identification  of  pen  size.  These  pens  are  avail- able   either   as   individual   fountain   pen   units, resembling  a  typical  fountain  pen,  or  as  a  set, having  a  common  handle  and  interchangeable  pen units. The pen shown in figure 2-31 is a part of a  set  of  technical  fountain  pens. Some reservoir pens for lettering are made so the point section will fit in a Leroy scriber. (The Leroy  letter  set  will  be  discussed  in  chapter  3.) These pens may also be used for any work that a  regular  technical  fountain  pen  is  used  for. Processes of Using the Technical Fountain Pen As  shown  in  figure  2-32,  you  must  hold  the technical fountain pen so that it is perpendicular to the drawing surface at all times. If you don’t hold the pen in the correct manner, the point will bevel  or  wear  unevenly  and  eventually  form  an elliptical point. With the point in this condition, the pen will produce lines of inconsistent widths. To fill the reservoir of a fountain pen, use the knob  located  on  the  barrel  opposite  the  point. When   you   turn   the   knob   counterclockwise,   a plunger is forced down into the barrel forcing out any ink remaining in the reservoir. Place the point end  of  the  pen  into  the  ink  and  turn  the  knob clockwise to pull the plunger up. As the plunger is  pulled  up,  ink  is  drawn  through  the  point, filling the reservoir. To fill the ink cartridge type of pen shown in figure 2-31, remove the cartridge from the body 142.327 Figure 2-32.-Drawing with a technical fountain pen. and insert the ink bottle dropper all the way into the   reservoir   cartridge.   Place   the   dropper   in contact with the bottom of the reservoir cartridge to prevent the ink from forming air bubbles. Fill the  cartridge  to  approximately  three-eighths  of  an inch from the top, then replace the cartridge and clamp  ring. Care and Cleaning of the Technical Fountain Pen The feed tube of the pen point is threaded (fig. 2-3 1). Along this threaded portion is an inclined channel that allows air to enter the ink reservoir. This channel must be free of dried ink or foreign particles   to   ensure   correct   ink   flow.   When cleaning the pen, scrub the threads and channel with a brush, such as a toothbrush, wetted with a cleaning solution of soap and water. A cleaning pin (a tiny weighted needle) is made so that it fits into  the  feed  tube  and  point  (fig,  2-31).  This cleaning pin assures a clear passage of ink from the reservoir to the point. Usually, a light shake of  the  pen  will  set  the  cleaning  pin  in  motion, removing any particles that settle in the tube when not  in  use.  (Do  not  shake  the  pen  over  your drawing   board.) If the pen is not used frequently, the ink will dry, clogging the point and feed tube. When the pen becomes clogged, soak the pen in pen cleaner or  ammonia  water  until  it  will  unscrew  with  little or no resistance. A better practice is to clean the pen  before  you  put  it  away  if  you  know  in advance that you will not be using it for several days. The cleaning pin must be handled with care, especially the smaller sizes. A bent or damaged cleaning pin will never fit properly into the feed tube  and  point. DRAWING   INK A  draftsman’s  drawing  ink  is  commonly  called INDIA  INK.  Drawing  ink  consists  of  a  pigment (usually  powdered  carbon)  suspended  in  an ammonia-water solution. Ink that has thickened by age or evaporation maybe thinned slightly by adding a few drops of solution of four parts aqua ammonia  to  one  part  distilled  water.  After  the  ink dries  on  paper,  it  is  waterproof.  Drawing  ink  is available   in   many   different   colors,   but   for construction and engineering drawings, black ink is  preferred  for  reproduction  and  clarity.  Small 2-25