With the stuff to the chrome

Auto Motor Klassiek » Practice and technology » With the stuff to the chrome
Purchasing classics there

chrome guzziThe glossy finish of many restorations is the chrome work.
Rusty chrome usually manifests itself as a large number of brown dots in the chrome work. It is not the chrome that rusts but the steel under the (porous) chrome layer. Rust expands and then breaks through the chrome layer. We're going to talk about chrome. Also because a few things went from the Editorial Guzzi to the galvanotechnical company Latour in Nijmegen.

Because chrome is not forever. Certainly not Italian chrome….

chrome guzziWe chose Latour instead of one of the former Balkan countries because of the environmentally friendly way of chrome-plating in Nijmegen: with Chromium 3 instead of the carcinogenic Chromium 6. Moreover, we have the experience that there is much less chance of recovery at chrome-plating companies in the Czech Republic and Poland when things get lost or if the quality turns out to be below par.

Chrome plating is a galvanic process. And galvanizing is a method that uses electricity to cover an object with a layer of metal. By means of galvanizing, for example, a steel plate can be provided with a layer of zinc, nickel or chromium to make it more resistant to corrosion or to make it shine more beautifully.

The term galvanic technology or galvano is used within the industry. All electrochemical coating techniques are referred to by these terms. The still existing company WMF (Coffee machines and cutlery) started in 1838 with galvanoplastic on an industrial scale.
In 1854, Robert Wilhelm Bunsen manages to be the first to knock down chrome. Siemens is developing the dynamo machine in 1867, and then galvanic technology is gaining momentum.

Nickel is deposited for the first time in 1900, and chromium is widely used commercially from 1924. The development of these brighteners takes place between the two world wars, as a result of which labor-intensive polishing is greatly reduced. Chemical nickel is marketed shortly after WWII.

Chrome
Chromium is the best known of the precipitated metals. It is used in the sanitary market, the automotive industry, bicycles, motorbikes and so on. It is widely used to give metal (or even some twenty or even plastic) a better appearance. Chrome itself has no high gloss properties, the shine comes from the underlying nickel. Chrome can be polished. If the chrome layer is applied too thickly on the shiny nickel, a mouse-gray layer is created. A chrome layer of approx. 0,5 μm is sufficient to achieve a beautiful appearance. Chromium baths are among the simplest in terms of composition, they consist largely of chromic acid, and additions of sulfuric acid (catalyst in the process) are added. As secondary catalysts, fluoride compounds or organic compounds can be added. The chromium bath removes the chromium from the chromic acid present, the anodes are leaded, these only provide the required electrons.

There is a difference between decorative and hard chrome, this mainly concerns the layer thickness that is deposited. Chemically, both baths are almost identical. Hard chrome layers can be separated up to 1 mm, as a rule 20-100 μm is deposited. It is applied because of its high hardness and wear resistance. The disadvantage, however, is that the layer is porous and that in this way especially Cl ions can attack the base material through the layer. For these applications it is therefore better to apply a Nickel layer under the Chrome layer. The hardness of the chromium can vary from 850-1200 HV (Vickers hardness) depending on the chosen process (read: secondary catalyst). Areas of application are engine technology, hydraulics, mold construction etc.

Nowadays, trivalent chromium baths are also used, in connection with the ever-increasing debate about carcinogenic chromium 6 +. Latour works exclusively with chrome 3.
Some chromium alloy baths are also known, but they have little commercial significance. It concerns chromium / molybdenum (better dry-running properties and increased resistance to chlorides) and chromium / tungsten (better anti-corrosion properties). There is also a black chrome bath. The addition of salts results in a black, somewhat powdery chromium layer that is often put in a special oil and that can have a deep black color. This approach is fairly well-known from hand-arm manufacture.

The baths used for electroplating are a major burden on the environment and are therefore nowadays subject to very strict rules.

Only about forty years ago there were chrome fittings in the oldest neighborhoods of the inner cities. The buildings were recognizable from the outside because the acid fumes had eaten through the single-walled walls. On the inside, the acid had made thin, white, fungal growths grow out of the walls. The open acid baths bubbled and vaporized. The extraction was usually provided through cracking windows and the lungs of the rapidly changing workforce. The lungs of the polishers were the first to turn. Because with those heroes standing bent all day, sourdoughs were given a warm welcome in the lungs upholstered with flaky polishing dust. The floors usually consisted of vowels that were acidified to the last pore. Tens of years later, the land beneath the buildings made the soil remediators rich in snow.

Chrome plating again is a process that consists of multiple operations.
The old layers (lacquer, nickel and chrome) must first be removed.
ALL rust must then be completely removed.
The first two steps are done with the help of corrosive baths. Nowadays, a very layer of ping-pong balls often float on these baths to reduce their evaporation. Of course the ventilation, the extraction and the personal respiratory protection are also a thousand times better than in 1961.

The part is then ground, brushed and polished. The people who do this are professionals in their field and their chances of survival are now at a normal level because they work under high volume hoods and at least wear 'faces'. This machining phase can cause problems if the part is seriously affected by rust. Grinding can make the material thickness too small or cause unevenness in the surface. And those irregularities are deadly for the end result. The possibility of 'coppering' to get back to thickness exists and makes the job considerably more expensive.

NOTE: Perfectionists know preprocessing is the most important. Among those same perfectionists there are a few who swear never to have polishing done at the chrome plated because polishing is a completely different craft. But that they are the hard core fundamentalists among us who say that ...

We do not want to be more Roman than the Pope, but always discuss the polishing with the chromator.

In the past, the parts were always first coppered. Later, in the sixties, the Japanese thought that all surface treatments could also be done on degreased plate. The generally accepted golden mean is that nickel plating is used for chroming. But first copper is best. As a result, an even better corrosion resistance is achieved. The product must then be polished again after copper plating. This makes the operation extra laborious and therefore more expensive.

You can compare the copper layer with the primer layer of a lacquer system. People who have their chrome work done cleverly in the former Eastern Bloc countries can be cheap. There are quite a few reliable addresses for adventurous spirits there. But from an environmental perspective, think of the Rotterdam city center in 1961. And who wants that on his conscience now? And prefer not to think about local working conditions or the environment ..

Back to the present. The chrome-plated product is always nickel-plated first. You can compare the nickel layer with the color lacquer of a lacquer system. This is the thickest layer of the whole.
The chrome layer is applied after nickel plating. The chrome layer gives the high gloss. This is comparable to the clear varnish that is often used as a final finish for a varnish system.
You now understand that this entire process is quite labor intensive and that makes re-chrome plating seriously costly. Sometimes so much that it is cheaper to buy 'new reference'. Despite the fact that the quality is not always that good. Especially when it comes from China. .

For people who do not go for showroom sunshine, it can be an option to have the parts 'technically' chromed. That saves a number of processing steps when polishing, it glows less. But that may be desirable because the parts do not look 'too new' after mounting on a patina vehicle. For the Guzzi we opted for that approach.

And how does that end with the Guzzi stuff? We know that next week.

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