A. Hi Rahul. We have attached your inquiry to a long thread discussing the many alternatives. But make sure you very clearly tell your customers that what you are providing is not chrome plating ... not only because a perfect match may not be possible, or the corrosion resistance may not be equal, but because you cannot read the designer's mind and know why chrome plating was specified.

You can certainly suggest alternatives, but the essential step is for the specifier to change the specification, never for a supplier to decide that what they are offering is 'equal' :-)

Luck & Regards,

A. I don't think that's true, Mr. Shaikh, although you may know something that I don't.

A. What's banned is hexavalent chrome, not chromium metal. Chromium metal is not banned.

A. Hi Tommy. It's but difficult to respond to such a broad question. There are at least a dozen books just about chrome plating, and there are indeed numerous possible alternatives, some suitable for certain applications but not for others. Alternatives range from vapor deposition of aluminum with an organic topcoat (which was used on interior plastic parts almost 50 years ago), to sputtering (which was used on some GM cars 3 decades ago), to trivalent chromium replacement for hex chrome, to cobalt replacements for hex chrome, to imitation chrome spray coatings ("chrome-look" paint), to electrolytic lacquers.

Chrome plating is the standard, used almost universally by OEMs. Why do you want to replace it, and in what applications (interior, exterior, tiny parts, bumpers)? Thanks.

A. Virtually anything at all, from a rock to an orchid, can be electroplated, Tommy. The main issue is whether the finish is durable enough and exhibits sufficient adhesion to meet your needs in a specific situation. Most exterior automotive brightwork is nickel-chrome plating on ABS plastic. ABS has the special advantage that it can be etched to develop a very good "tooth" for the plating.

If you are speaking of soft substrates, you also need to recognize that nickel and chrome are hard metals, and are brittle, and will therefore generally crack like your decorative Christmas ball if plated onto a flexible substrate. Chrome plating at all is a difficult multi-step process (please see our Intro to Chrome Plating). Trying to do it on a variety of challenging substrates is a task for a specialty shop with many years of experience.

Chrome is metallic; it is never red, green, or purple. A translucent organic tint can sometimes be successfully electrophoretically applied on top of metallic surfaces, but there are adhesion and durability issues there as well.

What you may be looking for is proprietary organic "chrome-look paint" coatings offered by a number of suppliers including G.J. Nikolas [a finishing.com supporting advertiser] and Gold Touch [a finishing.com supporting advertiser]. These are specialty paints, that can be any color, with very tiny reflective flakes and/or a silver nitrate mirror formulation that flow to form a highly reflective surface. Good luck.

"Nickel and Chromium Plating"
by Dennis & Such

on eBay or

AbeBooks

or Amazon

(affil links)

A. There are alternatives, but when it comes to quality of appearance, nickel-chrome plating is the standard that the alternatives are trying to match. If you are doing nickel-chrome plating and it is less beautiful than something else you have seen, it is because you are not doing the nickel-chrome (or the prep work associated with it) right.

There are alternatives that are cost effective, and there are alternatives that are more environmentally friendly, but none that look or perform quite as good, let alone better.

A. There are proprietary alternatives to the traditional chrome plating layer, such as trivalent chromium and tin-cobalt. Any of the major suppliers of plating processes can introduce you to their proprietary alternatives. These should be satisfactory for automotive industry use, while moving you away from the use of hexavalent chromium, but you would still be doing nickel plating.

Tremendous progress has been made in the last few years on the "chrome-look" paints and "chrome-look" PVD processes. Chrome-look stuff of OEM quality is now routinely applied to wheels and some other items by many of the major automobile manufacturers ... but real chrome plating is still what is done for the brightwork.

A. PVD is an acronym for Physical Vapor Deposition. Usually when people talk about vacuum metallizing they are trying to restrict themselves to mean the one type of PVD that evaporates a thin film of aluminum onto the substrate, and without using any voltage to accelerate the plasma to bombard the substrate to cause an impact for better adhesion. So a vacuum metallizing machine can be less expensive than other PVD chambers.

The thin film of aluminum cannot be left exposed, so it is covered with a thin, specially designed, clear organic topcoat. This is indeed a cheap coating that is used on model cars rather than real cars, although some automobiles used it on interior plastic parts in the 1960s, which made them age as gracefully as a child's toy ring from a gumball machine.

There are much higher quality PVD deposits, some of which require organic topcoats and some of which don't. My knowledge of them is pretty much only book knowledge, but some of our readers like Jim Treglio would have the expertise to be able to further assist you.

A. Silver offers SOME of the qualities of gold, plastic offers SOME of the qualities of wood, and chrome alternatives offer SOME of the qualities of chrome. Nothing offers ALL of the properties of something else or it would be that other thing instead of itself :-)

You are probably speaking about decorative chrome rather than hard chrome, Dean, and one of the alternative coatings that offers a lot of the properties of a chrome topcoat over nickel is a proprietary tin-cobalt plating process offered by the major plating process suppliers. I'm sure that there are a number of shops who offer this, including some of finishing.com's supporting advertisers who will contact you in private.

A. Hi R. It certainly wasn't chrome plating but, sorry, I don't know which brand of "chrome-look" paint it was.

Regards,

A. The "rides" company is Alsa Mirrachrome.

? Ceri,
Green and black chromium?! What do you mean?

