THE MOLDING SANDS OF MARYLAND INTRODUCTION. PURPOSE OF THE INVESTIGATION This investigation was undertaken by the State Geological Survey to ascertain what the possibilities were of finding molding sand deposits in the coastal plain formations in Anne Arundel, Calvert, Charles, Prince George's, and St. Mary's Counties. At the time the field work for the investigation was started, there was only one firm operating in this area. This company was not producing at that time, but was carrying on a prospecting campaign under its own auspices. FIELD WORK Molding sands in general will not stand the cost of long hauls to shipping points, especially if the roads are not particularly good. In planning the field work, this point was kept in mind and special attention was given to those areas where the transportation facilities by rail, wagon, or water were good, and in addition, to those that might get good transportation in the not distant future. TRANSPORTATION FACILITIES It is a well known fact that any natural resource located too remote from transportation facilities is practically worthless. This is very true of molding sand deposits. In general, no molding sand deposit will bear the cost of construction of a spur track more than 400 or 500 feet long. There are two main types of transportation facilities in this section of Maryland, viz., the railroads, and the water ways. The former is without doubt the most important and can be a great aid in developing some of the deposits found. Anne Arundel County has probably the best railroad facilities of any of the counties studied. The main lines of the Pennsylvania, Baltimore and Ohio, and the Washington, Baltimore and Annapolis railroads cross the northwestern part of this county. None of these lines will probably ever haul much sand for foundry purposes. The Baltimore and Annapolis Short Line Railroad traverses a section along the east side of the Severn River, which promises to produce some molding sand. The Annapolis;, Washington and Baltimore Railroad also crosses a promising territory between Academy Junction and Annapolis. The Chesapeake Beach Railroad crosses this county in the southern part and may be a carrier from small spotted deposits in this section. Prince George's County has the next best transportation facilities. The Pennsylvania, Baltimore and Ohio, and the Washington, Baltimore and Annapolis Railroads, all cross the northwestern part of the county. The Chesapeake Beach Railroad crosses this section in a southerly direction from Washington. The Pope's Creek Branch of the Pennsylvania Railroad, which leaves the main line at Bowie, serves the eastern and southern half of the county, and continues on southward through Charles County to Pope's Creek on the Potomac River. The Washington, Seaboard, and Norfolk Railroad which branches from the Pope's Creek Branch at Brandywine, continues south into Charles County, terminating at Mechanicsville in St. Mary's County. This is the only regular railroad transportation in St. Mary's County, and it is of only little importance, because it goes through the most northern tip of the county. The northern section of Calvert County is served by the Chesapeake Beach Railroad. It traverses a section which will probably be a small molding sand producer, unless land values rise due to the demand in this section for property for summer cottages. At present, water transportation can hardly be considered, because it consists of a weekly steamer plying between Baltimore and Washington, which is not capable of carrying any bulk freight unless shipped in barrels. This boat stops at all the wharfs on the Chesapeake Bay, the Patuxent River as far up as Lower Marlboro in Calvert County, and the Potomac as far up as Washington. The writer has been informed that it would be impossible at all times of the year to place a barge on the shores of Chesapeake Bay without proper breakwater facilities which would cost more to construct than any sand deposit could possibly warrant. This is because of the rather general heavy winds which blow on this shore with little warning. The cost of having a tug stand by for emergencies to pull a barge to sea in time of storm is also prohibitive. Thus, it seems that this type of transportation, at least on the shores of Chesapeake Bay in Calvert and St. Mary's counties, will have to be excluded. Barges or scows could be loaded with ease along the Patuxent or Potomac Rivers and hauled to Baltimore or Washington for shipment. In conclusion it may be said that the problem of making this section. of Maryland a producer of molding sand lies in the fact that the transportation facilities hinder the development of possibly good producing areas. This is true with the exception of the two northernmost counties of the group. LABORATORY WORK All the samples collected were shipped to Cornell University, where they were tested in accordance with a cooperative agreement between the State Geological Survey and the American Foundrymen's Association, as a result of which the latter organization is having studied all the samples collected by the various state surveys. The tests for permeability, fineness, and bond strength were carried out in accordance with the standard methods adopted by the American Foundrymen's Association. In addition, compression and tensile tests, as well as refractoriness tests were also made. Through the courtesy of Mr. W. M. Saunders, of Providence, R. I., dye adsorption tests have also been made on the samples. REQUISITE PROPERTIES OF MOLDING SANDS GENERAL STATEMENT The properties to be considered in sands used for foundry work are texture, permeability, bond strength, refractoriness, and life. Chemical composition is of value only in special cases, such as steel sands. The mineral composition may be considered in connection with the refractoriness of the sand. TEXTURE The texture of the sand is determined by the fineness test prescribed by the American Foundrymen's Association. The details of this test may be found in a publication of the Joint Committee on Molding Sand Research of the American Foundrymen's Association.1 The test consists of determining the clay substance in the sand by decantation after the clay has been suspended by shaking with water to which 25 cubic centimeters of sodium hydroxide solution (made by adding 10 grams of sodium hydroxide to 1000 cubic centimeters of water) are added. The grains are screened dry and the quantity retained on sieves with the following number of meshes to the inch: 6, 12, 20, 40, 40, 70, 100, 140, 200, 270, and pan, is determined. METHODS OF EXPRESSING FINENESS Many methods for expressing the fineness of sands and screened products have been suggested and their merits discussed. Probably the most widely known of these is the Scranton method. A very complete discussion of these different methods has been made by C. M. Nevin.2 A figure has been recently worked out by the author for grading molding sands, and it will be found accompanying the fineness test of the different samples. This figure is determined by taking the sum of the numbers obtained by dividing the percentage weight of the material retained on each screen by the number of meshes to the inch in the screen, the figure 410 being used for the material retained in the Pan. The clay substance is not taken into account. 1 American Foundrymen's Association, Tentatively Adopted Methods of Tests and Résumé of Activities of the Joint Committee on Molding Sand Research, June, 1924, pp. 54-57. New edition to appear in May, 1928. 2 Nevin, C. M., Albany Molding Sands of the Hudson Valley, New York State Museum, Bull. 263, 1925, pp. 31-49. |