying how long the part should be in the tank. The booklet also introduces the idea of the "STEP" test, the most important test and biggest key to predicting corrosion resistance that our industry has seen in the last several decades.

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Msg. #5322 in ** Ask Plater B**
Posted on 06/22/94 at 10:14:46
To: TED MOONEY From: JERRY GIRA - Reply To 'chrome plating variation11'
thanks Ted. You have helped us avoid a major mistake. I've ordered the booklet you mentioned; it sounds helpful. Now if I can only find a good paint to stick to chrome to protect the backside of the wheel! Any takers out there?

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Msg. #5346 in ** Ask Plater B**
Posted on 06/29/94 at 08:06:32
To: TED MOONEY From: STEVE RUDY - Reply To 'chrome plating variation'
Per your interest to chrome plate the aluminum wheels, lets zero into just this segment of the complex, critical steps involved in to (lost transmission) tal aluminum wheel finishing. As Ted mentioned hexavalent chromium i (lost transmission) s a very inefficient (lost transmission) p(lost transmission) process, exhibiting the poorest d(lost transmission) is distribution of any electrodeposited mey metal. Excuse the interference, I'll try to reply later. SFR

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Msg. #5349 in ** Ask Plater B**
Posted on 07/01/94 at 07:52:56
To: STEVE RUDY From: STEVE RUDY - Reply To 'chrome plating variation'
Chrome plating the aluminum wheels does involve a complex operation that needs to be carefully adhered to. Each process tank exhibits a key operation in the success of total aluminum wheel finishing. If you wish to focus on chrome plating, I offer these processing tips, assuming wheels being processed cover the range of consumer products on current motor vehicles. After nickel plating, more than likely a steel auxiliary anode will have to be positioned to cover the front of the wheel. Interestingly, most aluminum wheels are designed with baffles and holes, in an aesthetic design, having that racy or class look. Needless to say this point makes aluminum wheels difficult to plate. This necessary design is to cool the brakes, by maximizing air flow. Hexavalent chromium, exhibiting the poorest distribution of any metal electroplated, becomes a finishing challenge on the aluminum wheels. Hence, the need for auxiliary anodes. Once the anode and wheel have been hooked up live, immerse the wheel in the chrome plating bath. I would suggest wiring the rectifier to use perhaps four separate power switches. First, use switch #1, which permits the flow of full desired current, after approx. 20 seconds, shut off #1 thereby running on three open switches, or 75% total power, in a proportional time sequence repeat this procedure, down to the last switch. Best chrome deposit throw and coverage is obtained in this way. Simple but important. It would be prudent to consider processing wheels in this way using a hand line approach. s

