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.
Msg. #4663 in ** Ask Plater B**
Posted on 01/22/94 at 17:25:22
To: ALL From: JON QUIRT
- Bipolar on diode leads. I'm still kicking this problem around. The diodes are 20/1000 dia. and 2.2" long they are nickel struck and the tin/lead plated. The nickel covers all the lead but the tin/lead will on a number of parts in the load "skip in the low current density area by the diodes body. Turning up the current makes matter worse, indicating bipolarity, also the area of the "skip is oxidized again indicating bipolar. The funny thing is that I saw this before with a matte tin bath on but switching to a bright bath eliminates the problem, In fact simply adding brightener to the bath eliminated the problem! Too bad Mil spec won't allow bright plate. Also of interest is that a load plated in the bright bath which turns out ok and then transferred to the matte bath will show bipolar, more showing the longer the cycle. We have notice that by splitting up the plating cell configuration with different dangler some improvement was noted by this is some what come and go, no real pattern has emerged. The customer is using Sterling barrels, I wonder if the Vib barrel like Technic makes would work better? The longer I'm in this business the less I know. Any one seen this or got Ideas? Rule out cleaning and ripple. Thanks Jon
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Msg. #4664 in ** Ask Plater B**
Posted on 01/22/94 at 23:14:49
To: JON QUIRT From: BERL STEIN
- Reply To 'Bipolar on diode leads.'
Jon, I have to agree, everything in your description points to a bipolar effect as the cause of your rejects. If so, there are several approaches one could try to alleviate it. First, try slowing the barrel down to slow down the tumbling of the parts. Next, you can try using an oblique rather than a horizontal barrel so your parts slide rather than tumble. And third, try modifying the electrolyte composition to prevent or slow down the anodic dissolution of your deposit (I suspect that brighteners in the bright bath do exactly that). If you talk to your chemistry vendor, they might suggest an approach for slowing down the deposit anodic dissolution). Using a very low current density might also help by lowering the anodic potential the parts will see. We have a used small vibrobarrel that we would gladly sell you, but my experience (see the same article I mentioned earlier) tells me that the vibratory technique is much more prone to bipolarity. Plater B
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Msg. #4691 in ** Ask Plater B**
Posted on 01/25/94 at 20:54:04
To: BERL STEIN From: JON QUIRT
- Reply on bipolar on diodes. Dear Berl, Thank you for your continue input on this subject. First of my customer is interest in the vibrabarrel, please rely, size. age, make, prior use, price, etc. On the subject of the diodes. I assisted in the setting up of a test bath supplied by one of my suppliers. This bath is the bright formulation. We found that by running the carrier or wetter component we still had bipolar conditions, however on adding 0.0112% brightener (1/10 suggested) no bipolarity was found. A one amp hull cell had just a bright band in the upper HDC. This must be just enough to shift the polarity of the cathode....love those organics.. which of course must be closely monitored for Mil-Spec work. Solderability after thermal bake and steam age was excellent. It was also discovered that some of the hit and miss results we were getting was traced back to the test parts being plated. For test loads customer has a bag of scrap diodes to play with, turns out the bag being used was a group of "seal dummies" they don"t have a semiconductor chip in them and hence conduct current equally well in both directions. This was a fun one...NOT. Hope to hear from you.
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Msg. #4703 in ** Ask Plater B**
Posted on 01/28/94 at 07:55:37
To: JON QUIRT From: BERL STEIN
- Reply To 'Reply on bipolar on diodes.'
Jon, our used unit is an ECI Technologies VIBARREL V-100, with a 3.5" basket. You can purchase an additional 6" I.D. basket from ECI
(201-773-8686). The unit was bought in 1991 for $3,100. How much Servometer will ask for it now, I don't know but will try to find out. It was not used in production
- only for testing, and the total number of hours the unit logged is probably less than 30. You can call me with any additional questions at 201-785-4630. Cheers, Plater B
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Msg. #4770 in ** Ask Plater B**
Posted on 02/06/94 at 20:53:47
To: BERL STEIN From: ROBERT TEICHMANN
- Reply To 'Reply on bipolar on diodes.'
