﻿CLAYS 
  OF 
  NEW 
  YORK 
  

  

  651 
  

  

  enamel, 
  and 
  a 
  glaze 
  which 
  shall 
  be 
  free 
  from 
  cracks 
  or 
  crazes; 
  the 
  

   latter 
  are 
  due 
  to 
  the 
  body 
  and 
  the 
  glaze 
  having 
  a 
  different 
  coefficient 
  

   of 
  expansion. 
  

  

  Enamel 
  brick 
  are 
  made 
  of 
  two 
  different 
  sizes, 
  known 
  as 
  the 
  

   English 
  and 
  the 
  American 
  size, 
  the 
  former 
  being 
  9x4^x3, 
  the 
  

   latter 
  8f 
  x4ix2f 
  . 
  

  

  Many 
  manufacturers 
  are 
  able 
  to 
  produce 
  a 
  wide 
  range 
  of 
  colors; 
  

   the 
  number 
  is 
  constantly 
  being 
  added 
  to. 
  Owing 
  to 
  the 
  ex- 
  

   pense 
  of 
  manufacture, 
  the 
  cost 
  of 
  these 
  bricks 
  is 
  usually 
  high, 
  and 
  

   varies 
  from 
  $60 
  to 
  $90 
  a 
  thousand. 
  

  

  The 
  body 
  of 
  the 
  brick 
  is 
  usually 
  made 
  of 
  several 
  different 
  clays, 
  

   and 
  much 
  depends 
  on 
  the 
  selection 
  of 
  the 
  proper 
  material. 
  On 
  

   this 
  mixture 
  the 
  method 
  of 
  burning 
  sometimes 
  also 
  depends. 
  

  

  The 
  clays 
  used 
  for 
  the 
  body 
  of 
  the 
  brick 
  are 
  molded 
  either 
  by 
  the 
  

   soft 
  mud, 
  dry 
  press, 
  or 
  stiff 
  mud 
  process. 
  The 
  glaze 
  is 
  sometimes 
  

   applied 
  to 
  green 
  bricks 
  before 
  being 
  burned; 
  or 
  at 
  other 
  times 
  the 
  

   brick 
  is 
  first 
  fired, 
  the 
  glaze 
  then 
  applied, 
  and 
  the 
  two 
  subjected 
  to 
  

   a 
  second 
  burning, 
  which 
  is 
  at 
  a 
  lower 
  temperature 
  than 
  the 
  first. 
  

   The 
  one 
  is 
  known 
  as 
  the 
  single 
  fire 
  process, 
  the 
  other 
  as 
  the 
  double 
  

   fire 
  process. 
  

  

  Enamel 
  bricks 
  are 
  usually 
  made 
  with 
  an 
  indentation 
  on 
  the 
  upper 
  

   and 
  lower 
  faces. 
  In 
  laying 
  a 
  wall 
  the 
  mortar 
  is 
  put 
  in 
  this 
  space, 
  in 
  

   such 
  quantity 
  that 
  when 
  the 
  bricks 
  are 
  pressed 
  together 
  a 
  thin 
  

   layer 
  of 
  it 
  is 
  forced 
  out 
  toward 
  the 
  edges 
  and 
  furnishes 
  sufficient 
  

   binding 
  material. 
  This 
  does 
  away 
  with 
  " 
  pointing 
  '' 
  at 
  the 
  joints, 
  

   and 
  a 
  wall 
  properly 
  laid 
  should 
  show 
  almost 
  no 
  mortar 
  between 
  

   the 
  courses. 
  In 
  consequence 
  of 
  this 
  mode 
  of 
  laying, 
  every 
  brick 
  

   should 
  be 
  true 
  to 
  the 
  standard 
  size 
  in 
  order 
  to 
  secure 
  a 
  regular 
  and 
  

   perfect 
  bond. 
  It 
  is, 
  therefore, 
  necessary 
  to 
  know 
  the 
  exact 
  shrink- 
  

   age 
  that 
  occurs 
  in 
  burning, 
  and 
  to 
  allow 
  for 
  it 
  by 
  giving 
  to 
  the 
  

   dies 
  used 
  in 
  pressing 
  the 
  brick 
  the 
  proper 
  amount 
  of 
  ^' 
  over 
  size." 
  

  

  In 
  a 
  good 
  enamel 
  brick 
  the 
  enamel 
  should 
  adhere 
  so 
  tenaciously 
  

   to 
  the 
  body 
  that 
  it 
  will 
  not 
  separate 
  or 
  crack 
  under 
  pressure 
  till 
  the 
  

   body 
  of 
  the 
  brick 
  fails. 
  

  

  