How to Dress Natural Building Stones? [PDF]

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The naturally available stones from the quarry are irregular in shape and size. In order to bring them into the desired shape, size, and finish, they are dressed, and this process is called dressing. Dressing of natural building stones provides a good appearance and makes them useful for masonry works.

The stones can be dressed into various types, depending upon the size, shape, and finish desired for the masonry work.

The procedure of dressing natural building stone in different finishes is explained in this article.

1. Pitched Faced Dressing

1. The stone received from the quarry shall be dressed along all the edges of its face utilizing a mason’s hammer or club hammer and the pitching tool.
2. The edges of the pitched-faced dressed stone shall be level and in the same plane being perfectly square with the base of the stone. 
3. The superfluous natural stone on the face shall be allowed to remain there and left raised in the form of a natural rounded cobblestone.
4. The minimum width of pitched-faced dressing around the four edges of the face of the stone shall be 25 mm. 
5. The appearance of pitched face stone is, as shown in figure 2.

2. Hammer Dressing

1. The stone received from the quarry with sharp and irregular corners shall be chipped off by utilizing the flat face of a scabbling or spalling hammer.
2. A hammer-dressed stone shall not have sharp and irregular corners and shall have a comparatively even surface to fit well in masonry. 
3. The dressing on the face shall not be more than 40 mm on an exposed face.
4. The hammer-dressed stone is also known as quarry faced, hammer faced, and rustic faced. The appearance of a proper hammer dressed stone is as shown in figure 3.

3. Rock Facing Dressed

1. The rock facing dressed stone shall have a minimum of 25 mm wide fine chisel marks at the four edges, all the edges being on the same plane. 
2. These dressed stones are used in buildings as quoin stones in the corners of brick masonry or rubble masonry and in the plinth to give an appearance of strength and solidity. 
3. All the sharp and irregular corners of the stone shall be knocked off by using the flat face of a scabbling hammer. 
4. The superfluous stone along one edge AB (see figure 4) shall be knocked off with a drafting chisel and a hammer until it coincides with a straight edge throughout its whole length.  This is known as the chisel draft. 
5. Further chisel drafts shall now be made along BC, CD, and DA, so that the four corners are at the same level.
6. A part of the superfluous stone in the center, which is left, raised and rough to imitate a rock-like surface shall be removed with the pitching tool or the scabbling hammer. The appearance of rock-faced stone is as shown in figure 4.

4. Rough Tooling Dressed

1. Rough-tooled stones are used where fairly regular plane faces are required for masonry work.
2. A rough tooled surface shall have a series of bands, 4 to 5 cm wide, more or less parallel to tool marks all over the surface.
3. The edges and corners shall be rendered square and true.
4. The dressed stone may have depressions on the surface. 
5. The depth of the gap between the surface and a straight edge held against the surface shall not be more than 3 mm. 
6. The surface of the stone shall be dressed removing the top layer of about 0.3 cm thick using a plane chisel or a boaster and a mason’s or club hammer, by forming a series of 4 to 5 cm wide bands of more or less parallel tool marks which covers the whole surface. 
7. These marks can either be horizontal, vertical, or at an angle of 45⁰ as required, and in making them the boaster or chisel shall be moved in the direction of the band at each stroke (see figure 5).
8. The surface shall be tested with a mason’s square for the conformity of the above-given requirements.

5. Punched Dressing

1. A rough tooled surface is further dressed to show a series of parallel ridges.  Chisel marks shall be left all over the surface.
2. The depth of the between the surface and a straight edge held against the surface shall not exceed 3 mm. 
3. The depressions are formed on the rough surface of the stone in rough tooling with a punch chisel and a mason’s or club hammer at close intervals and to a depth of about another 3 mm to form a series of parallel ridges (see figure 6).
4. The stone shall be checked with a straight edge for the requirement given above.

6. Closed Picked Dressing

1. A punched dressed stone is further worked to obtain a finer surface, ridges, or chisel marks leftover being very tiny. 
2. The depth of the gap between the surface and a straight edge kept over the surface shall not exceed 1.5 mm.
3. It is dressed with a pointed chisel and mason or club hammer by forming small pits of about 3 mm depth to obtain a finer surface, the ridges, or chisel marks leftover being tiny.

7. Fine Tooling

1. A fine tooling stone is obtained by further dressing of closed, picked surface so that all the projections are removed, and a fairly smooth surface is obtained.
2. The surface shall have 3 to 4 lines per centimeter width depending on the degree of hardness of stone and degree of fineness required. 
3. Fine tooling dressed stone is very commonly adopted for ashlar work.
4. The stone received from the quarry shall be closed picked and then fine tooled with a serrated or claw chisel and a mason or club hammer. 
5. By this operation, all the projections caused in the earlier stages shall be removed and a fairly smooth surface obtained.

Finishing Procedure for all type of Dressed Stones

Once the dressing of the stone is completed as per the desired level and shape, it is further finished by following two procedures-

1. Dragging or Combing

The dressed stone is further worked by dragging the coarse drag backward and forwards until the tool marks are eliminated.  This may be followed by second drag and fine drag according to the degree of evenness required.

2. Polishing

1. The polishing of stones shall be done by rubbing them with a suitable abrasive, wetting the surface, where necessary, with water.
2. Alternatively, polishing of stones shall be done by holding them firmly on the top of the revolving table to which some abrasive material like sand or carborundum is fed. 
3. The final polishing shall be performed by a rubber or felt, using oxide of lime called by trade as ‘putty powder’ as a polishing medium.

FAQs on Dressing of Natural Stone

Read More:
1. Dressing of Stones with Different Finishes for Masonry Works
2. 10 Types of Stones Used for Building Constructions
3. 12 Commonly Used Building Stones – Their Properties and Uses