▁( M g O ), ▁for ▁example . ▁Therefore , ▁in ▁the ▁case ▁of ▁using ▁str ont ium ▁nit rate ▁and ▁mag nes ium , ▁to ▁produce ▁a ▁red ▁colored ▁fl ame ▁that ▁is ▁not ▁over - power ed ▁by ▁the ▁white ▁light ▁from ▁the ▁burning ▁fuel , ▁a ▁ch lor ine ▁don or ▁is ▁provided ▁in ▁the ▁py rote chn ic ▁mixture , ▁so ▁that ▁str ont ium ▁ch lor ide ▁can ▁also ▁form ▁in ▁the ▁fl ame , ▁cool ing ▁it ▁so ▁that ▁the ▁white ▁light ▁of ▁M g O ▁is ▁greatly ▁reduced . ▁ ▁C ool ing ▁the ▁fl ame ▁in ▁this ▁manner ▁also ▁length ens ▁the ▁reaction ▁rate ▁so ▁that ▁the ▁mixture ▁has ▁an ▁appreci able ▁burn ▁time . ▁Poly vin yl ▁ch lor ide ▁( P VC ) ▁is ▁a ▁typical ▁organ ic ▁fuel ▁in ▁colored ▁light ▁for ▁this ▁purpose . ▁ ▁Some ▁modern ▁designs ▁use ▁compos itions ▁that ▁produce ▁little ▁to ▁no ▁visible ▁light ▁and ▁radi ate ▁mainly ▁in ▁inf ra red , ▁being ▁visible ▁only ▁on ▁night ▁vision ▁equipment . ▁ ▁Types ▁▁ ▁There ▁are ▁three ▁types ▁of ▁trac ers : ▁bright ▁trac er , ▁sub du ed ▁trac er ▁and ▁dim ▁trac er . ▁Bright ▁trac ers ▁are ▁the ▁standard ▁type , ▁which ▁start ▁burning ▁very ▁shortly ▁after ▁exit ing ▁the ▁m uzz le . ▁ ▁A ▁dis adv antage ▁of ▁bright ▁trac ers ▁is ▁that ▁they ▁give ▁away ▁the ▁shoot er ' s ▁location ▁to ▁the ▁enemy ; ▁as ▁a ▁military ▁ad age ▁puts