SFX FAQs

SFX FAQs

ARTIFICIAL SMOKE

How is Artificial Smoke Produced?

Artificial smoke is produced by heating a chemical above its boiling point within a heat exchanger. The chemical is then vaporised, and it is when the vapour exits the heat exchanger and mixes with the relatively colder atmosphere that rapid condensation of the vapour takes place, resulting in a visible smoke (or technically fog).

It is important that the vaporisation of the chemical within the heat exchanger is complete, otherwise the production of a 'wet' smoke, or a smoke with a very large particle size will result.

Conversely, it is important that the heat exchanger through which the chemical is passed is not operating at too high a temperature, otherwise unpleasant and potentially hazardous pyrolysis products will be formed.

Types of Smoke Generators

There are generally two main types of smoke "gun" as classified by the method of heating the smoke chemical.

1.     For Interior use electric guns are used, which come in various heat capacities, and are designed to perform different jobs. For example the Artem "HAZE" gun will sit in a studio all day trickling out persistent smoke to create an even atmosphere for lighting effects. The Artem "CLOUD" gun would be used for general smoke effects, and can be used "off power" for short periods. The Artem "MINI" is a specialist 12volt smoke gun for confined spaces where mains power is not practical.

2.     For Exterior use where power is not practical, and a large volume of smoke is required, gas powered guns are used. In these circumstances the Artem "Exterior Smoke Gun" may be appropriate, which is a hand held, mobile gun. For larger applications specialist guns are available, usually made to order, which are capable of producing huge quantities of smoke in very short periods of time. Exterior guns tend to use oil based chemical and produce smoke of a larger particle size. They should not be used in interior environments, not least because their gas powered nature could be a fire hazard.

Types of Smoke Chemical

Water Based

The majority of smoke chemicals in use today are generally referred to as 'water based'. This rather vague term describes chemicals which are water miscible, and are in the main, based on glycol's and glycerol.

Water based smokes are dense and white, and the generators that produce them, such as our 'Cloud', can be simple to operate and compact.

Typically two-thirds of the 'Smoke Chemical' is made up of active ingredient, the remaining one-third being purified, de-ionised water.

Different Glycol's produce smokes of differing persistencies, Propylene Glycol generally being the least persistent. Glycerol is by far the most persistent 'water based' smoke.

We would normally recommend that, where dense concentrations of water based smoke are required, that the most persistent smoke possible is produced (using Glycerol rather than glycol). The use of chemicals with high percentages of glycols, whilst producing dense white smoke, is not cost effective, as the smoke disperses so quickly that one is having to produce smoke almost all the time in order to keep up with the rate of breakdown of the smoke.

Glycol based smokes begin to layer noticeably at 35-45C°, Glycerine based smokes at about 50-60C°.

Oil Based

Artem also produce food quality oil based smoke systems. These systems produce a smoke that is far more persistent than the very best of the water based smokes, and so are capable of smoke logging huge volumes with relatively low consumption of smoke chemical. The smoke produced by the "Haze" generator is also extremely resistant to very high temperatures,(for instance where used in conjunction with flame effects) starting to layer at 135 - 180C° dependent on the viscosity of the oil chosen.

How safe is Artificial Smoke?

Artem do not compromise on quality or safety, and have access to a comprehensive technical library of health and safety reports, analyses, independent laboratory tests and particle distribution data. The smoke produced by our systems is amongst the safest available today

General

The "artificial" cosmetic smoke produced by all reputable manufacturers has been subjected to extensive independent tests to ensure that it is non toxic.

However, as cosmetic smoke behaves in a similar way to the toxic smoke produced by a fire, many people coming across cosmetic smoke for the first time are understandably cautious about the material and its safety aspects. The information contained herein should re-assure all concerned with the use of cosmetic smoke as to the material's safety, when used in reputable smoke generators.

Different Chemicals used

There are generally 3 types of smoke produced, using the following chemicals;

Smoke Chemicals (simulants)

Good for;

(a)Propylene Glycol / Purified Water
Steam effects, and less persistent smoke

(b)Glycerine BP / Purified Water
General smoke effects

(c)Food quality white oil
Persistent smoke effects, inc. exterior smoke

Occupational Exposure Levels

The Occupational Exposure Standards (OES) for our simulants are listed below. These standards relate to an 8 hour daily exposure to the chemicals, and whilst dense smoke concentrations exceed these limits, they are of restricted value in assessing the "toxicity" of the smoke, not least because of the comparatively short exposure times experienced in the film industry.

Artem use what are considered to be the safest of the Glycols and the UK's Health and Safety Executive recommend that, should a chemical not be allocated a exposure limit in its own right, the exposure limit for a similar chemical type should be adopted.