A security glass which possesses substantial resistance to penetration by impact by a heavy implement and which exhibits only a small amount of spall formation is a glass flexible bonding material, e.g. polyvinylbutyral (4), laminate in which the layer of flexible bonding material positioned other than at the forwardmost flexible bonding material layer position possesses increased thickness. The rearmost glass layer (7) is generally relatively thin and is preferably chemically toughened.