72 Condition and Maintenance of Hand Power Tools, Knives, and Saws
Learning Objectives
- Examine the condition of power tools, knives, and saws to identify faults
- Explain the proper maintenance of knives and saws
Condition of Knives
Blunt or dull knives are a hazard because they require additional force to cut. With additional force, it is easy to lose control of the blade and have it move in unpredictable ways. An easy way to test the condition of a knife is to cut a piece of paper from the heel of the knife to the tip.
- No pressure should be necessary to cut the paper
- There should be no catching or bending/ wrinkling of the paper
- The cut edge of the paper should be clean (not ragged or rough)
It is not necessary to watch it all, but the following video gives a good idea of what a truly sharp knife can do! (Notice how little force is required to use a sharp knife.)
Maintenance of Knives
An important part of maintaining a knife is the cleaning and sanitizing. Cleaning removes particles that can lead to cross-contamination of food and the growth of microbial pathogens. Sanitizing kills microbial pathogens and can be done by resting the knife in a tank of sanitizing solution for that purpose or storing the knife in a box that exposes it to bacteria-killing ultraviolet (U.V.) light.
In general, do not:
- Soak the entire knife (including the handle) in a sanitizing solution or dishwater.
- Sanitize the blade before cleaning it.
- Put the knife in the dishwasher (that will dull the blade)
- Store in a drawer with other cutlery
- Cut on stainless steel
Knife Sharpening
Whetstone
A whetstone is an abrasive surface that will grind or shape the blade of a knife. There are several “grits” available (meaning the coarseness off the surface of the whetstone.) The higher the grit number, the smoother the surface of the stone. Grit numbers can go into the thousands, but 1000 or on occasion 3000 is the finest grit commonly used. The finer the grit, the smoother the surface, and the sharper the edge can be achieved on the blade.
The finest grits merely polish the blade, they do not grind the metal. On the other hand, lower (coarser) grits can be used to grind off metal from the blade. This is useful in correcting extreme dullness, making a thinner cutting edge, or in some cases, removing small gouges and nicks.
The advantages of using a whetstone are that it is possible to achieve a long-lasting extremely sharp edge. However, this takes time and considerable skill.
Steel
A sharpening steel is used for quick maintenance of the blade, not grinding or correcting extreme dullness. There are several types of steel:
- Hardened steel- tiny grooves and ridges in the metal form the sharpening surface.
- Ceramic- tiny pores in the ceramic form the cutting surface.
- Diamond impregnated- near microscopic diamonds form the cutting surface.
Steels are used often (usually before or after) each cutting task. The edge they create is not long-lasting. Diamond-impregnated steels produce a slightly “toothier” edge than ceramic. This can be useful when cutting soft fruits and vegetables such as tomatoes.
Steels are quick and relatively easy to use, however, they do not correct extreme dullness, and the edge they produce is quite fragile.
Pull Through
A pull-through knife sharpener has gritty wheels that cross at an angle. The blade is drawn from heel to tip through the sharpener without applying pressure. These sharpeners are easy to use in that they take the guesswork out of the angle to grind the blade at. Like the electric sharpener, the angle is predefined. This does not work well for all knives: for example, Japanese knives are generally sharpened at a different angle than European knives.
Electric
An electric knife sharpener is similar to a pull-through in operation, however, it has grinding surfaces that rotate powered by an electric motor. This is an easy and fast way of sharpening knives. However, more material is lost (from the blade) than in other methods. As a result, the life of the knife is reduced.
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References
Editors. (2020, July 31). Knife Maintenance, Scales, manual slicers. Foodservice Equipment Reports, Articles & News | FER Magazine. Retrieved October 3, 2022, from https://www.fermag.com/articles/8787-knife-maintenance-scales-manual-slicers/#:~:text=Clean%20knives%20every%20time%20you,an%20additional%20level%20of%20cleanliness.
Knives and Tools, Staff Writer. (2018, March 22). Knife sharpening? we know how to sharpen your knife! Retrieved October 3, 2022, from https://www.knivesandtools.com/en/ct/knife-sharpening.htm