▁with ▁the ▁fuel ▁by ▁diffusion . ▁As ▁a ▁result , ▁the ▁fl ame ▁speed ▁is ▁limited ▁by ▁the ▁rate ▁of ▁diffusion .. ▁D iff usion ▁fl ames ▁tend ▁to ▁burn ▁slower ▁and ▁to ▁produce ▁more ▁so ot ▁than ▁prem ixed ▁fl ames ▁because ▁there ▁may ▁not ▁be ▁sufficient ▁ox id izer ▁for ▁the ▁reaction ▁to ▁go ▁to ▁completion , ▁although ▁there ▁are ▁some ▁exceptions ▁to ▁the ▁rule . ▁The ▁so ot ▁typically ▁produced ▁in ▁a ▁diffusion ▁fl ame ▁becomes ▁inc and es cent ▁from ▁the ▁heat ▁of ▁the ▁fl ame ▁and ▁l ends ▁the ▁fl ame ▁its ▁readily ▁ident ifiable ▁orange - yellow ▁color . ▁D iff usion ▁fl ames ▁tend ▁to ▁have ▁a ▁less - local ized ▁fl ame ▁front ▁than ▁prem ixed ▁fl ames . ▁ ▁The ▁context s ▁for ▁diffusion ▁may ▁vary ▁somewhat . ▁For ▁instance , ▁a ▁cand le ▁uses ▁the ▁heat ▁of ▁the ▁fl ame ▁itself ▁to ▁v apor ize ▁its ▁w ax ▁fuel ▁and ▁the ▁ox id izer ▁( ox y gen ) ▁diff uses ▁into ▁the ▁fl ame ▁from ▁the ▁surrounding ▁air , ▁while ▁a ▁gas light ▁fl ame ▁( or ▁the ▁safety ▁fl ame ▁of ▁a ▁b un sen ▁burn er ) ▁uses ▁fuel ▁already ▁in ▁the ▁form ▁of ▁a ▁v apor . ▁▁ ▁D iff usion ▁fl ames ▁are ▁often ▁studied ▁in ▁counter ▁flow ▁( also ▁called ▁opposed ▁jet ) ▁burn ers . ▁Their ▁interest ▁is ▁due ▁to ▁possible ▁application ▁in ▁the ▁fl ame let ▁model ▁for ▁tur bul ent ▁comb ust ion .