That's why good table knives are in danger in the dishwasher
22.12.2022
Translation: machine translated
It's convenient to clean your cutlery in the dishwasher. But during a visit to manufacturer Sola in Emmenbrücke, I learn that this is almost sacrilegious. A great deal of expertise is required in the production of a knife.
The question of how to fill a dishwasher "correctly" has put many a marriage in danger. Fortunately not mine. Although, against my wife's advice, at some point I also started putting the knives of our cutlery into the machine instead of washing them by hand. "They're dishwasher safe, aren't they?" I explained confidently. But now the knives have little black spots and no longer shine. What happened?
Source: Martin Jungfer
That's what I want to find out - and I'm learning a lot about cutlery in my search for answers.
First of all, regarding our stained knives, I write an email with photos of the damage to Sola, the Swiss manufacturer of our cutlery. I get an extremely friendly but also very clear answer: "These stains were caused in the dishwasher". My wife was right after all.
After all: I'm not the only one who has a problem with our cutlery.
After all: I get a replacement from Sola for the knives I ruined through my own fault.
Knives are different from forks and spoons
So the acute problem is solved. I save myself buying a new complete cutlery set - and save resources. After all, apart from the knives, all the other pieces are still in perfect condition. And for the future, I know how to protect my knives from permanent damage at an early stage.
There are still questions. One is: Why do only the knives get damaged in the dishwasher? This is because knives are not made of the same stainless steel as spoons and forks. There are mainly two manufacturing processes for table knives:
Hollow handle knives: knives made of two parts
These consist of a forged blade made of special knife steel and the handle, the so-called hilt. It is therefore a composite eating tool. The blades have a high elasticity and stay sharp longer. Blades of hollow-handled knives can be resharpened, they are thinner and therefore cut better. Because they consist of two parts, the production of hollow-handled knives is more complex and expensive.
Monobloc knives
These knives are stamped from a single piece of chrome steel, hardened and finally ground. This is comparatively cheap to manufacture. The blade of a monobloc knife cannot be formed as thinly because of the material, so it cuts worse.
The steel used for monobloc knives is usually an alloy of chrome (18 percent) and steel (82 percent). In product descriptions, this alloy appears as "18/10 stainless steel" or "18/10 chrome steel". The blade steel for hollow-handled knives, on the other hand, is often specially hardened knife steel, often an alloy without nickel. For example, "18/0 stainless steel". The 0 then stands for the lack of nickel.
Source: Thomas Kunz
Cutlery manufacturers who rely on monobloc knives take advantage of the fact that the chrome steel used is less sensitive. Chrome-nickel steel is usually used for the other cutlery parts. Here, ten percent nickel is added to the alloy in addition to the chromium. This cannot be hardened, so it can only be used for non-cutting parts such as forks and spoons. CNS 18/10, as the alloy is called, is not magnetic and does not rust. Sometimes molybdenum is also added to the alloy, which gives rust even less of a chance.
Almost all cutlery sets that you pick up for little money at the furniture store are those with monobloc knives. This means you actually get a largely rust-free and easy-to-clean set. On the other hand, they become blunt more quickly and cannot be resharpened.
Combining the best of both knife worlds
In the catering industry in particular, knives are used frequently and must cut well for a long time so that guests can cut cutlets and potatoes into bite-sized pieces. Less expensive monobloc knives would have to be replaced very often, but hollow-handled knives are expensive and the blade is more sensitive. Ideally, the blade of a monobloc knife would stay sharp longer. Or the blade of a hollow-handled knife would be less sensitive.
The company WMF, based in the Swabian town of Geislingen, relies on "Cromargan Protect", which is initially not much more than a marketing neologism. I want to know what's behind it and ask Tobias Good, the Key Account Manager for Switzerland. He explains to me the special finishing process that is supposed to protect a cutlery set with monobloc knives better from scratches and rust - although it does not use nickel. To become Cromargan Protect cutlery, the knives, forks and spoons have to undergo heat of over 1000 degrees in a vacuum oven. Nitrogen is injected into their surface. During the subsequent rapid cooling, a hard edge layer is formed. Tobias Good goes on to say that this is a "unique innovation" and a clear "differentiation from all other cutlery manufacturers".
However, WMF's range includes sets with inset blades for the table knives. These blades are then also made of special knife steel that is susceptible to rust. According to WMF, the blades cannot be effectively protected with "Cromargan Protect".
Do other cutlery manufacturers have other ideas? I contact Sola again and am referred to Thomas Gerritsen. He is CEO and fifth-generation owner of Sola, based in Emmenbrücke near Lucerne. On the phone he doesn't want to tell me the secrets of Sola knives. He said I should just come by and he would show me everything. Deal.
Source: Thomas Kunz
A few days later, the time has come. I get a crash course in knife production. When it comes to the basic material, the harder the steel, the drier it is and the easier it breaks. For Thomas Gerritsen, a knife made of one piece, i.e. the monobloc knife, is therefore "always a compromise". It has to be hard when it is struck against each other, but also not too hard so that the blade can be sharpened.
The better knives, therefore, are clearly the hollow-handled knives. At Sola they use chrome-nickel steel for the handle and special knife steel for the cutting edge, which also gets a special serrated edge. The two parts are welded together and the seams are polished smooth. All in all, it takes a few dozen steps, most of them by hand, until a hollow-handled knife is finished. Above all, forging the blade from a rectangular steel blank is time-consuming. It can be hot or cold forged. In both processes, the piece of steel becomes thinner and longer. When it has the desired length, the blade is cut out. At the bottom of the blade remains the so-called tang, a kind of pin with which the blade is later inserted into the hilt.
Source: Thomas Kunz
Depending on the design of the cutlery, the seams can either be made almost completely invisible by grinding them at the end or they can remain clearly visible. For example, so that guests can see your good taste and expertise with knives right away.
Source: Thomas Kunz
Gerritsen is a fan of hollow-handled knives because they give him more design options. They are also better balanced because different weights can be placed in the hollow handle as needed. Quartz sand is filled into the hollow handle, which consists of two shells, the hilt. When you hold the knife in your hand while eating, it feels valuable and well balanced, if knife experts like Thomas have done a good job.
Our knives at home are also hollow-handled knives, that's what I learned. Simply those where the transition between blade and handle is not immediately recognisable due to grinding and polishing. But they are knives with a somewhat more sensitive blade - which I will rinse by hand in future.
Martin Jungfer
Head of Content
Martin.Jungfer@digitecgalaxus.chJournalist since 1997. Stopovers in Franconia (or the Franken region), Lake Constance, Obwalden, Nidwalden and Zurich. Father since 2014. Expert in editorial organisation and motivation. Focus on sustainability, home office tools, beautiful things for the home, creative toys and sports equipment.