Smoke screen A smoke screen is smoke released to mask the movement or location of military units such as infantry , tank s , aircraft or ships . Smoke screens are commonly deployed either by a canister ( such as a grenade ) or generated by a vehicle ( such as a tank or a warship ) . Whereas smoke screens would originally have been used to hide movement from enemies ' line of sight , modern technology means that they are now also available in new forms ; they can screen in the infrared as well as visible spectrum of light to prevent detection by infrared sensors or viewers , and also available for vehicles is a superdense form used to prevent laser beams of enemy target designators or range finders on vehicles . Technology . Smoke grenades . These are canister - type grenades used as a ground - to - ground or ground - to - air signaling device . The body consists of a steel sheet metal cylinder with a few emission holes on top and on the bottom to allow smoke release when the smoke composition inside the grenade is ignited . In those that produce colored smoke , the filler consists of 250 to 350 grams of colored ( red , green , yellow or violet ) smoke mixture ( mostly potassium chlorate , sodium bicarbonate , lactose and a dye ) . In those that produce screening smoke , the filler usually consists of HC smoke mixture ( hexachloroethane / zinc ) or TA smoke mixture ( terephthalic acid ) . Another type of smoke grenade is filled with white phosphorus ( WP ) , which is spread by explosive action . The phosphorus catches fire in the presence of air , and burns with a brilliant yellow flame , while producing copious amounts of white smoke ( phosphorus pentoxide ) . WP grenades double as incendiary grenade s . Smoke shell . " See also Smoke shells . " Artillery and mortar s can also fire smoke generating munitions , and are the main means of generating tactical smokescreens on land . As with grenades , artillery shells are available as both emission type smoke shell , and bursting smoke shell . Mortars nearly always use bursting smoke rounds because of the smaller size of mortar bombs and the greater efficiency of bursting rounds . Smoke generators . Very large or sustained smoke screens are produced by a smoke generator . This machine heats a volatile material ( typically oil or an oil based mixture ) to evaporate it , then mixes the vapor with cool external air at a controlled rate so it condenses to a mist with a controlled droplet size . Cruder designs simply boiled waste oil over a heater , while more sophisticated ones sprayed a specially formulated oily composition ( " fog oil " ) through nozzles onto a heated plate . Choice of a suitable oil , and careful control of cooling rate , can produce droplet sizes close to the ideal size for Mie scattering of visible light . This produces a very effective obscuration per weight of material used . This screen can then be sustained as long as the generator is supplied with oil , and — especially if a number of generators are used — the screen can build up to a considerable size . One 50 gallon drum of fog oil can obscure of land in 15 minutes . Whilst producing very large amounts of smoke relatively cheaply , these generators have a number of disadvantages . They are much slower to respond than pyrotechnic sources , and require a valuable piece of equipment to be sited at the point of emission of the smoke . They are also relatively heavy and not readily portable , which is a significant problem if the wind shifts . To overcome this latter problem they may be used in fixed posts widely dispersed over the battlefield , or else mounted on specially adapted vehicles . An example of the latter is the M56 Coyote generator . Many armoured fighting vehicles can create smoke screens in a similar way , generally by injecting diesel fuel onto the hot exhaust . Naval methods . Warships have sometimes used a simple variation of the smoke generator , by injecting fuel oil directly into the smoke stack . An even simpler method that was used in the days of steam - propelled warships was to restrict the supply of air to the boiler . This resulted in incomplete combustion of the coal or oil , which produced a thick black smoke . Because the smoke was black , it absorbed heat from the sun and tended to rise above the water . Therefore navies turned to various chemicals , such as titanium tetrachloride , that produce a white , low - lying cloud . Infrared smokes . The proliferation of thermal imaging FLIR systems on the battlefields necessitates the use of obscurant smokes that are effectively opaque in the infrared part of electromagnetic spectrum . To achieve this , the particle size and composition of the