Materials.

Benjamin Thompson noted at the start of the 19th century that kitchen utensils were commonly made of copper, with various efforts made to prevent the copper from reacting with food (particularly its acidic contents) at the temperatures used for cooking, including tinning, enamelling, and varnishing. He observed that iron had been used as a substitute, and that some utensils were made of earthenware.[2] By the turn of the 20th century, Maria Parloa noted that kitchen utensils were made of (tinned or enamelled) iron and steel, copper, nickel, silver, tin, clay, earthenware, and aluminium.[3] The latter, aluminium, became a popular material for kitchen utensils in the 20th century.Copper
Copper has good thermal conductivity and copper utensils are both durable and attractive in appearance. However, they are also comparatively heavier than utensils made of other materials, require scrupulous cleaning to remove poisonous tarnish compounds, and are not suitable for acidic foods.[5] Copper pots are lined with tin to prevent discoloration or altering the taste of food. The tin lining must be periodically restored, and protected from overheating.
Iron
See also: Cast-iron cookware
Iron is more prone to rusting than (tinned) copper. Cast iron kitchen utensils are less prone to rust by avoiding abrasive scouring and extended soaking in water in order to build up its layer of seasoning.[6] For some iron kitchen utensils, water is a particular problem, since it is very difficult to dry them fully. In particular, iron egg-beaters or ice cream freezers are tricky to dry, and the consequent rust if left wet will roughen them and possibly clog them completely. When storing iron utensils for long periods, van Rensselaer recommended coating them in non-salted (since salt is also an ionic compound) fat or paraffin.[7]
Iron utensils have little problem with high cooking temperatures, are simple to clean as they become smooth with long use, are durable and comparatively strong (i.e. not as prone to breaking as, say, earthenware), and hold heat well. However, as noted, they rust comparatively easily.[7]
Stainless steel
Stainless steel finds many applications in the manufacture of kitchen utensils. Stainless steel is considerably less likely to rust in contact with water or food products, and so reduces the effort required to maintain utensils in clean useful condition. Cutting tools made with stainless steel maintain a usable edge while not presenting the risk of rust found with iron or other types of steel.
Earthenware and enamelware
Main article: Clay pot cooking
Earthenware utensils suffer from brittleness when subjected to rapid large changes in temperature, as commonly occur in cooking, and the glazing of earthenware often contains lead, which is poisonous. Thompson noted that as a consequence of this the use of such glazed earthenware was prohibited by law in some countries from use in cooking, or even from use for storing acidic foods.[8] Van Rensselaer proposed in 1919 that one test for lead content in earthenware was to let a beaten egg stand in the utensil for a few minutes and watch to see whether it became discoloured, which is a sign that lead might be present.[9]
In addition to their problems with thermal shock, enamelware utensils require careful handling, as careful as for glassware, because they are prone to chipping. But enamel utensils are not affected by acidic foods, are durable, and are easily cleaned. However, they cannot be used with strong alkalis.[9]
Earthenware, porcelain, and pottery utensils can be used for both cooking and serving food, and so thereby save on washing-up of two separate sets of utensils. They are durable, and (van Rensselaer notes) “excellent for slow, even cooking in even heat, such as slow baking”. However, they are comparatively unsuitable for cooking using a direct heat, such as a cooking over a flame.[10]
Aluminium
James Frank Breazeale in 1918 opined that aluminium “is without doubt the best material for kitchen utensils”, noting that it is “as far superior to enamelled ware as enamelled ware is to the old-time iron or tin”. He qualified his recommendation for replacing worn-out tin or enamelled utensils with aluminium ones by noting that “old-fashioned black iron frying pans and muffin rings, polished on the inside or worn smooth by long usage, are, however, superior to aluminium ones”.[11]
Aluminium’s advantages over other materials for kitchen utensils is its good thermal conductivity (which is approximately an order of magnitude greater than that of steel), the fact that it is largely non-reactive with foodstuffs at low and high temperatures, its low toxicity, and the fact that its corrosion products are white and so (unlike the dark corrosion products of, say, iron) do not discolour food that they happen to be mixed into during cooking.[4] However, its disadvantages are that it is easily discoloured, can be dissolved by acidic foods (to a comparatively small extent), and reacts to alkaline soaps if they are used for cleaning a utensil.[12]
A museum mannequin standing in front of a table set with various kitchen utensils, with more kitchen utensils hanging from the wall behind
An exhibit of Israeli Defence Forces kitchen utensils at the Batey ha-Osef Museum in Tel Aviv
In the European Union, the construction of kitchen utensils made of aluminium is determined by two European standards: EN 601 (Aluminium and aluminium alloys — Castings — Chemical composition of castings for use in contact with foodstuffs) and EN 602 (Aluminium and aluminium alloys — Wrought products — Chemical composition of semi-finished products used for the fabrication of articles for use in contact with foodstuffs).
Plastics
Biodegradable plastic utensils made from bioplastic
Plastics can be readily formed by molding into a variety of shapes useful for kitchen utensils. Transparent plastic measuring cups allow ingredient levels to be easily visible, and are lighter and less fragile than glass measuring cups. Plastic handles added to utensils improve comfort and grip. While many plastics deform or decompose if heated, a few silicone products can be used in boiling water or in an oven for food preparation. Non-stick plastic coatings can be applied to frying pans; newer coatings avoid the issues with decomposition of plastics under strong heating.
Glass
Heat-resistant glass utensils can be used for baking or other cooking. Glass does not conduct heat as well as metal, and has the drawback of breaking easily if dropped. Transparent glass measuring cups allow ready measurement of liquid and dry ingredients.