Then a thin layer of fine mortar (called the setting bed) was spread over an area small enough to be worked before it dried ​ — perhaps less than a square yard.
टुकड़ों को सही जगह पर बिठाना आसान हो, इसके लिए कभी - कभी सतह पर एक रेखाचित्र भी बनाया जाता था ।