smokes has to be adjusted . One of the approaches is using an aerosol of burning red phosphorus particles and aluminium coated glass fibers ; the infrared emissions of such smoke curtains hides the weaker emissions of colder objects behind it , but the effect is only short - lived . Carbon ( most often graphite ) particles present in the smokes can also serve to absorb the beams of laser designator s . Yet another possibility is a water fog sprayed around the vehicle ; the presence of large droplets absorbs in infrared band and additionally serves as a countermeasure against radar s in 94 GHz band . Other materials used as visible / infrared obscurants are micropulverized flakes of brass or graphite , particles of titanium dioxide , or terephthalic acid . Older systems for production of infrared smoke work as generators of aerosol of dust with controlled particle size . Most contemporary vehicle - mounted systems use this approach . However the aerosol stays airborne only for a short time . The brass particles used in some infrared smoke grenade s are typically composed of 70 % copper and 30 % zinc . They are shaped as irregular flakes with a diameter of about 1 . 7 µm and thickness of 80 - 320 nm . A dry powder fire extinguisher is said to be a good improvised system for production of aerosol effective even in far infrared . Some experimental obscurants work in both infrared and millimeter wave region . They include carbon fiber s , metal coated fibers or glass particles , metal microwires , particles of iron and of suitable polymers . Chemicals used for smoke generation . Zinc chloride . Zinc chloride smoke is grey - white and consists of tiny particles of zinc chloride . The most common mixture for generating these is the zinc chloride smoke mixture ( HC ) , consisting of hexachloroethane , grained aluminium and zinc oxide . The smoke consists of zinc chloride , zinc oxychlorides , and hydrochloric acid , which absorb the moisture in the air . The smoke also contains traces of organic chlorinated compounds , phosgene , carbon monoxide , and chlorine . Its toxicity is caused mainly by the content of strongly acidic hydrochloric acid , but also due to thermal effects of reaction of zinc chloride with water . These effects cause lesion s of the mucous membrane s of the upper airways . Damage of the lower airways can manifest itself later as well , due to fine particles of zinc chloride and traces of phosgene . In high concentrations the smoke can be very dangerous when inhaled . Symptoms include dyspnea , retrosternal pain , hoarseness , stridor , lachrymation , cough , expectoration , and in some cases haemoptysis . Delayed pulmonary edema , cyanosis or bronchopneumonia may develop . The smoke and the spent canisters contain suspected carcinogen s . The prognosis for the casualties depends on the degree of the pulmonary damage . All exposed individuals should be kept under observation for 8 hours . Most affected individuals recover within several days , with some symptoms persisting for up to 1 – 2 weeks . Severe cases can suffer of reduced pulmonary function for some months , the worst cases developing marked dyspnea and cyanosis leading to death . Respirators are required for people coming into contact with the zinc chloride smoke . Chlorosulfuric acid . Chlorosulfuric acid ( CSA ) is a heavy , strongly acidic liquid . When dispensed in air , it readily absorbs moisture and forms dense white fog of hydrochloric acid and sulfuric acid . In moderate concentrations it is highly irritating to eyes , nose , and skin . When chlorosulfuric acid comes in contact with water , a strong exothermic reaction scatters the corrosive mixture in all directions . CSA is highly corrosive , so careful handling is required . Low concentrations cause prickling sensations on the skin , but high concentrations or prolonged exposure to field concentrations can cause severe irritation of the eyes , skin , and respiratory tract , and mild cough and moderate contact dermatitis can result . Liquid CSA causes acid burn s of skin and exposure of eyes can lead to severe eye damage . Affected body parts should be washed with water and then with sodium bicarbonate solution . The burns are then treated like thermal burns . The skin burns heal readily , while cornea burns can result in residual scarring . Respirators are required for any concentrations sufficient to cause any coughing , irritation of the eyes or prickling of the skin . Titanium tetrachloride . Titanium tetrachloride ( FM ) is a yellow , non - flammable , corrosive liquid . In contact with damp air it hydrolyzes readily , resulting in a dense white smoke consisting of droplets of hydrochloric acid and