The possible use of adhesives in a new design should always be considered because of the economic and technical benefits thatthey can confer. Light, stiff and economic structures, free of the blemishes caused by conventional assembly methods, can be fabricated from a variety of materials in combinations which would otherwise be hard to achieve. Similarly, mechanisms may be built up using bonding techniques which are free of the costs and stresses implicit in press fitting. Adhesives are not a panacea, but they do have a great deal to offer as is shown by the vital role they play in modern production engineering. Yet, despite this, they are not generally regarded with enthusiasm by engineers and designers. The reason for this is not hard to find. There are so many adhesives with such diverse properties that, in the absence of a unifying science which can explain not only why adhesives stick but why they behave as they do, a very strong incentive is required to guarantee perseverance. In addition, although the polymeric structures of adhesives are well understood, this knowledge is usually of little help to the engineer who is used to dealing in precise terms and may be readily put off by a subject which he tends to regard as being arcane and wooly.