June 5, 2014
In this month’s issue…
In this issue… we talk about the various standard stone finishes available for use on Indiana Limestone. Ernie provide his “2 Cents” this month on the subject of stone fabrication schedules.
INDIANA LIMESTONE FINISHES –
Descriptions and Adaptability
Specifiers should always request and receive samples of Indiana Limestone for approval of texture, color, and particularly finish. While most finishes are generally understood and agreed on by limestone producers,innovation in machine types which reduce costs and simplify production may result in variations in surface appearance. The durability and ultimate value of the stone is not changed in any case.
1. SMOOTH FINISH
This is the least textural of standard limestone finishes and presents a minimum of surface interruption to the eye or to touch. The degree of smoothness is determined by the finishing method applied. Smooth finishes are produced in a variety of ways by a number of different machines and are sometimes called out as plane honed, grinder, machine, carborundum, bugged, or circular sander. All of these are classified as smooth finish. Specifying these individual applied methods will be considered as smooth, and one or more of the applicable methods may be used by the fabricator. The smooth finish should not be confused with polished. Indiana Limestone with a polished finish may not yield the generally accepted degree of reflectivity and uniformity which appears on more crystalline stones so finished. ILI does not recommend specifying a polished finish on Indiana Limestone. Some of the techniques for applying smooth finish are applicable only to flat surfaces. Where complex, curved, or molded surfaces occur in a building design, the producer may choose to use a variety of machines to produce them. Where finished stone will tend to be viewed at close range, such as in interior work or at building entrance features, matching finish types can be achieved by the use of matching production methods.
2. COARSE AND TEXTURED FINISHES
A. PLUCKED: This is a machine finish obtained by rough planning the surface of the stone, thus breaking or plucking out small particles. This gives an interesting rough texture. Plucked is occasionally used as a finish on the stone trim of buildings faced with a smooth finish.
B. MACHINE TOOLED: This finish consists of cutting parallel, concave grooves in the stone. It is available in four, six or eight bats (grooves) to the inch. The depth of the groove varies with the number of bats used but will range from 1/32″ to 1/16″ deep. Machine tooling is used primarily on ashlar surfaces. Tooled trim work can be economically machine cut only along the long dimension of the stone.
C. BUSHHAMMER: This finish is pneumatically applied, either by hand or by machine, and can range in texture from light to fairly coarse, though maximum relief will never exceed a fraction of an inch. Some variation in finish can occur by interchange of tools in the application head. This finish is best applied on flat surfaces, but can be applied by hand on radial surfaces. Coarser finishes require thicker stones. ILI recommends that the designer consult either with ILI or a member fabricator prior to specifying a bush hammer finish.
D. SPLIT FACE: A rough, uneven, concave-convex finish produced by the splitting action of a guillotine knife. The stones are split to the specified wall thickness (usually 3″ to 4: thick), in random lengths, 1′ to 4′ long, and sawed to the specified course heights. This finish is limited to stone sizes 4′ by 1′ to 4′ high. Split face is available in ashlar stone veneer only. The rough, natural appearance creates maximum light and shadow contrast. It is used extensively for residential, commercial, and ecclesiastical buildings, interior and exterior to emphasize horizontal lines and create a massive appearance. When using this finish, specify color of stone only (buff, gray, or variegated). The stones will represent a complete range of grades, fine through coarse.
E. ROCK FACE: Rock face is a finish that has been dressed by machine or by hand to produce a bold, convex projection along the face of the stone. This finish provides a bolder, more massive appearance than split face.
F. CHAT SAWED: This finish results from the use of a coarse abrasive during the gang sawing operation. It has a coarse pebbled surface which closely resembles the appearance of sand blasting. It will sometimes contain shallow saw marks or parallel scores. Direction of the score or saw marks will be vertical and/or horizontal in the wall unless the direction is specified. This finish may have a slight variation in color due to the presence of iron oxide in the saw slurry resulting from the wearing of the steel saw blades. This finish can be applied only to flat surfaces and is particularly suited to the various types of ashlar. For best economy, its use should be confined to the coarser grades of stone.
G. SHOT SAWED: This is a coarse, uneven finish ranging from a pebbled surface to one ripped with irregular, roughly parallel grooves. The random markings are obtained by using steel shot in the gang sawing process in combination with chat sand. The steel shot rusts during this process, permitting varying amounts of rust stain to develop—adding permanent brown tones to the natural color variations. It is not possible to obtain complete uniform distribution of the shot grooves over the entire surface of the stone. Some portions will have only a chat sawed finish. A shot sawed finish can be applied to flat surfaces only and should be confined to the coarser grades. Direction of the grooves will be vertical and/or horizontal in the stone unless the direction is specified.
Due to changes in fabrication methods, the chat and shot-sawn finishes are no longer widely produced by the industry. Those interested in either finish should contact ILI or its member companies for information as to their availability.
H. CUSTOM TEXTURES: Many fabricators produce specialty textures, which may be linear or non-linear. Linear textures usually have parallel ribs and grooves. It is generally more economical to run textures the long dimension of the stone. The ribs and grooves may be quite smooth with a neat and tailored look, or rough and broken to produce a craggy, almost random appearance with an occasional area of “break-out” or “scoop-out” across the raised portions of the texture. These textures are well suited to the coarser grades of stone.
Ernie’s Two Cents
In the age of “RIGHT NOW” it is assumed more often than not, that there is a shelf sitting somewhere in Southern Indiana which magically holds all of the cut stone needed for all of the projects going on all over the country. Sadly, that is not the case.
On bid day, we will issue you a formal proposal stating the material cost, freight allowance and lead time based on receipt of approved shop drawings and/or sequencing. Once we receive your approved shop drawings back and/or the sequencing (where you want to start on the building and in what direction you wish to go), the clock starts on your lead time. Typically it is a 5-7 or 6-8 week lead time, this time frame is determined by the difficulty of the work and our current work load. This time frame is also for the initial load NOT the entire project. Once we start shipping, we continue to fabricate until your project is fully completed. If it is necessary for us to hold the initial load and not ship due to site conditions, etc – we will move on to fabricate other projects and come back to your once the initial load is shipped to the project site.
While we do our best to accommodate your project needs, we simply cannot adjust fabrication scheduling on a week to week or day to day need. In the meantime, if you come across that shelf….let us know.
Our project spotlight this month is the Kokomo High School Football Stadium in Kokomo, Indiana. On this project we supplied a wide variety of Indiana Limestone veneer, trim and accent pieces. The masonry contractor of this project is D&K Masonry .