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Msg. #5350 in ** Ask Plater B**
Posted on 07/01/94 at 08:20:39
To: TED MOONEY From: STEVE RUDY - Reply To 'chrome plating variation1'
Please also note my reply to Ted mooney regarding the chrome plating of aluminum wheels. As far as total processing, this is a very critical operation. There are many key steps, all of which make or break the operation. First know the alloy designation, if that is possible. For example many aluminum wheels are 380 series castings or 6061T6. In a condensed form this would be a typical cycle: 1. strip organic coatings (paints, lacquers, primers) either in a chemical solution or by sand blasting. 2.buff and polish to develop desired reflective finish. Remember if these are reprocess wheels, surface nicks, corrosion pits will have to be leveled out. 3.clean either by soak or spray in a chemical detergent bath to remove residual buffing and polishing residues. Best to use a non etch cleaner. 4.soak clean in a non etch, alkaline cleaner. 5.acid etch to remove just the necessary skin of aluminum. This is very important so as minimize the generation of metallic oxide smuts. Also it's a lot better to preserve the high luster of preceding polishing operation. 6.deoxidize and desmut in a tri acid bath. It consists of nitric, sulfuric, and hydrofluoric acids. This maximizes dissolving all residue of metallic smuts from the previous operation. Remember not knowing the exact alloy designation, this is a critical step. Another benefit is this tri-acid formula produces a desired fine porosity on the wheel surface. This enhances adhesion of the subsequent zincate. 7. Now ready to zincate. It's preferred to use an alloy zincate formula, as it preferentially develops a thin, tightly bound and adherent zincate film. It also is self limiting in thickness, preventing slough off. 8. strip the zincate in 50%nitric acid. It doesn't all strip. The function here is to take advantage of the thin zincate layer which remains as a seed for the second zincate film to build on, improving yet adhesion of zincate to base aluminum. 9.Strike plate. Use either of cyanide copper strike, Watts nickel strike, entering live in both plating solutions. The preferred option here is to alkaline electroless nickel strike. The dip provides coverage to all exposed, zincated surfaces. In essence the ultimate service life of the wheel is enhanced, knowing that uniform thickness of the EN strike deposit is present over all surfaces. Incidentally, the EN strike deposit provides approx. 20 to 30 millionths of deposit thickness. 10. Acid Copper plate to provide a thick rapidly leveling deposit that can be buffed due to it's excellent characteristics to buffability. Clean & activate wheel in sulfuric acid, then plate additional acid copper, after the buffing operation. 11. Next, plate with duplex nickel as Ted Mooney had discussed A 75% to 25% composition of semi bright to bright nickel is a good target. This will generally provide a step of 120 to 150 mV. 12. chrome plate as per my message to Ted Mooney. As you can appreciate the cycle is large, neccesitating ample equipment and process tanks. Of course I left out rinsing which is very important between all the process tanks. Doing it right is very important, since the cost to strip and re plate rejects can easily triple the cost to do it right. SFR

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Msg. #5398 in ** Ask Plater B**
Posted on 07/21/94 at 07:22:12
To: ALL From: PAUL PETERSON - Immersion copper on electrolytic nickel Has anyone ever observed immersion deposits of copper onto nickel plated materials? We currently nickel plate a copper grid assembly which is subsequently tested with a phosphoric/citric acid solution. This grid is assembled in a way where each piece is interleaved over the intersecting pieces. At these interleave areas the tolerance is so tight that nickel is not depositing thus leaving raw copper exposed to this acid test solution. I feel this test solution is dissolving this exposed copper and subsequently immersion depositing it onto the nickel surface. Until now, I had never observed immersion deposits of copper onto nickel. Does anyone have a feel for what may be causing this?

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Msg. #5399 in ** Ask Plater B**
Posted on 07/22/94 at 08:02:03
To: PAUL PETERSON From: STEVE RUDY - Reply To 'Immersion copper on electrolytic nickel'
I too have not experienced immersion copper deposits on electrolytic nickel. The problem description indicates that sufficient low current density nickel coverage over the copper substrate is lacking. Check the wet analysis of the nickel bath. Does it conform to desired concentration ranges of inorganic and organic components? Also consider if the targeted chemical profile of the bath is appropriate for the stated plating objective. Is brightness or leveling needed? Does stress figure in the deposit characteristics? What is the service life intention of the part? Also confirm that racking geometry and contacts to part are optimized. Is the nickel plating cycle sufficient? Enough current? With regard to cleaning and activation, is there a scale or welded area in the problem area that is not being removed? Could inadequate rinsing or entrapped solution be causing a slow bleed-out from this connection? These are some of the parameters to consider in order to optimize plating nickel in the described area. If the nagging problem persists, you might consider an electroless nickel strike before the electrolytic nickel. SFR

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Msg. #5406 in ** Ask Plater B**
Posted on 07/22/94 at 21:19:55
To: PAUL PETERSON From: BERL STEIN - Reply To 'Immersion copper on electrolytic nickel'
Paul: Immersion copper on nickel plated articles is a pretty common occurence that can be observed in Ni plating baths on items left in a Cu contaminated solution for 10-12 hours without current. I used to plate similarly looking steel parts with Ni and was not able to get good coverage in the interleave areas in a bright Ni bath. The problem was solved by introducing a semi-bright Ni undercoating. Also, the solutions had to be maintained in tip-top shape by continuous low-current density dummying (pretty easy to do in almost any tank, call me if you need details) to prevent the accumulation of undesirables (impurities, affecting bath performance in the low CD areas). Another possible explanation of your problem might lie in the porosity of your Ni, which could be caused by poor surface preparation and, again, contaminants in the solution. I personally feel that a low-additives undercoating will solve your problem. Good luck, Plater B