Berl, Why don't you just sell it for the best offer? Bob T
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Msg. #5298 in ** Ask Plater B**
Posted on 06/11/94 at 22:42:53
To: ALL From: BERL STEIN
- Designations for Coatings Here is a thousand dollar question for you
- is there a general standard
(ASTM or otherwise), according to which metallic (and Non-) coatings have to be called out on engineering drawings? If memory serves, in Russia and Europe, too, we had something almost all-embracing. Do we have such a thing in this country? Plater B P.S. If we don't, why don't we introduce one
- it could make life a lot easier for some of us?
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Msg. #5299 in ** Ask Plater B**
Posted on 06/11/94 at 22:51:26
To: BERL STEIN From: TED MOONEY
- Reply To 'Designations for Coatings'
No coating standards MUST be specified on drawings, but there are dozens of ASTM and MIL specs for different coatings. I guess I don't quite understand the question.
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Msg. #5300 in ** Ask Plater B**
Posted on 06/13/94 at 07:09:55
To: TED MOONEY From: BERL STEIN
- Reply To 'Designations for Coatings'
The question was whether there exists a single all-embracing document specifying how coatings should be called out on prints. Your answer is, if I read it correctly, "No", which is a pity. A lot of non-platers do not understand these things too well, and, if my Russian experience is of any use, like to rely on something fairly basic for guidance. That's why, I guess, they have such a document over in Russia and, I think, Europe, too. Plater B
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Msg. #5318 in ** Ask Plater B**
Posted on 06/22/94 at 07:26:37
To: ALL From: PAUL PETERSON
- Origin of the term Mil Does anyone know how the term MIL came to be equal to one-thousandth of an inch? How many people are using metric units in specifications and certifications?
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Msg. #5321 in ** Ask Plater B**
Posted on 06/22/94 at 08:01:33
To: PAUL PETERSON From: TED MOONEY
- Reply To 'Origin of the term Mil'
Mil is in the dictionary, so it is an accepted term, not just industry slang. Milli means "one-thousandth", so I'd guess we needed and used the term milli-inch until usage foreshortened it.
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Msg. #5821 in ** Ask Plater B**
Posted on 12/05/94 at 22:02:16
To: ALL From: BETSY RUSTON (FAX)
- Meaning of "Class A" We are very familiar with the concept of "Class A" for excellent finishes of plastics/composites. How does that idea of "Class A" finishes translate into the world of finishing of aluminum sheet metal? We would appreciate your ideas on directions to go for the most authoritative sources. Many thanks!
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Msg. #5824 in ** Ask Plater B**
Posted on 12/07/94 at 08:03:16
To: RON LANDRETTE From: STEVE RUDY
- Reply To 'More questions about your questions'
If the film is removed in the acid, it's usually a good sign, with regard to cleaning and activation. I'll stay tuned for more updates. SFR
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Msg. #5831 in ** Ask Plater B**
Posted on 12/07/94 at 22:11:49
To: BETSY RUSTON (FAX) From: BERL STEIN
- Reply To 'Meaning of "Class A"'
Well, Betsy, perhaps you should tell us a little more about what exactly
"Class A" finish means, for in the whole volume of ASTM standards on plating (vol.02.05) I found no mentioning of "Class A" finish or, for that matter, no particular finish class at all. Which is, indeed, surprising. The world could probably use some solid criteria for rating plated surfaces, but, alas, there aren't any in the ASTM book. Cheers from PlaterB
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Msg. #5838 in ** Ask Plater B**
Posted on 12/08/94 at 09:00:45
To: KEN ROSENBLUM From: TED MOONEY
- Reply To 'ALUMINUM PLATING'
I've seen the literature for this process, the Sigal process. It's available from New Materials Corp in Coon Rapids, Minn. (you probably already knew that). But I don't have any hands-on knowledge of it, nor the answers to your questions.
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Msg. #5839 in ** Ask Plater B**
Posted on 12/08/94 at 09:08:00
To: BETSY RUSTON (FAX) From: TED MOONEY
- Reply To 'Meaning of "Class A"'
I'm not aware of any formal meaning to the phrase "Class A". I think it's similar to "best commercial practice"--just slang that means "we expect you to do a good job". I don't know that it has any legal implication. I think you can, without embarrassment, ask the customer exactly what s/he means by it and what s/he is looking for.
