The best notion of the process of warping may be gained by sailing up the Trent from the Humber to Gainsborough.
It is important that the thermal expansion of the two materials which are thus incorporated should be nearly alike, as otherwise warping of the finished sheet is liable to result.
The chief processes for the improvement of soils which may be discussed here are: liming, claying and marling, warping, paring and burning, and green manuring.
The amount of deposit laid over the land reaches a thickness of two or three feet in one season of warping, which is usually practised between March and October, advantage being taken of the spring tides during these months.
In this way the danger of warping is averted, and exudations from the wooden surface are prevented from reaching the overlaid coats of lacquer.