A flat lapped joint, partly burnt, is shown by [Fig. 74]. In burning this joint, the stick of lead is only required to fill up any irregularities in the burning, and is not required to form the seam in the same way as it is in a butted joint, because in lapped burning the overcloak is burnt down on to the undercloak, as shown in [Fig. 75]. In horizontal and vertical burning, lapped joints only should be used.
[Fig. 75] shows a specimen of horizontal or side burning, and [Fig. 76] one of vertical or upright burning. In burning both of these, the stick of lead is not required at all, the overcloak being in each case burnt down on to the undercloak. Care must be taken that both the overcloak and undercloak of a lapped joint are well shaved.
Fig. 73.--Butted Seam Partly Burnt
Fig. 75.--Horizontal or Side Burning
Fig. 74.--Lapped Seam Partly Burnt
Fig. 76.--Vertical or Upright Burning