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Msg. #5848 in ** Ask Plater B**
Posted on 12/09/94 at 13:38:26
To: BERL STEIN From: RON LANDRETTE
- Reply To 'Meaning of "Class A"'
aS FAR AS PLATING SPECS GO,I don't know about ASTM, but I used to plate to mil spec and qqp spec,they're pretty specific
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Msg. #5869 in ** Ask Plater B**
Posted on 12/11/94 at 21:29:18
To: RON LANDRETTE From: KEN ROSENBLUM
- Reply To 'Meaning of "Class A"'
Mil specs are only specific as to the functionality of the plating finish
(thickness, adhesion, embrittlement, corrosion properties). They are usually very vague when it comes to the cosmetics of a surface. They usually stick to terms such as "good workmanship" and " free of visible flaws".
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Msg. #5898 in ** Ask Plater B**
Posted on 12/14/94 at 20:16:03
To: ALL From: BERL STEIN
- Coatings/Substrate combinations Does anyone know of a coatings selector guide or chart that would help choose a coating for a given substrate taking into account the substrate/coating galvanic interaction? We used to have something like that in Russia. Thanks, PlaterB
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Msg. #5912 in ** Ask Plater B**
Posted on 12/15/94 at 16:22:49
To: KEN ROSENBLUM From: RON LANDRETTE
- Reply To 'Meaning of "Class A"'
As memory serves,it was common for a finish spec on the prints for many accounts,a sign similar to a square root sign with 32 or a "32 rms" finish I think,its been awhile However,parts plated to mil spec that were not bright enough were routinely returned
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Msg. #5916 in ** Ask Plater B**
Posted on 12/15/94 at 22:53:30
To: RON LANDRETTE From: KEN ROSENBLUM
- Reply To 'Meaning of "Class A"'
Its true that some prints call for surface finishes of a certain microfinish (rms). However, this is only specifies the smoothness of the finish. It does not say anything about the brightness, color, luster, allowance of spots, stains, voids, etc. You can have a very fine microfinish surface that looks looks lousy.
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Msg. #5940 in ** Ask Plater B**
Posted on 12/19/94 at 14:21:04
To: KEN ROSENBLUM From: RON LANDRETTE
- Reply To 'rms microfinish'
In our cnc dept,w have a comparison card for rms microfinish on machining the finer the spec,the closer to mirror it becomes,would'nt this rms be the same for plate?
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Msg. #5946 in ** Ask Plater B**
Posted on 12/19/94 at 21:50:44
To: RON LANDRETTE From: KEN ROSENBLUM
- Reply To 'rms microfinish'
My experience is that rms finish does not always correlate with mirror like quality. Sometimes the microfinish is a lower number, but the finish looks duller ( I don't know why). Also the rms meter won't pick up on stains and spots that don't cause a high or low spot on the surface.
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Msg. #5950 in ** Ask Plater B**
Posted on 12/20/94 at 13:54:13
To: KEN ROSENBLUM From: RON LANDRETTE
- Reply To 'rms microfinish'
not questioning your experience,nor do I have an rms tester,just a comparison card. I wonder if there are different standards for rms machining/plating/others?
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Msg. #5958 in ** Ask Plater B**
Posted on 12/22/94 at 08:09:30
To: RON LANDRETTE From: STEVE RUDY
- Reply To 'rms microfinish'
The rms is a measurement of surface flatness or leveling. My experience in this regard is more toward mass finishing. For example bearings, that may need a very rounded , even finish for the part's application. If the part is to be plated, I would suggest mass finishing with plastic media, incorporating a cutdown and burnish cycle. Perform the rms measurement, then proceed to plating. The part configuration must be conducive to mass mass finishing. In plating, there should not be any roughness in the process baths. Also the brightness & leveling if part of the plated deposit must be optimized. Ductility is very important, as microcracks may not be tolerated. SFR
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Msg. #5963 in ** Ask Plater B**
Posted on 12/28/94 at 20:24:44
To: RON LANDRETTE From: KEN ROSENBLUM
- Reply To 'rms microfinish'
I think that rms means the same thing in all industries. It is a mathematical representation of the contour of a surface.
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Msg. #5968 in ** Ask Plater B**
Posted on 12/29/94 at 09:32:41
To: KEN ROSENBLUM From: RON LANDRETTE
- Reply To 'rms microfinish'
If this is so,then a rms comparison card like what we use here would then apply somehow to plating as well.
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Msg. #6043 in ** Ask Plater B**
Posted on 01/15/95 at 12:31:54
To: ALL From: GORDY SEPPANEN
- Galvanic Series Does anyone have a complete galvanic series on computer? You see periodic charts everywhere but I have never seen a galvanic series in seawater or other conditions on a BBS.
