Coloring  Candles. — In  coloring  moulded  candles  the  dye  is
uniformly  mixed  with  the  melted  stock;  with  wax  candles  made  by
dipping,  the  candle  may  be  colored  throughout  by  mixing  the  dye
with  the  melted  stock  or  by  dipping  the  candle  at  intervals  during
formation,  or  once,  at  the  end,  into  stock  mixed  with  the  dye.  The
dipped  candle  may  thus  be  either  colored  uniformly  or  only  upon  the
surface,  or  in  variegated  colors.  Mineral  colors  are  inadvisable
owing  to  their  interference  with  combustion.  A  great  variety  of
aniline  colors  are  available.  As  a  rule  the  color  in  requisite  amount
is  dissolved  directly  in  a  small  portion  of  the  melted  stock  and  the
solution  strained  into  the  main  body  of  the  material.
Stearic  acid  dissolves  many  aniline  colors,  although  a  few  of  them
in  limited  quantities  only.  Its  acid  nature  causes  many  of  the  colors
to  fade.  The  basic  character  of  many  of  the  anilines  explains  the
readiness  with  which  they  are  dissolved  by  stearic  acid.  The  latter
is  heated  to  a  little  above  the  melting-point,  60°  to  65°  C.,  and  the
coloring  added.
The  quantity  of  the  coloring- matter  varies  between  0.05  and  o.oi
per  cent  of  the  weight  of  the  stearic  acid  according  to  the  depth  of
color  desired.  Care  should  be  taken  not  to  overheat  the  mass  lest
the  color  be  decomposed.
Some  of  the  colors  are  so  sensitive  to  heat  that  freshly  moulded
candles  in  which  they  are  used  appear  quite  colorless,  the  color
only  appearing  when  the  candles  have  become  quite  cold.  The
blue  colors  on  warming  also  sometimes  turn  reddish,  recovering  the
original  color  on  cooling.
