﻿CLAYS 
  OF 
  NEW 
  YORK 
  809 
  

  

  Artificial 
  glazes 
  are 
  used 
  to 
  some 
  extent 
  on 
  the 
  better 
  grade 
  of 
  

   stoneware 
  made 
  at 
  the 
  present 
  day. 
  

  

  Stoneware 
  is 
  sometimes 
  coated 
  with 
  a 
  slip 
  of 
  white 
  clay. 
  

  

  Burning 
  stoneware 
  

  

  Stoneware 
  is 
  commonly 
  burned 
  in 
  round 
  kilns. 
  The 
  articles 
  

   are 
  piled 
  one 
  on 
  top 
  of 
  the 
  other 
  till 
  the 
  kiln 
  is 
  filled, 
  but 
  they 
  

   are 
  set 
  in 
  such 
  a 
  way 
  as 
  not 
  to 
  interfere 
  with 
  an 
  even 
  draft 
  through- 
  

   out 
  the 
  kiln, 
  and 
  the 
  larger 
  pieces 
  are 
  placed 
  in 
  the 
  center. 
  If 
  

   both 
  salt 
  glazed 
  and 
  slip 
  glazed 
  wares 
  are 
  burned 
  in 
  the 
  kiln 
  at 
  the 
  

   same 
  time, 
  the 
  latter 
  have 
  to 
  be 
  protected 
  from 
  the 
  salt 
  vapor 
  in 
  

   some 
  way. 
  

  

  The 
  time 
  of 
  burning 
  depends 
  partly 
  on 
  the 
  size 
  of 
  the 
  kiln, 
  arid 
  

   partly 
  on 
  the 
  clay. 
  It 
  may 
  be 
  as 
  short 
  as 
  30 
  hours 
  or 
  as 
  long 
  as 
  90. 
  

  

  The 
  temperature 
  attained 
  in 
  burning 
  stoneware 
  also 
  depends 
  on 
  

   the 
  clay. 
  Experiments 
  made 
  in 
  Ohio 
  show 
  that 
  the 
  temperature 
  

   ranges 
  from 
  about 
  1850° 
  to 
  2000° 
  F. 
  Other 
  experiments 
  made 
  

   by 
  the 
  writer 
  indicate 
  that 
  in 
  the 
  case 
  of 
  the 
  'New 
  Jersey 
  semi-fire 
  

   clays 
  the 
  temperature 
  in 
  stoneware 
  kilns 
  reached 
  2300° 
  F. 
  at 
  

   times. 
  

  

  The 
  kilns 
  used 
  in 
  burning 
  stoneware 
  are 
  either 
  up-draft 
  or 
  

   down-draft, 
  both 
  round 
  and 
  rectangular. 
  

  

  Glazing 
  ivhite 
  earthenware 
  and 
  porcelain 
  

  

  In 
  this 
  gi'ade 
  of 
  ware, 
  the 
  glazing 
  and 
  burning 
  are 
  not 
  done 
  m 
  

   one 
  operation, 
  as 
  in 
  the 
  case 
  of 
  the 
  stoneware, 
  but, 
  on 
  the 
  con- 
  

   trary, 
  the 
  ware 
  after 
  molding 
  is 
  first 
  burned 
  to 
  a 
  comparatively 
  low 
  

   temperature, 
  after 
  which 
  it 
  is 
  dipped 
  in 
  the 
  glaze 
  and 
  burned 
  a 
  

   second 
  time. 
  In 
  the 
  case 
  of 
  white 
  earthenware 
  the 
  temperature 
  

   of 
  the 
  second 
  burning 
  is 
  lower 
  than 
  that 
  of 
  the 
  first, 
  while 
  in 
  the 
  

   case 
  of 
  the 
  porcelain 
  it 
  is 
  higher. 
  

  

  The 
  production 
  of 
  a 
  glaze 
  on 
  the 
  surface 
  of 
  either 
  porcelain 
  or 
  

   earthenware, 
  free 
  from 
  the 
  numerous 
  defects 
  to 
  which 
  such 
  mate- 
  

   rials 
  are 
  very 
  liable, 
  is 
  often 
  attended 
  by 
  considerable 
  difficulty. 
  

  

  The 
  glaze 
  on 
  pottery 
  consists 
  of 
  a 
  fusible 
  mixture 
  which 
  is 
  

   applied 
  to 
  the 
  surface 
  of 
  the 
  ware, 
  either 
  when 
  it 
  is 
  still 
  in 
  a 
  green 
  

  

  