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Msg. #6045 in ** Ask Plater B**
Posted on 01/15/95 at 13:03:31
To: GORDY SEPPANEN From: TED MOONEY
- Reply To 'Galvanic Series'
I haven't seen any either, but if anyone has one that they are confident is in the public domain we'd love to have it here.
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Msg. #6108 in ** Ask Plater B**
Posted on 02/01/95 at 20:04:09
To: ALL From: BERL STEIN
- Again Ripple Finally, I managed to run some tests on the effect ripple has on throwing power. We started with two acid Zn bath, and in both Hull Cell tests produced similar trends
- the higher the ripple, the poorer the throwing power. Deposit appearance was not affected much, except for some burning in the high CD area at the highest (100+%) ripple. Hoping to do some nickel baths next. Predictions, anyone? PlaterB
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Msg. #6110 in ** Ask Plater B**
Posted on 02/01/95 at 23:48:46
To: BERL STEIN From: TED MOONEY
- Reply To 'Again Ripple'
I'll do my predictions in a couple of weeks; a peek is worth a thousand finesses.
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Msg. #6115 in ** Ask Plater B**
Posted on 02/04/95 at 00:32:05
To: TED MOONEY From: RUDOLF SEDLAK
- Reply To 'Galvanic Series'
The concept of a galvanic series that really means anything is a dream. I have been studying this for most of my life, and the problem is that any galvanic series is only valid for a limited and -->very<-- narrow set of conditions. The classic ones are only valid for a given pH, and only for a set of circumstances that the experimenter worked in. Any changes radically and completely can change it. Trivial changes like the presence of Chloride ion will radically change many EMF's. Sometime the addition of certain ligands (read chelates) can reverse the position of two metals in a galvanic series. All of this is because the EMF of a given metal is dependent on the condition it is going to. Or in other words, the more stable the compound it is going to, the greater the tendency for it to go there, and thus the greater the EMF, and the lower on the galvanic series. In order to have a galvanic series, it would change with every electrolyte. This is too tough a concept for most of academia, and only one of the reasons why academia is of so little help for most of us out in the real world of chemistry. This doesn't really help, but it may increase understanding. Rudy Sedlak
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Msg. #6117 in ** Ask Plater B**
Posted on 02/04/95 at 01:20:19
To: RUDOLF SEDLAK From: TED MOONEY
- Reply To 'Galvanic Series'
I won't question the accuracy of your statement, it is surely true. But that does not mean that galvanic series are worthless either, only that a close call can go either way. In the real world that you mention, zinc DOES act as a sacrificial protective layer for steel whereas nickel acts only as a barrier coat and DOES actually accelerate corrosion once the barrier is breached. Conversely, we find that attempts to plate acid copper or nickel onto zinc WILL result in non-adherent immersion deposits, etc. The concept is important, and metals far from each other will maintain their ranking over pretty widely varying conditions.
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Msg. #6123 in ** Ask Plater B**
Posted on 02/06/95 at 18:55:49
To: RUDOLF SEDLAK From: KEN ROSENBLUM
- Reply To 'Galvanic Series'
Aren't EMF's pretty well defined for sea water?
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Msg. #6134 in ** Ask Plater B**
Posted on 02/08/95 at 06:50:31
To: KEN ROSENBLUM From: RUDOLF SEDLAK
- Reply To 'Galvanic Series'
For sea water, yes, but that is a very narrow electrolyte. In other words it does not change to any significant extent. The problem comes with metal combinations like Tin and Copper. In many applications (read electrolytes) Copper will immersion plate on to Tin, but if the electrolyte is acidic, and you add Thiourea, the reverse is true. But if you keep the electrolyte constant, as sea water is, then a true galvanic series can exist. Rudy Sedlak
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Msg. #6258 in ** Ask Plater B**
Posted on 02/26/95 at 13:22:04
To: ALL From: BERL STEIN
- Ripple revisited I uploaded a text file (ZNRIP1.TXT) with my paper on ripple effects in Zn electrolytes. Anybody interested, please read and comment. Criticism is welcome. Cheers from PlaterB
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Msg. #6412 in ** Ask Plater B**
Posted on 04/06/95 at 20:44:40
To: TED MOONEY From: STEVEN STARR
- "Dichronite" or "Microseal" Coatings? I am looking for info on coatings for stainless steel, with the trade names of "Dichronite" or Microseal. Any help would be appreciated.