particles of titanium oxychloride . The titanium tetrachloride smoke is irritant and unpleasant to breathe . It is dispensed from aircraft to create vertical smoke curtains , and during World War II it was a favorite smoke generation agent on warships . Goggles or a respirator should be worn when in contact with the smoke , full protective clothing should be worn when handling liquid FM . In direct contact with skin or eyes , liquid FM causes acid burns . Phosphorus . Red phosphorus and white phosphorus ( WP ) are red or waxy yellow or white substances . White phosphorus is pyrophoric - can be handled safely when under water , but in contact with air it spontaneously ignites . It is used as an incendiary . Both types of phosphorus are used for smoke generation , mostly in artillery shells , bombs , and grenades . White phosphorus smoke is typically very hot and may cause burns on contact . Red phosphorus is less reactive , does not ignite spontaneously , and its smoke does not cause thermal burns - for this reason it is safer to handle , but cannot be used so easily as an incendiary . Aerosol of burning phosphorus particles is an effective obscurant against thermal imaging systems . However , this effect is short - lived . After the phosphorus particles fully burn , the smoke reverts from emission to absorption . While very effective in the visible spectrum , cool phosphorus smoke has only low absorption and scattering in infrared wavelengths . Additives in the smoke that involve this part of the spectrum may be visible to thermal imagers or IR viewers . Dyes . Various signalling purposes require the use of colored smoke . The smoke created is a fine mist of dye particles , generated by burning a mixture of one or more dyes with a low - temperature pyrotechnic composition , usually based on potassium chlorate and lactose ( also known as milk sugar ) . Colored smoke screen is also possible by adding a colored dye into the fog oil mixture . Typical white smoke screen uses titanium dioxide ( or other white pigment ) , but other colors are possible by replacing titanium dioxide with another pigment . When the hot fog oil condenses on contact with air , the pigment particles are suspended along with the oil vapor . Early smoke screen experiments attempted the use of colored pigment , but found that titanium dioxide was the most light scattering particle known and therefore best for use in obscuring troops and naval vessels . Colored smoke became primarily used for signaling rather than obscuring . In today ' s military , smoke grenades are found to be non - cancer causing , unlike the 50 ' s AN - M8 model . Sulfonic acid . The smoke generator on the Medium Mark B tank used sulfonic acid Tactics . Land warfare . Smoke screens are usually used by infantry to conceal their movement in areas of exposure to enemy fire . They can also be used by armoured fighting vehicle s , such as tank s , to conceal a withdrawal . They have regularly been used since earliest times to disorient or drive off attackers . A toxic variant of the smokescreen was used and devised by Frank Arthur Brock who used it during the Zeebrugge Raid on 23 April 1918 , the British Royal Navy ' s attempt to neutralize the key Belgian port of Bruges - Zeebrugge . For the crossing of the Dnieper river in October 1943 , the Red Army laid a smoke screen long . At the Anzio beachhead in 1944 , US Chemical Corps troops maintained a " light haze " smokescreen around the harbour throughout daylight hours , for two months . The density of this screen was adjusted to be sufficient to prevent observation by German forward observers in the surrounding hills , yet not inhibit port operations . In the Vietnam War " Smoke Ships " were introduced as part of a new Air Mobile Concept to protect crew and man on the ground from small arms fire . In 1964 - 65 , the " Smoke Ship " was first employed by the 145th CAB using UH - 1B . Naval warfare . There are a number of early examples of using incendiary weapons at sea , such as Greek fire , stinkpot s , fire ship s , and incendiaries on the decks of turtle ship s , which also had the effect of creating smoke . The naval smoke screen is often said to have been proposed by Sir Thomas Cochrane in 1812 , although Sir Cochrane ' s proposal was as much an asphyxiant as an obscurant . It is not until the early twentieth century that we get clear evidence of deliberate use of large scale naval smokescreens as a major tactic . During the American Civil War , the first smoke screen was used by the " R . E . Lee " , running the blockade and escaping the USS Iroquois ( 1859 ) . The use of smoke screens was common in the naval battles of World War I and World War II .