According to T 21/81 (OJ 1983, 15), it had to be regarded as forming part of his normal activities for a skilled person to select, from the materials known to him as suitable for a certain purpose, the one which was the most appropriate. The skilled person should therefore be at liberty, within the constraints of standard technical progress, to use alternative means known by him to have the same effect (T 324/94). In T 410/92 the board also held that using higher-quality materials in the design of single-phase synchronous motors with a double-pole permanent-magnet rotor was obvious. The appellants had argued that the skilled person using the superior materials available to him would be confronted with baffling starting problems. The board however concluded that the skilled person's encountering known problems when using newly developed materials would not deter him from using them in order to achieve specific, desired improvements, particularly since the means of overcoming such problems could be derived from the prior art.
The Headnote in T 192/82 (OJ 1984, 415) read as follows: If an article is known as a combination or mixture of components fulfilling known functions, the generation and application of an improved novel component for the same purpose may be patentable as such and also as an improved article incorporating the same. If the component in question forms, on the other hand, part of the state of the art together with its relevant properties, the incorporation thereof in the same article will be obvious in view of its predictable beneficial effect ("analogous substitution").
In this connection the board also established in T 130/89 (OJ 1991, 514) that the use of a known material on the basis of its known properties and in a known manner to obtain a known effect in a new combination was not normally inventive ("similar use"). Exceptions to this principle might be allowed in special cases, e.g. where a selection brought unexpected advantages, a known prejudice was overcome or unforeseen difficulties were encountered, such as the need to alter another component (see also T 1216/05, T 330/07, T 422/09).
Following these decisions, the board summarised as follows in T 213/87; in the absence of any unexpected effect, the mere substitution of an element by another known for its relevant properties to provide that known effect could not be regarded as patentable.