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Msg. #6417 in ** Ask Plater B**
Posted on 04/10/95 at 23:23:04
To: ALL From: KEN ROSENBLUM
- DRIVE WAX 206 Does anyone know the manufacturer of a product called "Drive Wax 206"? It is applied after zinc plating to prevent galling in fasteners.
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Msg. #6419 in ** Ask Plater B**
Posted on 04/11/95 at 13:01:18
To: KEN ROSENBLUM From: RON LANDRETTE
- Reply To 'DRIVE WAX 206'
I don't know of "rive wax",but "molycote" does the same thing with all fasteners,to experience.
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Msg. #6444 in ** Ask Plater B**
Posted on 04/22/95 at 17:36:32
To: ALL From: BERL STEIN
- Continuous (real-time) stress monitor Has anyone heard recently of an instrument to monitor continuously stress in plating baths? I remember reading something about it a long time ago, can't recall where. Thanks, PlaterB
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Msg. #6445 in ** Ask Plater B**
Posted on 04/23/95 at 11:31:07
To: BERL STEIN From: TOM PULLIZZI
- Reply To 'Continuous (real-time) stress monitor'
not much help, but I did read about it too! some advertisement.
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Msg. #6459 in ** Ask Plater B**
Posted on 04/25/95 at 22:06:28
To: KEN ROSENBLUM From: VALENTINUS BRINKMANN
- Reply To 'DRIVE WAX 206'
Is that made by the same company that makes COOL 154? :)
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Msg. #6464 in ** Ask Plater B**
Posted on 04/26/95 at 23:31:25
To: VALENTINUS BRINKMANN From: KEN ROSENBLUM
- Reply To 'DRIVE WAX 206'
I wish I knew..... s
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Msg. #6511 in ** Ask Plater B**
Posted on 05/08/95 at 17:05:21
To: ALL From: WES THOMPSON
- en stop off micro super xp2000 It appears that Tolber has changed the formulation of their EN stop off micro super xp 2000. It now becomes brittle after exposure to plating conditions. Does anyone know of a replacement that has good adherence but remains peelable and flexible after plating exposure. ...Wes Thompson
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Msg. #6526 in ** Ask Plater B**
Posted on 05/12/95 at 19:53:32
To: WES THOMPSON From: TOM PULLIZZI
- Reply To 'en stop off micro super xp2000'
I don't have a replacement for that EN stop off, but if you could do me a favor.... Please give the Tolber Product Manager this phone number; (609) 361-2272. If a product called EN stop off Miccro Super sp 2000 becomes brittle after exposure to plating conditions, I 'd like to talk to him/her about a consulting job I could do for them. Don't tell them this, but what I would do is call their Sales, Research, and Marketing Managers together into a room, close the door, and say "I Heard That Your EN STOP OFF MICCRO SUPER SP 2000 Becomes Brittle After Exposure To Plating Conditions" and see what happens next.
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Msg. #6566 in ** Ask Plater B**
Posted on 05/30/95 at 09:51:32
To: ALL From: FRANK BETZNER
- POTENTIAL PROBLEMS WITH ZINC FLUX WE ARE A CAPTIVE ZINC DIE CASTING/PLATING FACILITY. WE ARE CURRENTLY INVESTIGATING A POTENTIAL PROBLEM WITH OUR ZINC FLUX. HAS ANYONE ON LINE EXPERIENCED PROBLEMS WITH THE INCORRECT USE OF ZINC FLUXES OR THE USE OF INCORRECT ZINC FLUXES IN REMELT SYSTEMS? OUR SYSTEM CONTAINS APPROXIMATELY
5% REMELT. OUR IN HOUSE TESTING AND ANALYSIS INDICATES THAT A DIFFERENCE I IS DETECTED BETWEEN THE VIRGIN METAL AND THE REMELT, BOTH IN THE REMELT SYSTEM AND IN THE CAST PART. WE ARE EXPERIENCING PITTING AND IRREGULAR PLATING ON THOSE PARTS WITH HIGH CONCENTRATIONS OF THE CONTAMINATE. IF THIS IS A PROBLEM, HOW DOES ONE CORRECT IT? DOES THE SYSTEM HAVE TO BE PRUGED AND VIRGIN MATERIAL INTRODUCED? CAN THE SYSTEM BE CLEANED BY CHANGING THE FLUX MATERIAL? ARE THERE OTHER OPTIONS?
