Dressing of Stones

The dressing of stone is defined as “The process of giving a proper size, shape and finish to the roughly broken stones as obtained from the quarry.” This process is done manually or mechanically. Stones obtained from the quarries are very rough and irregular in shape and quite bulky in size and weight. A dressed stone is fit for use in a particular situation in a building. A quarried stone has rough surfaces, which are dressed to obtain a definite and regular shape. Dressing of stones is done immediately after quarrying and before seasoning to achieve less weight for transportation. Dressing of stone provides pleasing appearance, proper bedding with good mortar joints, special shapes for arches, copings, pillars etc. The various types of dressed stones are shown in Fig.1.

Fig. 1 Dressed Stone Surfaces

With respect to the place of work, dressing can be divided into two types namely

1. Quarry dressing
2. Site dressing

Advantages of dressing, if it is carried out at quarry site.

1. At quarry site, it is possible to get chap labour for the process of dressing of stones.
2. It is possible to sort out stones for different works, if quarry dressing is practiced.
3. The irregular and rough portions of the stones are removed which decrease the weight of stones and it also facilitates easy transportation of the stones.
4. The stones when quarried freshly contain quarry sap and hence they are comparatively soft and can be easily dressed.

Various objectives of dressing are given below.

• To reduce the size of the big blocks of stones so that they are converted to easily liftable pieces. This reduction in size is generally carried out at the quarry itself because that saves a lot of transportation cost.
• To give a proper shape to the stone. It is known that stones can be used at different places in the building, e.g. in foundations, in walls, in arches or for flooring, each situation will require a proper shape. This can be given at the quarry and also at the site of construction.
• To obtain an appealing finish. In a residential building, stones are used not only because of their extra strength, hardness and durability but also because of their aesthetic value.

Methods / Types of Dressing of Stones

Dressing of stone can be done both manually as well as mechanically. Manually, skilled stone smiths can work wonders on the suitable type of stones with chisels and hammers and abrasives. Mechanically, machines can cut the stone to any desired size and shape. Their surfaces can be made extra smooth by polishing through machines. There are some traditional types of dressing of stones which are quite popular even at present. They are described below.

1) Pitched Dressing

In Pitched dressing, only the edges of a stone block are made level with the help of a hammer. The superfluous mass on the face is generally left intact.

2) Hammer Dressing

It is that type of dressing in which large raised portions of the stones are broken off, and the stone is shaped somewhat flat but rough due to hammer marks. These stone blocks are squared, and the bed and vertical sides are dressed to a distance of 8 to 10 cm from the face. This is done to enable the stone to have proper joints. This work is done by the use of Waller’s hammer. The obtained stones are termed as hammer faced, quarry-faced or rustic faced.

3) Chisel Drafting

In this method, drafts or grooves are made with the help of a chisel at all the four edges. Any superfluous stone from the center is then removed. Chisel drafted stones are specially used in plinths and corners of the buildings.

4) Rough Tooling

The edges are first squared by using a chisel and hammer. Then a series of grooves of variable width are developed over the surface of the stone.

5) Punched Dressing

In this method of dressing of stone, about 1 cm vertical or horizontal grooves are sunk with a chisel having it’s shaped as a hollow semicircle. The sides of the rock are kept chamfered or sunk. It is done on the stones that have already been rough tooled. With the help of Chisels, a series of parallel ridges are developed on the stone surface. It is also called furrowed finish.

6) Close Picked and Fine Tooling

This is an extreme type of dressing of stone in which almost every projection is removed from all the sides of the stone. Its surface is given a fine texture and appealing look.

7) Boasted or Droved Finish

It is a very common type of dressing of stone, in which the surface of the stone is covered with parallel marks that may run in any direction. A boaster which is actually a wide edged chisel is used for this purpose. These marks may be horizontal or at any angle. The chisel marks are not continuous across the whole width of the stone.

8) Scabbling

Irregular edges of the stones are broken off and the stone is shaped. This work is generally done in a quarry and the edges are broken with a scabbling hammer.

9) Reticulated Finish

In this type of dressing of stones, irregularly shaped sinking are made within the central portion of the stones having a 2 cm wide margin on its sides. These sinking are about 6 mm deep. The margin around the sinking is of constant width. The sunk surfaces may have punched marks to give a better appearance.

10) Vermiculated Finish

This type of dressing of stone is the same as the reticulated finish except that they are more curved and give a worm eaten type appearance. It is not very common as they need a lot of labour for construction.

11) Combed or Dragged Finish

This type of finish is done on soft stones. A comb is driven over the surface of this stone to remove it all elevating portions.

12) Picked Dressing

This type of Dressing of stones is obtained by finishing the stone with a point and the depression is smaller than the above type.

13) Moulded Finish

Moulding is done to improve the appearance of stones. These are either handmade or machine made.

14) Rubbed Finish

In this method of dressing of stone, the surfaces of stones are rubbed to get a smoother finish. One piece of stone is rubbed against the other. Water and sand are added to aid the operation. It can also be rubbed by hand or machines.

15) Polished Surfaces

Stones which can take polish, e.g., granites, marbles, limestone etc. are first rubbed and then polished by using rubber, pad, sand, water and putty powder. However, a machine can also be used for polishing.

16) Sand Blasting

This method of dressing of stone is done to imprint letterings and designs on the surface of granite. The polished surface is coated with a molten rubber like compound which solidifies on cooling. The desired design is cut on this coating with a sharp tool thereby exposing the stone surface which is to be cut. A blast of sand is then blown with compressed air, the part which is exposed is cut to the depth needed.

Stone Dressing Tools

The dressing tools are shown in Fig. 2. They are wedge, pitching tool, boaster, scabbing hammer, mash hammer, separated pick, punch, scabbing pick, crow bar, axe punch, dressing knife and splitting chisel. Some other tools like mason’s hammer, spacing hammer, club hammer, soft stone chisel, claw chisel, punching chisel, point chisel, drafting chisel etc. are also used.

Fig. 2 Tools for Cutting and Dressing Stones