The screened barley is first steeped in water for a period which varies from two to four days, according to the nature of the barley and the temperature of the water. During this steeping it absorbs about one-half of its weight of water, and the grains become softened. Generally the water is drained off and replaced two or three times during the steeping, and for distillery malts it is a common practice to add calcium bisulphite or other antiseptic to prevent the development of harmful micro-organisms. For brewery malts there is less necessity to use antiseptics, because, apart from any effect which the subsequent kilning may have upon moulds and bacteria, these organisms are destroyed later on, when the wort is boiled and hopped; whereas neither boiling nor hopping is required by distillers' worts.

The steeped barley is next "couched," that is, spread out in a frame, or in a levelled heap a foot or more in depth upon the malt-house floor Here it begins to germinate. It absorbs oxygen and gives off carbon dioxide; the temperature commences to rise; and the surface of the corns shows an exudation of moisture ("sweating"). The grain is turned over now and then to aerate it and to equalise the temperature; and presently, as the growth of the embryo proceeds, a small, white rootlet appears at the end of the corn ("chitting"). When the temperature reaches 15° to 17° the couch or heap is broken down and spread into a thinner layer, varying in depth according to the season of the year ("flooring"). Whilst the grain continues to germinate it is well turned over two or three times a day; and when the growth has proceeded far enough the heap is spread more thinly, to allow of the grain gradually drying or "withering." Should the drying be too rapid, sprinkling with water is resorted to as a corrective. The necessity for this is shown by the rootlets becoming flaccid before sufficient growth has been obtained; and the amount of growth is judged by the distance to which the "acrospire" or "plumule" - the leaflet part of the young plant - has pushed its way under the husk from the base towards the apex of the corn. The temperature is not allowed to rise above 15.5°. When the process of withering is complete, the product, now known as " green " malt, is removed to the drying-kiln, unless it is to be used in the green state. Here it is gradually dried more completely, first at a low temperature (27 to 38°), and exposed to a current of air. The temperature is then slowly raised until the required degree is reached at which the malt is to be finished: this may vary from about 60° to 88° or even 110°, according to the kind of kiln used and the variety of malt required. This operation of kiln-drying usually occupies three or four days.

The length of time during which germination is allowed to proceed depends upon the purpose for which the malt is required. Malts intended for brewing are left on the "floor" for about seven to ten days ("short" malt). Malts for distillery and vinegar-making purposes are allowed to germinate much longer - about twenty days - in order to produce more diastase ("long" malt).

In "pneumatic" malting, the essential feature is a systematic aeration of the malt during the germinating stage by means of a current of air which, passing through a spray of water, warm or cold as desired, can be regulated as regards its moisture and temperature. The steeped grain is contained in revolving cylinders through which the air-current is led: this does away with the necessity for hand-labour in "turning" the grain, and saves much floor-space. The plentiful supply of fresh air, itself more or less purified by the washing it has received, keeps the malt free from moulds.

A. R. Ling1 has shown that when green malt is kept for some hours at a stage where it still contains from 10 to 15 per cent, of moisture, combination occurs between the amino-compounds and the carbohydrates containing free carbonyl groups; and when the products are heated in the final stages of kilning they are decomposed, giving rise to colouring and flavouring matters.