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Msg. #6624 in ** Ask Plater B**
Posted on 06/30/95 at 07:52:24
To: ALL From: TED MOONEY
- Making Current Shunts Solderable Hi, Our company Power Systems, Inc has had serious problems with solderability of small (0.5") alloy wires (10AWG to 24AWG) we use as current shunts for sensing overload and short circuit conditions in our switching power supplies. A temporary solution has been barrel plating a copper strike followed by .0003 -.0005 tin plate. This works until you get to the thin wire gauges. Can you suggest any other solution? The alloy is called Alloy 90. It does not solder well in a no-clean process. Thank You, P. Lopes PJLopes@aol.com
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Msg. #6633 in ** Ask Plater B**
Posted on 07/07/95 at 10:37:21
To: TED MOONEY From: RUDOLF SEDLAK
- Reply To 'Making Current Shunts Solderable'
Do you need to use a no-clean flux for your process? This is one of the more difficult to use processes, and consequently will require a very solderable surface. But to the meat, is Alloy 90 a 90/10 Nickel/Iron alloy, as the name would imply? If so keeping this gem solderable could be a challenge. Probably some sort of plating is mandatory. But it is difficult to plate very small wires. Would you consider immersion plating? If so, we have recently put together an immersion plating bath for Palladium that seems to work well on pure Nickel. If the alloy is what I suspect, this might work well for you. If the alloy is as I suspect, we would be happy to run some samples for you. This finish is inherently not the easiest to solder to in the world, but we have had some no-cleans work well, and the good news is, that if it works well fresh, it will not change solderability characteristics over the next year. Rudy Sedlak RD Chemical rsedlak@aol.com
415-962-8004
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Msg. #6642 in ** Ask Plater B**
Posted on 07/12/95 at 00:55:53
To: TED MOONEY From: RICHARD ZUENDT
- Reply To 'Making Current Shunts SolderableBecause '
Because of the small diameter of the wire, why not consider the use of an immersion tin deposit? This deposit would be about 20-25 microinches in thickness and should provide a solderable surface for an adequate period of time. Further, since it would not involve any aggressive handling, just slight part movement, it would not distort the wire. Hope it helps. Please get back to me if it does. Rich Zuendt
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Msg. #6645 in ** Ask Plater B**
Posted on 07/14/95 at 01:03:53
To: RICHARD ZUENDT From: RUDOLF SEDLAK
- Reply To 'Immersion Tin, on Iron/Nickel alloy?'
Rich, most immersion Tin compounds that I have experience with are spec ific to Copper, and in fact are poisoned by Iron contamination. Are you aware of some that I do not know about, or what>> How are you, and how is my favorite manager? Rudy
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----- Msg. #6627 in ** Ask Plater B**
Posted on 06/30/95 at 07:57:14
To: ALL From: TED MOONEY
- Corrosion of Hot Dipped Zinc Coating We have a number of hot dipped galvanized panels that were stored improperly and have developed "wet storage stain". Most areas are whitish in color, which I understand is zinc hydroxide, but the real question is what is the black staining?
Chemical analysis reveals only zinc and oxygen. I suspected iron would be found incorporated into the black areas, but none was found?
Anyone have any ideas?
Aloha,
Bruce Liebert University of Hawaii
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Msg. #6628 in ** Ask Plater B**
Posted on 06/30/95 at 07:59:05
To: TED MOONEY From: TED MOONEY
- Reply To 'Corrosion of Hot Dipped Zinc Coating'
Aloha, It is believable that you are detecting no iron. While iron-zinc compounds are formed at the interface, they do not extend all the way through the coating; rather the surface of the hot dipped coating is nearly pure zinc. Further, as noted in ASM International's 'Volume
5: Surface Cleaning, Finishing, & Coating', the white corrosion products are about 500 times as voluminous as the zinc metal, and sometimes the damage to the coating is much less severe than it looks; so it is possible that you still are seeing only zinc even after what looks like significant corrosion activity.
It is desirable, and often doable, to remove 'wet storage stains.'
Consult the above-mentioned text or the booklet "Painting Galvanized Structural Steel" by the Zinc Institute and the American Hot Dip Galvanizers Association for guidance.
