﻿CLAYS 
  OF 
  NEW 
  YOKK 
  775 
  

  

  done 
  any 
  harm. 
  The 
  soluble 
  salts 
  may 
  also 
  get 
  into 
  the 
  clay 
  from 
  

   some 
  of 
  the 
  materials 
  used 
  to 
  color 
  the 
  tile 
  artificially, 
  umber, 
  for 
  

   example, 
  being 
  seldom 
  free 
  from 
  sulfate 
  of 
  lime. 
  

  

  Floor 
  tile 
  should 
  be 
  burned 
  to 
  a 
  condition 
  of 
  great 
  density, 
  in 
  

   order 
  that 
  they 
  may 
  not 
  absorb 
  water, 
  nor 
  permit 
  the 
  entrance 
  of 
  

   dirt 
  into 
  their 
  pores, 
  rendering 
  their 
  cleaning 
  more 
  difficult. 
  

  

  Langenbeck 
  (Chemistry 
  of 
  pottery, 
  p. 
  156) 
  gives 
  the 
  following 
  

   percentages 
  of 
  water 
  absorbed 
  by 
  floor 
  tile 
  of 
  different 
  colors. 
  

  

  Water 
  absorption 
  of 
  floor 
  tile 
  

  

  Color 
  of 
  the 
  clay 
  Extremes 
  Averages 
  

  

  Salmon 
  1.5—9.1 
  5.8 
  

  

  Buff 
  1.9— 
  7.2 
  4.6 
  

  

  Light 
  gray 
  1.9—8.5 
  5.8 
  

  

  Darkgray 
  2.0— 
  5.8 
  4.4 
  

  

  Chocolate 
  0.0— 
  7.4 
  4.8 
  

  

  Eed 
  1.5— 
  8.4 
  6.0 
  

  

  Black 
  4.4 
  — 
  10.3 
  7.5 
  

  

  Fawn 
  8.3 
  

  

  In 
  the 
  manufacture 
  of 
  encaustic 
  tile, 
  the 
  clay 
  that 
  is 
  to 
  form 
  the 
  

   surface 
  of 
  the 
  tile 
  and 
  give 
  the 
  pattern 
  is 
  'charged 
  into 
  the 
  mold 
  

   first, 
  while 
  the 
  clay 
  that 
  makes 
  up 
  the 
  body 
  is 
  then 
  put 
  in 
  on 
  top 
  

   and 
  the 
  whole 
  subjected 
  to 
  pressure 
  in 
  the 
  machine. 
  The 
  molds 
  

   can 
  be 
  filled 
  by 
  machinery 
  when 
  the 
  color 
  of 
  the 
  tile 
  is 
  solid. 
  

  

  With 
  encaustic 
  tile 
  the 
  molds 
  have 
  to 
  be 
  filled 
  by 
  hand. 
  Where 
  

   the 
  pattern 
  is 
  made 
  up 
  of 
  clays 
  of 
  several 
  different 
  colors, 
  a 
  frame- 
  

   work 
  of 
  brass 
  strips, 
  so 
  arranged 
  as 
  to 
  mark 
  the 
  boundaries 
  of 
  each 
  

   color 
  is 
  first 
  set 
  into 
  the 
  mold, 
  thus 
  dividing 
  it 
  up 
  into 
  cells. 
  Into 
  

   each 
  of 
  these 
  the 
  color 
  is 
  charged 
  by 
  means 
  of 
  a 
  small 
  hand 
  scoop, 
  

   till 
  every 
  cell 
  is 
  filled 
  with 
  the 
  color 
  whose 
  boundaries 
  it 
  incloses. 
  

   The 
  framework 
  is 
  then 
  withdrawn 
  from 
  the 
  mold, 
  and 
  the 
  latter 
  

   filled 
  up 
  to 
  the 
  top 
  with 
  the 
  clay 
  that 
  forms 
  the 
  body 
  of 
  the 
  tile. 
  

  

  It 
  is 
  essential 
  that 
  the 
  clay 
  forming 
  the 
  face 
  and 
  that 
  which 
  

   serves 
  as 
  the 
  backing 
  should 
  have 
  the 
  same 
  expansion, 
  otherwise 
  

  

  