▁the ▁amount ▁and ▁type ▁of ▁paint ▁medium ▁used ▁in ▁the ▁gla ze . ▁The ▁medium , ▁base , ▁or ▁vehicle ▁is ▁the ▁mixture ▁to ▁which ▁the ▁dry ▁p ig ment ▁is ▁added . ▁D ifferent ▁media ▁can ▁increase ▁or ▁decrease ▁the ▁rate ▁at ▁which ▁oil ▁pain ts ▁dry . ▁ ▁O ften , ▁because ▁a ▁paint ▁is ▁too ▁op aque , ▁pain ters ▁will ▁add ▁a ▁medium ▁like ▁lin seed ▁oil ▁or ▁alk yd ▁to ▁the ▁paint ▁to ▁make ▁them ▁more ▁transparent ▁and ▁p li able ▁for ▁the ▁purposes ▁of ▁gla zing . ▁While ▁these ▁media ▁are ▁usually ▁liqu ids , ▁there ▁are ▁solid ▁and ▁semi - sol id ▁media ▁used ▁in ▁the ▁making ▁of ▁pain ts ▁as ▁well . ▁For ▁example , ▁many ▁classical ▁oil ▁pain ters ▁have ▁also ▁been ▁known ▁to ▁use ▁ground ▁glass ▁and ▁semi - sol id ▁res ins ▁to ▁increase ▁the ▁transl uc ency ▁of ▁their ▁paint . ▁ ▁O il ▁painting ▁In ▁oil ▁painting , ▁the ▁simplest ▁form ▁of ▁a ▁gla ze ▁is ▁a ▁thin , ▁o ily , ▁transparent ▁layer ▁of ▁paint ▁spread ▁over ▁the ▁top ▁of ▁an ▁op aque ▁passage ▁that ▁has ▁been ▁given ▁some ▁time ▁to ▁dry . ▁Light ▁travel s ▁through ▁the ▁gla ze ▁and ▁is ▁reflected ▁back ▁off ▁of ▁the ▁op aque ▁layer ▁below . ▁This ▁can ▁cause ▁a ▁g low ing ▁effect ▁similar ▁to ▁looking ▁at ▁a ▁bright ly ▁lit ▁white ▁wall ▁behind ▁a ▁film ▁of ▁colored ▁c ello ph ane . ▁The ▁thin ▁o ily ▁layers ▁of ▁a ▁gla ze