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Msg. #5407 in ** Ask Plater B**
Posted on 07/23/94 at 08:30:39
To: BERL STEIN From: PAUL PETERSON - Reply To 'Immersion copper on electrolytic nickel'
Berl: Thanks for the information. After looking into this I too am finding that immersion copper on electrolytic nickel is not unusual. The speed and degree of copper immersion seems to be directly related to the freshness or activity of the nickel deposit. One of our suppliers has done extensive work on this and he has seen that electroless nickel does not allow the immersion deposit. He also tried a new watts bath with only the carrier brightener (class I), and no class II additives and found about the same degree of immersion copper. What is your feeling regarding the electroless nickel?

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Msg. #5409 in ** Ask Plater B**
Posted on 07/23/94 at 22:41:25
To: PAUL PETERSON From: BERL STEIN - Reply To 'Immersion copper on electrolytic nickel'
Paul: I personally like baths with an indefinite life. Anything that has to be disposed of periodically should not be used, unless it is an absolute must. In your case, I think you can do with a semi-bright nickel underplate, no intermediate rinsing, then your final bright Ni. This process is very simple, easy to maintain and reliable. However, if you feel that e/less Ni would not be too much of a hassle in your case
- give it a try. Another argument against it is cost, unless the volume is such that it does not matter. Good luck, Plater B

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Msg. #5464 in ** Ask Plater B**
Posted on 08/13/94 at 16:58:38
To: ALL From: MARTIN GORNSTEIN - BROWN STAINS IN LACQUER OVER BRASS PLATE WHAT ARE THE MOST COMMON CAUSES OF BROWNISH STAINS IN THE LACQUER OVER A BRITE NICKEL BRASS FINISH ON STEEL? OUR PLATERS APPEAR TO RUN INTO THIS PROBLEM ON A REGULAR BASIS AND KEEP TELLING US THEY DON'T KNOW THE REASON FOR THE DISCOLORATION. ANY SUGGESTIONS?

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Msg. #5465 in ** Ask Plater B**
Posted on 08/13/94 at 18:33:41
To: MARTIN GORNSTEIN From: TED MOONEY - Reply To 'BROWN STAINS IN LACQUER OVER BRASS PLATE'
Without seeing the parts I would guess that the discoloration is not actually in the lacquer, but in the brass finish. Almost all brass finishes are cyanide-based; and weeping-out and staining are traditionally a very common problem. If the parts are either cast (so they may have pores to hold solution), or if they include spot welds (such that joints hold solution by capillary action), then I'd be almost sure it was this well-known "cyanide spot-out". But if it is hardware or simple stampings of steel, I wouldn't have expected the problem. The solution is usually better final rinsing: hot & cold, neutralizing, D.I. water, or something to make sure no free cyanide-bearing solution remains. /s

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Msg. #5483 in ** Ask Plater B**
Posted on 08/22/94 at 16:59:48
To: TED MOONEY From: STEVE RUDY - Reply To 'BROWN STAINS IN LACQUER OVER BRASS PLATE'
The spotting out problem described is especially prevalent in summer weather, humid conditions. The optimum post rinsing corrective measure is alternate hot and cold rinsing. This in effect promotes a capillary action on the surface, pushing out the entrapped cyanide solutions. SFR

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Msg. #5564 in ** Ask Plater B**
Posted on 09/11/94 at 23:17:09
To: BERL STEIN From: TED MOONEY - Reply To 'Chrome-like finish?'
Berl, I received a fax from a caller who likes the cobalt process so much he doesn't want his name published for fear he'll be on the phone all day. In his fax he claims to have been using it for a year for millions of screwdrivers and wrenches.

