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Whitewash" on Chrome Plate



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Current postings:

June 6, 2022 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I am electroplating nickel-chrome and it was working good but suddenly all products come out from chrome with white washing defects; the problem is not constant and sometimes disappears, but most of the time I face the white washing problem.

1963-1

After the nickel tank there are 2 dipping tanks, then 2 running water tanks then 1 cathode activation tank then 1 running water tank and 1 has NFDS with no electricity total of 7 tanks before the chrome. The products enter the chrome tank with low electricity rectifier max 50 A then high electricity rectifier. The product stays 4 minutes in the chrome tank. It takes 7 minutes between the nickel and chrome tanks.
Chrome concentration 300 gram per liter
Sulphuric 1.4 gram per liter
Chrome tank temperature 40 °F

Mohamed salah
- Milano Italy
^


June 2022

A. Hi Mohamed.
We added your question to one of two long threads we already have on the subject. If you are running a conventional Sergeant bath with no fluoride, the sulphate is way too low.

My own personal experience doesn't include an activation tank between nickel and chrome, and I don't know what NFDS means. Without that activation (and I don't know how well it works) 7 minutes would certainly be way too long. 4 minutes is a lot of decorative chrome, but probably not the problem. The temperature seems low; I am not familiar with chrome plating at lower than 110 °F (443.3 °C).

I think Hull Cell plating, but emulating your current situation as well as practical, might be revealing.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


June 7, 2022

A. Are you stripping the rack tips? Rack tips that are piled on with heavy nickel, partially non-adherent because of chrome in between, will cause "white wash".

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
probertbanner
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Closely related Q&A's, oldest first:

1998

I've been hearing a lot about "whitewash" on chrome plating recently and haven't been able to find much information about it in our literature. Could anyone give me more information about it? What is it? What causes it? What steps can be taken to avoid it?

Pam Schleicher
^


1998

Dear Pam ,

"Whitewash" on Chrome plate can be caused by many factors , but the most common cause is too much "brightener" in the Nickel Plating solution .

I suggest that you have your supplier check the levels of brightener , leveler & carrier in your Bright Nickel solution and if necessary run them down or dilute the bath .

I would also suggest that the frequency of cleaning & repacking your filters with carbon & filter-aid be reassessed and done more frequently .

Other causes can be "Bi-polar" effect caused by stray currents in the plating bath , poor pH control , poor temperature control ,

Regards

John Tenison-Woods
John Tenison - Woods
- Victoria Australia
^


1998

I think that it is also referred to as milky plate.
It is caused by plating out of tolerances for that tank. Normally milky plate is quite poor and is much softer than "normal".
Temperature out of spec for the amperage it was plated at is probably the most likely cause.
Chromic to catalyst out of balance could cause it.
Bad connections causing much less of the amperage to get to the part could be a culprit also.

James Watts
- Navarre, Florida
^


1998

There are a lot of things that cause white wash. I would bet on the steps between nickel plating and the chromium plating bath rather then imbalance chromium plating solution.

Drag out tanks often cause white wash.

Long periods between nickel and chromium, staying in the chromium solution without current for some seconds etc, also cause white wash.

A cyanide cathodic cleaner between nickel and chromium often solves the problem.

sara michaeli
sara michaeli signature
Sara Michaeli
Tel-Aviv-Yafo, Israel
^



We merged some threads on this page. Please forgive what may look like disrespect of earlier responses; they weren't here :-)



2002

PROBLEM: PARTS COME OUT FROM CHROME TANK ,WHITE CLOUDY AT LOW CURRENT DESITY AREA. WE HAVE NICKEL ACTIVATOR AND CHROME PREDIP BEFORE PARTS GO TO THE CHROME TANK.

popat patel
Popatbhai B. Patel
electroplating consultant - Roseville, Michigan
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2002

Start with the basics:

1. Analyze or have analyzed your plating bath. Check the chrome level and sulfate ratio. Depending upon whether or not this is a proprietary bath, the correct number will vary.
2. Have the level of chloride in the chrome tank checked. It should be at less than 100 ppm
3. Check for good electrical contact, current should be on (HOT) when parts are placed in the tank.
4. Use an auto-ramping rectifier or manually ramp current to initialize plating.
5. Check anodes - should have a uniform brown film.
6. Check for drag over of activator.

After doing the above, do you still have a problem? If so, list specifics.

Gene Packman
process supplier - Great Neck, New York
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2002

White wash on nickel is a known problem. Do you have a drag out tank after the nickel? If positive, try to skip it. The nickel activator, when did you last made up a new activator? As for chrome predip, not more than 10 g/l CRO3 otherwise it passivated the nickel. I hope that parts do not stay in the chrome plating solution without current. Last but not least, ask your supplier for an electrolytic nickel activation.

sara michaeli
sara michaeli signature
Sara Michaeli
Tel-Aviv-Yafo, Israel
^


2002

Popat,

Check your leveling additive, brightener and pH range.

