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I'm photographing small objects (3 to 5 cm height glass jars) inside a laboratory and want to add a little bit of smoke for extra context.

Because I'm inside a lab it's not suitable to use smelly smoke like cigarette or incense.

Is there a DIY way of producing innocuous smoke (or water vapor) suitable for this situation (also in terms of duration and quantity)?

Reference images:

photo by David Brandon Geeting

photo by David Brandon Geeting

photo by David Brandon Geeting

Thanks

Most commercial photographers who use smoke a lot buy a commercially made "fog machine" that converts a fluid into dense vapor. The fluid is primarily made of water and glycerin. The machine simply heats the fluid in a semi enclosed space, producing the fog/smoke.

You can create such a machine yourself easily. You just need something that can hold the fluid above a heat source. An enclosed vessel with a hole in the top does better than a vessel with an fully open top, as it allows the vapor to collect above the fluid before escaping.

This DIY YouTube video shows how to cut apart an aluminum soft drink can to make a simple fog machine heated by a candle placed underneath it. Basically, the can is cut in half. The lower part is inverted with the concave "dimple" on the bottom holding the fluid and most of the side is cut away to allow a small candle to have a source of fresh air. The top half of the can is then placed on top of the inverted bottom half with the small hole in the top open to allow the fog to escape.

This DIY instruction uses a mini pie tin with the inverted top cut off a two-liter soda bottle taped to the top of the pie tin, which is suspended above a large candle. This YouTube video makes a similar device.

The trick with any of these DIY devices is to only use a small bit of fluid, say a teaspoon to a tablespoon (5-15 ml), at a time. You'll be surprised at just how much "fog" will be made using such a small amount of glycerin and water!

Instead of buying commercially made "fog juice", you can make your own with distilled water and glycerin. Your water must be pure and free of chemicals such as those often added to tap water, like chlorine, fluoride, and various softening agents. Vegetable glycerin will work if no chemical grade glycerin is available. I've seen ratios of anywhere from three parts water to one part glycerin (25% glycerin) to a glycerin:water ratio of 7:3 (70% glycerin). Most sources go with about 25-35% glycerin content.

Another method of producing "smoke" is to dump some chips of dry ice (frozen CO₂) in water (hot water will produce more "smoke" more quickly, but dry ice is cold enough that the water usually won't stay hot very long).

About the only danger I can think of is that the dry ice is cold enough you normally want to wear gloves when you handle it. In gaseous form, CO₂ is fairly harmless unless you release a huge amount of it in a space with extremely poor ventilation, so you end up with too little oxygen to breathe properly. You'll notice that very quickly though. For example, when you hold your breath for too long, the overwhelming urge to breathe is due to your body sensing an excess of CO₂, not a lack of oxygen.

If you're in an environment with so much nitrogen or helium that you don't have oxygen to breathe, you can pass out or die without knowing you were short of oxygen--but if you managed to release a dangerous amount of CO₂ you'd know it essentially immediately (but this would still be unlikely unless you were in a room with extremely poor air circulation).

One option is to use an E-cigarette.

I've used it to add smoke in the background of people, when complemented by black lighting the smoke gets really visible.

You'll want to use preferably high VG liquid. It depends a bit on whether the place allows it or not. If you buy a 100% VG (vegetable glycerin) base, and you add no aroma and no nicotine, you'll end up with a fairly innocent smoke machine.

You'll need to do it quick or have someone do it for you, but it's really cheap.

There are several commercial products available for this at a reasonably low cost.

1) Smoke tablets/pallets. Available in several colors, around 5-10 dollar per pack of 3 to 5.

2) Smoke in a spray can. Showtec Magican Hazecan. Instant smoke in a can for about 15 dollar.

3) A commercial smoke machine. Available well under 50 dollar.

And do not discard adding smoke on postproduction as a new layer, as you want to add it as "extra context".

Use some of these: https://www.google.com/search?q=smoke+brushes

Also, this would be the least intrusive method of adding smoke into a lab situation. Every other product can drop some contaminants into the mix.

From the photography point of view, I do not want to discourage you, but taking photos of smoke is challenging because the ratio of the light needed to view a decent smoke and the ratio to illuminate your scene can be dramatically different.

It is easier if you take photos on a dark background and aiming a direct light beam from one side into the smoke. But if the smoke is interacting with a light object you probably will not see it.

I would practice taking some pictures outside of the lab, in your home. Use cigarette or incense and solve the illumination problem before making a fog machine.

An external flash combined with some masks made of cardboard is useful to aim a good amount of light into the smoke and not spilling light into the main subject.

As you can see in the pictures you posted, the light is direct light very close to the table.

The scale of the waves is important. This depends on the airflows around the smoke.

One more thing, define if you need "smoke" which normally goes upwards, or fog, that normally stays at floor level.