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Msg. #5567 in ** Ask Plater B**
Posted on 09/12/94 at 20:49:04
To: TED MOONEY From: BERL STEIN - Reply To 'Chrome-like finish?'
What cobalt process, Ted, the one promoted by Enthone? Interesting, but it sounded as really concentrated cobalty stuff. I know that the same mechanical properties can be achieved with much less Co and, therefore, a lot cheaper. Berl

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Msg. #5568 in ** Ask Plater B**
Posted on 09/12/94 at 22:27:44
To: BERL STEIN From: TED MOONEY - Reply To 'Chrome-like finish?'
Apparently the Enthone process. I don't really know since I didn't mention brands in the article but he said he was using the one I was thinking of.

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Msg. #5712 in ** Ask Plater B**
Posted on 11/16/94 at 12:52:27
To: ALL From: RON LANDRETTE - questions I have 2 customer problems to put up for discussion 1] a customer recently purchased a 316 s.s. barrel for black oxide,the customer reports the barrel is being attacked. I've sold steel ones in the past that lasted for years,any input? 2] a customer has a plating line that they are using a sealer as a final bath,after reloading the barrel ,first stop is the cleaner,which activates with the leftover sealer to form a deposit in the barrel holes,anyone else have experience with this?

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Msg. #5715 in ** Ask Plater B**
Posted on 11/18/94 at 00:37:17
To: RON LANDRETTE From: RUDOLF SEDLAK - Reply To 'More questions about your questions'
About your 316 ss barrel being attacked by the black oxide, 316 depends on the oxide film on it for protection, if the customer is using water with a high Chloride or even perhaps Flouride content to makeup bath, this could make the bath corrosive as hell. Is this possibly different at this location than others you have experienced? Re: deposit formed by reaction of sealer with cleaner, need more info on what you are calling sealer. Sealer for what? Anodize? Chromate? Etc. Quote from MSDS to give us an idea of what is in sealer. The obvious answer is to rinse better, but maybe this is too simple. Rudy Sedlak

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Msg. #5716 in ** Ask Plater B**
Posted on 11/18/94 at 14:14:54
To: RUDOLF SEDLAK From: RON LANDRETTE - Reply To 'More questions about your questions'
THIS "SEALER" IS BEING APPLIED AFTER nickel plate and ,to the best of my knowledge,is not rinsed off. I do not have the details, nor msds, on the solution nor its makeup.

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Msg. #5752 in ** Ask Plater B**
Posted on 11/23/94 at 02:06:35
To: RON LANDRETTE From: RUDOLF SEDLAK - Reply To 'More questions about your questions'
This lack of knowledge about makeup of sealer is a serious handicap, however, we must press on. Presume it is not possible to rinse barrels after sealer, and before they start cycle again, this is too obvious. If Sealer is acidic, and cleaner contains soap, which many good soak cleaners do, sealer could be setting up soap as fatty acid residue, alternately, if deposit is really really tough to remove, it could be a fatty acid heavy metal soap. This would require serious chelation to remove. Have you tried alternate alkaline cleaners just to remove scale? Perhaps an alkaline derust/descale might cut this stuff. Typically alkaline derust are heavily chelated. Could you give us an idea of what the line is plating, and what the process steps are? Rudy Sedlak

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Msg. #5758 in ** Ask Plater B**
Posted on 11/23/94 at 10:21:01
To: RUDOLF SEDLAK From: RON LANDRETTE - Reply To 'More questions about your questions'
I know it's a nickel barrel line,but thats about it,I will forward your suggestion on the cleaner bath to the shop in question for input

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Msg. #5794 in ** Ask Plater B**
Posted on 12/01/94 at 08:20:46
To: RUDOLF SEDLAK From: STEVE RUDY - Reply To 'More questions about your questions'
Ron, I agree with Rudy, in that more information is needed, to determine how to remove the film. What active chemistry is the film? Is it the right type of process to coat the parts? Looking forward to more information. SFR

