▁an ▁even ▁manner ▁at ▁lower ▁temper atures ▁than ▁sol der ▁or ▁tar . ▁Also , ▁since ▁so aps ▁and ▁cand les ▁are ▁sc ented ▁and ▁col oured , ▁t anks ▁designed ▁for ▁mel ting ▁these ▁subst ances ▁need ▁to ▁be ▁spe cially ▁pol ished ▁to ▁ensure ▁there ▁is ▁no ▁cont am ination ▁between ▁different ▁sc ented / col oured ▁cand les ▁or ▁soap . ▁For ▁this ▁reason , ▁there ▁are ▁mel ting ▁t anks ▁that ▁are ▁spe cially ▁co ated ▁for ▁cand le ▁w ax ▁mel ting . ▁ ▁Types ▁W ax ▁mel ters , ▁such ▁as ▁mel ting ▁t anks , ▁are ▁generally ▁class ified ▁as ▁either ▁' direct ▁he ating ' ▁or ▁' water ▁jack et ▁he ating '. ▁A ▁third ▁type ▁is ▁known ▁as ▁the ▁con ve ction ▁mel ter . ▁ ▁A ▁water ▁jack et ▁mel ter ▁is ▁generally ▁preferred ▁if ▁more ▁than ▁ 4 0 ▁lit res ▁or ▁so ▁are ▁to ▁be ▁pou red . ▁A ▁mel ter ▁should ▁be ▁pol ished ▁and ▁have ▁a ▁co ating ▁to ▁prevent ▁cross ▁cont am ination ▁if ▁heavily ▁sc ented ▁or ▁col oured ▁subst ances ▁are ▁to ▁be ▁used . ▁ ▁Direct ▁heat ▁Direct ▁heat ▁mel ters ▁are ▁generally ▁made ▁from ▁al umin ium ▁and ▁can ▁heat ▁up ▁to ▁over ▁. ▁The ▁uses ▁vary ▁from ▁w ax ▁to ▁sol der . ▁These ▁mel ters ▁have ▁the ▁he ating ▁element ▁placed ▁in ▁contact ▁with ▁the ▁al umin ium , ▁which ▁is ▁directly ▁against ▁the ▁subst ance ▁to ▁be ▁m elt ed ,