Damage to a specimen, or to the air scribe itself, can occur in several ways. Almost always it is due to operator error. The air scribe is very powerful and quite capable of quickly boring into mineralized bone or shell--with dire consequences. The reciprocating, or in-and-out, movement of the tool can actually pull the bit through the specimen in a series of millisecond-long bites that can leave the operator in a panic. The secret is to completely familiarize yourself with surface texture, color, and physical properties of both the fossil and the matrix--these are unique and vary greatly between specimens. Let the machine do the work. Knowledge of texture and color lets you know when to lighten up and pull away, and, for the most part, the movement of the chisel tip without any help except guidance from the operator is sufficient to reduce matrix to a fine debris. This is perhaps the most difficult technique to learn because it is human nature to think that force from our own muscles will make the job faster. Quite the contrary, the application of too much pressure only ensures that your lab will be filled with an incessant whining, your air scribe life span will be considerably reduced, and you may snap off fairly expensive chisel bits. In addition, because air scribes are so powerful, the bit should never be used as a lever. It is the reciprocating movement of the tip of the bit that effectively breaks apart the rock matrix. Wedging the bit into the rock, twisting, or levering off larger chunks not only breaks chisel bits, but also rapidly transforms your air scribe into a useless paperweight. With proper care, common sense, and regular lubrication, a pneumatic air scribe will last for years and will enable you to prepare fossils from nearly any matrix. Lab technicians are also finding that air scribes enable them to develop fossils in a way never before available to them, bringing out details of specimens impossible with older, more traditional technologies.

Pumps--PUMPS: two Ideco 1,000 hp,7"x10" Triplex; Prime movers--three 12 cyl. SACM900 kw each; Rotary Table--Ideco LR-275-K.DERRICK: Superior, 142''.BOP SYSTEM: Hydril, two annular, 21 1/2" 2,000 psiand 135" 5,000 psi; one double ram, 13 5/8 5,000 psi.CRANES: Two MAN, HDK 600 HM, HDK 260 HM.WORK AREA: Gabon.Arabian Drilling Co.ARABDRILL 8RIG DESIGN: Baker Marine Hull 150CONSTRUCTION: Promet Pvt. Ltd., Singapore, 1982.PERFORMANCE: Water depth--150''; Drilling depth--20,000''.QUARTERS: 80 persons.HULL: 174'' x 162.6'' x 18''.

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