The cut of Alabaster
The work carried out at the sawmill can be described as follows:
• Peeling with manual tools, like hammers, mallets or spikes. The useful fragments are classified in terms of size and quality for subsequent operations.
• Sawing, with circular saws. Slabs or slices with specific thicknesses or types of surface can be obtained depending on the dimensions of the boulders and the requirements set by the final recipient.
• “Atochado”. Once the slices have been produced, “tochos” can be extracted, which are alabaster stone cylinders of different diameter and length depending on the thickness of the slice. The tool used in this process is the “tochadora”, a fixed drill with vertical movement through zip. The core drills are interchangeable and they come in a range of diameters. The “tochos” are eventually used for lathe carving.
• Veenering. From these slices, and through more precise sawing, plates of different sizes whose thickness ranges from 1 to 3 cm can be obtained.
• Sanding. The work piece is polished with steel wool in order to obtain a homogeneous texture that may remove the marks of cutting or turning.
• Colouring. Although the alabaster variety provides certain hues, some features of the stone can be highlighted or color added through the addition of pigments, depending on the taste of the manufacturer. Sometimes, there is white alabaster. In any case, the type of alabaster stone should be taken into account, or even main type of stone in the piece, since discontinuities often display higher porosity. Therefore, they will absorb a greater amount of color, thereby highlighting it even more, while the opaque areas of the stone will display less saturated shades. The paint may be oil-based, water-based or alcohol-based.
Regardless of the type of paint that is going to be applied, a particular technique is widely used in the staining of alabaster, which is quite useful in highlighting texture and veining. A base of nigrosine is laid, upon which the desired layers of paint will be applied. The application of nigrosine is often carried out through baths lasting 1 to 1 ½ hours. Likewise, a brown coloration can be achieved through immersion of the piece in a previously-heated solution of chromic acid.
• Waxes and other treatments. Waxes are typically used to brighten the stone, and they may be colored or colorless. There are no specific waxes for alabaster stone, so those used for floorings and wood are also used for alabaster. Vaseline, paraffin and whale oil are used for the external protection of the stone as they provide it with color, textures and shine.
• Varnishes are a special kind of paint. They are usually colourless and provide a layer that covers the entire object protecting it against external agents. They tend to affect the original properties of the stone, such as brightness or texture. An associated problem is that they eventually degrade since they become darker and crack, thereby losing their protective properties.
• Satin. When treating white alabaster with water at a given temperature for a specified time period, some of the properties of the stone can change. Externally, translucency is partially lost. Also, the colour changes to intense satin white and the brightness becomes wax-like.
• Cleaning. Depending on the exposure of the stone to external agents, large amounts of dirt and grease may accumulate on it, so that degreasers have to be used in order to clean the stone. The product used must be non-ionic, pH-neutral or slightly basic, and non-abrasive.
• Water-repellents. The main function of this product is to make sure that water or other liquids damage the stone. They are usually transparent and leave no traces once they have dried.