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Msg. #5795 in ** Ask Plater B**
Posted on 12/01/94 at 08:28:11
To: RON LANDRETTE From: STEVE RUDY - Reply To 'questions'
Question 1: The stainless steel barrel you mentioned, does it process the black oxidizing of parts in a steel tank? Are the parts being processed steel? If so, an electrical potential has developed between stainless and the process being run. You can probably confirm this by black oxidizing the parts, if shape conforms to a suitably sized Pyrex beaker. Question 2: From the description, residue of the sealer has reacted with the alkaline cleaner. What is the sealer and cleaner chemistries? SFR

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Msg. #5802 in ** Ask Plater B**
Posted on 12/02/94 at 16:33:03
To: STEVE RUDY From: RON LANDRETTE - Reply To 'More questions about your questions'
Well ,the customer isn't too interested in providing any details,so my guess would be he's doing something a little different from the normal. They seem to be happy for the moment by going to an acid tank to remove the "film" Will follow with more when I have it.

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Msg. #6033 in ** Ask Plater B**
Posted on 01/12/95 at 21:57:43
To: ALL From: VALENTINUS BRINKMANN - chrome problem One of my customers has an intermittent problem. In an automatic tank plating chrome on plastic, the bottom parts(many small parts ona large rack) occasionally get grey or foggy in sections. The rectifier is not turned on till the rack is fully immersed and turned off before removal. I checked the rectifier for excessive ripple and it was well within limits. Any ideas?

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Msg. #6035 in ** Ask Plater B**
Posted on 01/13/95 at 14:49:42
To: VALENTINUS BRINKMANN From: RON LANDRETTE - Reply To 'chrome problem'
Val, I'm sure your familiar with chrome burn,but that doesn't seem to be what you are describing. I once ran a Cu/Ni/chrome line and got a similar reaction on "j" bends at the ends from incomplete coverage. with a good bright nickel under the chrome it left a similar effect I don't know the underlying finish on your plastic. check it out

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Msg. #6037 in ** Ask Plater B**
Posted on 01/14/95 at 00:16:54
To: RON LANDRETTE From: TED MOONEY - Reply To 'chrome problem'
I think a picture might be worth a thousand words on this one. Could be chrome burn due to the temperature at the bottom of the tank being cold at startup with no agitation. Could be the opposite. Could be a milky chrome or a milky nickel. Could be nickel burn. And probably a hundred other things. If it is really as sporadic as reported, and fixes itself, you have to suspect temperature or contact, rather than chemical balance, I would think.

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Msg. #6041 in ** Ask Plater B**
Posted on 01/14/95 at 10:47:22
To: VALENTINUS BRINKMANN From: TOM PULLIZZI - Reply To 'chrome problem'
strip the chrome, is the defect still there? is the defect restricted to any current density area? are the parts above, below, or even with the bottom of the anodes? check all solutions on this one, are there anodes in the electrocleaner (cathodes)? or do they use the tank walls?

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Msg. #6042 in ** Ask Plater B**
Posted on 01/14/95 at 18:55:21
To: TOM PULLIZZI From: TOM PULLIZZI - Reply To 'chrome problem'
check the bottoms of the racks for peeling plastisol, check the rack tips for excess buildup

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Msg. #6370 in ** Ask Plater B**
Posted on 03/30/95 at 15:23:24
To: ALL From: JERRY GIRA - burn marks on plated parts Does anyone have an explanation for burn marks showing up on plated tubing in a rack process? What are "danglers" and how do they relate to this problem? This defect occurs on a high number of parts from our supplier and it looks bad. What is the remedy?

