For hand mixing, a water tight platform or shallow box should be used, of such a size that the given batch will not cover the bottom more than four inches deep.
If the sand is measured, a bottomless box, provided with two handles at each end, will be found more convenient than the bottomless barrel which is often employed for this purpose. When the sand is delivered on the mixing platform in barrows, the latter may be fitted with rectangular boxes to avoid re-measuring. A two-wheel cart, the box of which may be inverted to discharge the contents on the mixing platform, will also be found very serviceable when the runway is suited to such a vehicle.
The proper amount of sand is evenly spread on the platform, the cement is then dumped on top of the sand and spread out over it to an even thickness. With either hoes or shovels the dry materials are then thoroughly mixed, until, when a small amount is taken in the hand, it will appear of uniform color throughout. From two to five turnings of the materials, according to the expertness of the workmen, will be required to produce this result. The dry mixture is then drawn to the edges of the platform to form a ring, and the requisite amount of water is added at one time in the center. The mixture is then gradually incorporated with the water, and the mass is thoroughly worked until plastic and homogeneous. Should it be found that too little water has been used, a small amount may be added from a sprinkling pot or rose nozzle, but the mass should always be worked over again after such addition. Four shovels may be used at one platform, but if the mixing is done by hoes, not more than two can be used to advantage with a batch of ordinary size.
Some engineers prefer one method and some the other, but in whatever manner done, the mixing should not be stinted. From two to four turnings of the mass are usually considered sufficient, but as a general rule it will be found that further mixing, beyond that required to just give the mass a uniform appearance, will be amply repaid in the strength of the resulting mortar. (See Art. 47).