Sincerely,

Anders Sundman
Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden

^


2003

A. White wash usually comes from the rinses between the nickel and the chrome bath. Try to skip them and instead of your rinses, just rinse parts in clean water. Make the time between the nickel and chromium solutions as short as possible.

sara michaeli
sara michaeli signature
Sara Michaeli
Tel-Aviv-Yafo, Israel
^



We merged some threads on this page. Please forgive what may look like disrespect of earlier responses; they weren't here :-)



2007

What causes white wash deposit on wheels after chrome plating aside from low ratio of Chromic acid to Sulfate concentrations in Chrome solution?

Thank you.

Louie Rumbaugh
Lab Supervisor - Carson, California
^

Ed. note: Send a good photo to mooney@finishing.com if you can, Louis. Maybe what you are calling 'white wash' someone else might call haze (or maybe not).


2007

If by deposit you mean a salt layer, will it wash off with DI water? If it is and it has been baked on, it may take a very dilute acid to get it off.
My guess is that it is a haze or milky plate which can also be caused by the amperage either too high or too low for the tank temperature; or another catalyst that you might be using being too low.

James Watts
- Navarre, Florida
^


2007

Might we not be looking at a passive nickel problem, requiring cathodic activation in acid or cyanide prior to chrome plating.

Geoffrey Whitelaw
Geoffrey Whitelaw
- Port Melbourne, Australia
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2007

Try two simple fixes first -

1. Improve rinsing after nickel.

2. Let the part come to temperature for a short time after immersion in the chrome solution before applying current.

jeffrey holmes
Jeffrey Holmes, CEF
Spartanburg, South Carolina
^



We merged some threads on this page. Please forgive what may look like disrespect of earlier responses; they weren't here :-)



2007

Hi, I work in the plating shop for a commercial lock and hardware company. We have been seeing some white wash on some of the parts after they come out of the chrome tank. No matter how low we turn the current it still appears. Some parts we run just get nickel plating, but they still pass through the chrome tank ( with no current ) and they come out fine. It is driving us nuts. Could it be an issue with the nickel bath? Or is it more likely in the chrome? Any suggestions would be very helpful.

Thanx

Brad Standifer
barrel line, rack line operator - Lenoir City, Tennessee, U.S.A.
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2007

This is a frustrating situation that is easily fixed. We had this once and found out that with the addition of sulphuric acid, it went away almost instantly. Please check with your supplier but basically the ph may be too high.

Simon Coates
- Perth, Australia
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First of three simultaneous responses -- 2007

Firstly, white wash is in the eye of the beholder. By this I mean that many plating defects that leave a visible haze after chromium plating are called whitewash by some.

Of those which cause a milky white haze some of these problems may be eliminated by getting an analysis of your bath. Out of ration sulfate/chrome can cause a white haze. So can chloride contamination, low catalyst, high trivalent chromium, etc.

Other sources of similar problems are bath temperature, anode condition, electrical connections, current ripple, passive nickel, grease & oil, etc.

It is best to have a knowledgeable person check your bath and run test panels. Even better if this person could look at work being produced too.

Gene Packman
process supplier - Great Neck, New York
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Second of three simultaneous responses -- 2007

I will start out on the premise that you are analyzing all of your tanks on a regular basis and the chemical composition remains within normal specifications. If not, analyze more frequently.
Milky coloration of chrome in a standard chrome sulfuric acid plating tank is almost always caused by the wrong current density for the temperature of the chrome tank. What ASF and temperature are you using? In the interim, if you are using 110 -120-F try raising the temp 5 degrees and see what happens.

James Watts
- Navarre, Florida
^


Third of three simultaneous responses -- 2007

It's quite possible that adding some sulfuric will fix your problem. But, to confirm this, and determine how much to add, an analysis would be a good idea. Also, you don't say whether you are running a sulfate only bath, or a "mixed catalyst" bath. That makes a difference in the ratio of sulfate to chromic acid used to get optimum results.

Best of all; have a Hull Cell run on the bath as is, then make the addition in the cell, first, and see what the plates look like.

It is difficult to find a lab that does Hull Cell work, sometimes. There is one in our area, Chemionic Labs and Consulting, of New Brunswick, NJ, that does.

dave wichern
Dave Wichern
Consultant - The Bronx, New York
^

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Ed. note: If still more insights are wanted, please see thread 21467

"Whitewash on Bright Nickel/Chrome Plated Parts" none
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