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Msg. #6371 in ** Ask Plater B**
Posted on 03/30/95 at 16:24:34
To: JERRY GIRA From: TED MOONEY - Reply To 'burn marks on plated parts'
Danglers are the flexible cables in plating barrels which conduct electricity into the pile of work. The term has no applicability in rack plating. True burns are usually a gritty, sugary, area on the part and occur in the area of highest current density (outside corners, outside bends, edges, parts nearest the anodes). The cause is trying to plate at a current density that cannot actually be achieved under the real conditions--with the result that substantial amounts of hydrogen are evolved because there just isn't enough metal in solution right at the problem area to absorb all the electrons provided by the circuit. Aside from reducing the voltage or current (and consequently the plating rate), some solutions are: increase the agitation to help the metal ions at the interface get replaced faster, increase the temperature for the same reason, increase the solution concentration, place scrap metal forms near these corners to absorb the electricity (these are called thieves), and place insulating sheets (like polypro) near these corners to block line-of-sight from anodes to these corners (these are called shields).

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Msg. #6377 in ** Ask Plater B**
Posted on 03/31/95 at 07:52:54
To: TED MOONEY From: KEN ROSENBLUM - Reply To 'burn marks on plated parts'
Besides those reasons mentioned above, another cause of burn marks is poor electrical contact. Chrome plating in particular needs good, firm contact because of the higher voltages involved. Better fixturing would solve the problem. With any plating process, though, if the contact between the rack and part has too little surface area for the amps going through it, the spot may look "burned" or even melted.

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Msg. #6386 in ** Ask Plater B**
Posted on 03/31/95 at 14:08:03
To: TED MOONEY From: RON LANDRETTE - Reply To 'DANGLERS'
Well,the dangler issue settled,my initial reply is changed. I seem to remember slang term for a "growth" on hard chrome parts many years ago as danglers also. Maybe I'm wrong,it was long ago,but if your supplier is talking about danglers in the true sense,your parts may be being ran in barrels.

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Msg. #6576 in ** Ask Plater B**
Posted on 06/03/95 at 08:35:08
To: ALL From: PAUL PETERSON - Discoloration of electrolytic nickel Does anyone have any information on discoloration of nickel versus temperature. We have a customer who would like to know at what temperature will electrolytic nickel over steel start to discolor. The nickel is plated from a standard watts bath.

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Msg. #6577 in ** Ask Plater B**
Posted on 06/04/95 at 11:39:53
To: PAUL PETERSON From: TED MOONEY - Reply To 'Discoloration of electrolytic nickel'
The exhaust pipes on Harley's certainly turn a nifty iridescent purple-yellow, and you can actually "see" the temperature profile as you proceed from the exhaust manifold to the tail pipe. So I suppose you could use thermocouples or temperature dots or an infrared sensing gun to approximate the answer you are looking for. But I haven't seen it in the literature myself. /s

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Msg. #6578 in ** Ask Plater B**
Posted on 06/04/95 at 23:01:00
To: PAUL PETERSON From: BERL STEIN - Reply To 'Discoloration of electrolytic nickel'
Paul: I don't know if anything has been published on that matter, but usually a low-additives Ni e/deposit will withstand up to about 500 Deg.F without discoloration. At some point the deposit starts turning yellowish with oxidation in air (I mean above 500+ Deg.F). Hope this helps, PlaterB

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Msg. #6590 in ** Ask Plater B**
Posted on 06/09/95 at 22:28:12
To: PAUL PETERSON From: KEN ROSENBLUM - Reply To 'Discoloration of electrolytic nickel'
There probably isn't ONE temperature at which nickel starts to discolor. I'm sure discoloration is also affected by humidity, pH, particulate matter in the air, light, etc.etc.

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Msg. #6638 in ** Ask Plater B**
Posted on 07/08/95 at 12:13:10
To: ALL From: GREG WATKINS - Lead contamination I have been trying to lower the lead concentration in an alkaline copper bath. It was at 44 ppm until I ran a high current/small surface area dummy with an anode bag to catch the fall. It is now all the way down to 38 ppm, still a long way from zero! Any lead removal methods other than making a new bath would be helpful. Thanks, Greg.

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