I don't know what the black stains are, and hopefully a reader who is more knowledgable than me will chime in. But in the meanwhile, is it possible that they are a mildew? I'm no lab technician, but if wiping a test piece with bleach doesn't remove the stain, it would at least prove me wrong.
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Msg. #6629 in ** Ask Plater B**
Posted on 06/30/95 at 16:37:51
To: TED MOONEY From: GEORGE GORECKI
- Reply To 'Corrosion of Hot Dipped Zinc Coating'
Ted, Studies of the corrosion of HDG substrates in automotive applications have shown that typical corrosion products are zinc hydroxychloride and zinc hydroxysulphate. Now, your reader didn't find any chloride or sulphate in his analysis, but then he didn't intend to expose his HDG panels to corrosive environment, either. without knowing the nature of the atmosphere where the panels were stored, it's not easy to determine the nature of the corrosion product. Happy hunting!\
-- GG
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Msg. #6647 in ** Ask Plater B**
Posted on 07/15/95 at 10:15:25
To: ALL From: GREG WATKINS
- berylium-copper I am trying to do a chromate conversion on a BeCu part, followed by a red dye for identification. Has anyone found a good method for this? I have tried several approaches without much success. Any tips would be appreciated. Thanks, Greg.
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Msg. #6648 in ** Ask Plater B**
Posted on 07/16/95 at 22:44:28
To: GREG WATKINS From: TED MOONEY
- Reply To 'berylium-copper'
I have seen dye used very reliably on zinc plated & chromated parts, by simply putting dye in the final hot rinse. However, this was 'metric blue', where a somewhat faint 'pastel'
hue is acceptable.
I'm not sure if the chromate layer on BeCu will be thick enough to give any appreciable color from the dyeing, nor how red you need the parts to be. For example, I don't think you could match the vividness of an anodized aluminum part with a chromated part. Then again, I never tried it; maybe someone else here did?
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Msg. #6649 in ** Ask Plater B**
Posted on 07/16/95 at 22:49:11
To: [1;1ANDREW REID From: TED MOONEY
- Reply To 'Cobalt/Zinc alloy plating'
Such manufacturers as Fred Gumm Chemical, MacDermid, and Enthone-OMI can give you literature on cobalt-zinc processes.
Galvanizing, however, is relatively cheap. If decorative value isn't important, and the presence of gummy corrosion products isn't important, it will probably be difficult to beat galvanizing. Plain zinc plating ought to be an alternative if galvanizing is an alternative, though--no?
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Msg. #6654 in ** Ask Plater B**
Posted on 07/18/95 at 22:01:40
To: TED MOONEY From: GREG WATKINS
- Reply To 'berylium-copper'
Thanks for your reply. I left a part in a soak overnight(degreaser). The next day I rinsed it well and applied a chromate coat followed by the dye. The color took well enough for the color coding it is to be used for. The use of the acid wasn't needed. I'm sure the degrease time can be much reduced. Still working on it. Greg.
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Msg. #6659 in ** Ask Plater B**
Posted on 07/19/95 at 04:36:02
To: ALL From: ANDREW REID
- Heaters and Zinc Alloys Hi. There are a few problems that I was hoping you might be able to help us with.
1) We use sulfuric Acid Pickles which operate at around 40-50 C. We use
415 V (2 active phases) 5 kW Quartz sheath Heaters & are experiencing failures of the ceramic bobbins. What do other people use to heat their pickles, (10-15%v/v)? We have been advised that lead heaters have a limited life, but something has got to be better than heaters lasting a fortnight! The element length in the heaters is 26", and the sheath length is 32".
2) We are also experiencing failures on titanium elements (over the side type), also 5 kW, which are in service on our M&T (ATOTECH) proprietary electro-cleaners. The titanium is being etched
- the heaters are insulated from the tank walls which are used as cathodes. In the past 10 years we have used both Ti and mild steel elements without incident. The manufacturer suggests that Ti should not be used, and recommends Incoloy(R) 825 instead.
3) We would like to hear from anyone who has tried to replace galvanising of fasteners with Zn/Co plating. Local manufacturers are desperate for an alternative to galvanisers, and are keen to know if the corrosion properties of Zn/Co are comparable. We'd like to hear from anybody who has been successful in displacing galvanising. The prices of plating vs. galvanising are comparable in Australia, but authorities specify gal purely from force of habit! Any experience here?
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