A. I think Ceri is referring to green and black chromate conversion coatings (perhaps on zinc). Hopefully he'll get back to us.

A. I presume you are talking about conversion coatings on zinc plate. The finishes you are referring to are the most difficult to find trivalent replacements for. The black is available although every product on the market has some shortcomings in corrosion resistance, bath life, ease of use or cost. The green (I presume this to mean olive drab) has not to my knowledge been able to be formulated as a trivalent material except as a dye color for other chromates. The vast majority of parts processed for this finish must meet military or government specs (in the U.S.) and for this finish no trivalent product is on the QPL (qualified products list).

A. Certainly know of black chrome. It can only really be used for decorative purposes, has little wear or corrosion resistance and has an even poorer throw than conventional chromes.
Must admit that I have never heard of green chrome though.

A. Ceri,

So now we need to know what the substrate you want the paint to stick to. Do you want it to stick to hard chrome? If it is I would suggest an etch primer to start with, followed by an epoxy primer and then probably a polyurethane topcoat.
Do you need paint specifications? If so, do you want US military specifications or UK defense specifications or even BS/ISO specifications?

Give us a prod in the right direction and I'm sure that we will be able to find a suitable answer for you.

A. Ceri,

Assuming you want electrical continuity then electroless nickel is the way to go. Note that there will be some slight drop off in performance due to surface pretreatment. You should talk to the chemical manufacturers such as Atotech if you want RoHS compliant coatings. They make them and will be better able to advise on their use.

There seems to be some confusion on the primer side of things though. Alodine is a conversion coating for Aluminium, not a primer. There are non-hexavalent chromium conversion coatings on the market. Again talk to the manufacturers such as Henkel.
Depending on how you apply the coating there may well be an increase in electrical resistance. If uncertain when calling up the coating you should either call up MIL-C-5541 Class 3 or DEF STAN 03-18 for low electrical resistance.

If you mean paint primers, well that's another story altogether.

A. Maybe you could choose MIL-A-8625 / MIL-PRF-8625 [on DLA] Type III class 2 Black hard anodizing but leave the contact point area bare (by masking).
Doing so you could meet all of the requirements:
i) Conductivity
ii) Salt Corrosion Resistance (500 hours Ideally)
iii) Wear resistance
iv) Colour - Green & Black Ideally

A. Hi Marvin. Here in the USA no plating shop attempts to design their own decorative plating processes, so I have no relevant experience to enable me to make even a guess. But all of the major plating process suppliers have offered alternatives to hexavalent chrome, such as trivalent chromium plating, tin-cobalt, nickel-tungsten, and various other alloys. I think if you contact them, there will be food for thought.

As you know, though, it's not just about color. Chromium plating greatly improves the corrosion resistance of the underlying nickel plating. Topcoats have never been necessary with nickel-chrome plating, but perhaps you can get the color right with your cobalt alternative, and then topcoat with a silicate coating or an organic clearcoat. Good luck.

Regards,

A. I am working on a hybrid between PVD coating process and Electroless Cobalt, I am adapting the PVD basecoat/topcoat system with the Electroless cobalt/nickel metal deposition for wheels, ideally the basecoat/top coat would need to be a UV curing coat that provide a smooth and adherent base for the autocatalytic cobalt or nickel to be deposited without the need to use harmful etching chemicals, and the top coat would need to last for a many years of road abuse, so far the testing has been on a very small scale and automotive basecoat/clearcoat have been used instead (like spray on silver process), I am trying to get around the expensive Palladium activator too.

A. Hi Ali. As you see from the previous postings on this thread, you are asking lots of questions which cannot be thoroughly dispatched in a simple response in a forum, but I can give it a start:
1. No, you can't make nickel look like chrome because all non-precious metals tarnish, and the tarnish on nickel is yellowish.
2. "Safe" is relative. Trivalent chromium plating is probably, per your definition and concerns, "safer" than traditional hexavalent chrome plating.
3. Chrome plating can be way way safer than lots of things medical personnel are exposed to. But handling the air emissions and rinsewater from chrome plating, preventing human exposure, and being certain there are no leaks under any conditions is not an easy thing to do.
4. Talk to local plating process suppliers about their proprietary alternatives to chrome. None are 100% the equal of chrome plating, but they can be very good.

Regards,

A. Hello again Ali. Any reader is welcome to respond, but I don't have the experience or knowledge to guide you through non-proprietary substitutes for chromium plating.

In the USA, the plating industry just doesn't work that way; rather, plating shops do production plating as a rule. They don't spend their time experimenting with different combinations of commodity chemicals; rather, the plating process suppliers do the research & development and market their processes to plating shop. I've heard about suppliers offering alternatives to hexavalent chromium; I know that the most popular is trivalent chromium, and that there are others, but I would have no clue how to formulate them, nor knowledge of their reflectivity, color, etc.

I would suggest searches on surfacequery.com, scholar.google.com, and patft.uspto.gov/netahtml/PTO/search-bool.html. Good luck.

Regards,

A. Hi again Ali. Glad that you seem to have found a solution. Depending on how high quality your chandeliers are, another alternative is rhodium plating. This is roughly as expensive as gold plating, but is a bright reflective finish that looks even brighter & better & more scintillating than chrome plating ... you've probably seen it on white gold engagement rings.

Regards,