Step 1: Check Out What Popular Science Had to Say in 1942
"Rather than go without any protection at all, the alert citizen can make gas masks for himself and his family."
The following steps are from a December 1942 Popular Science article on how to make an improvised gas mask.
The following information may help you understand the instructions.
"10/20 mesh" and "4/10 mesh" specifies the grain size of the crushed charcoal.
Sorting grains by size is called "screen classifying". To do it you put a stack of sieves on a sieve shaker with the coarse one on top. To make 10/20 you'd put a sieve with a 10 mesh (ten wires per inch) screen on top of a 20 mesh sieve. You'd pour your crushed charcoal in the top and shake the stack. The 20 mesh sieve would fill up with the good stuff, you'd dump that into your gas mask cartridge.
In other words the charcoal grains they use are between .05" and .25" diameter. I've read that that resistance to breathing while doing strenuous work is the major problem with gas masks. A mask made with such large grains might have very easy air flow.
Soda Lime ( w'pedia ) is calcium carbonate (lime) reacted with aqueous sodium hydroxide (lye). It absorbs carbon dioxide among other things.
Carbon tetrachloride is dry cleaning fluid, very common in those days when synthetic fibers were rare and many people wore clothing such as suits that would be harmed by laundering in water.
Star says "CCl4 note that carbon tetra chloride is carcinogenic like pasta sauce is red, and you probably don't want it in your house or on your hands or anywhere"
The text continues: "This type of mask, designed by Dr.Simon L.Ruskin of New York City, is intended to protect the wearer only against the common, known gases used in chemical warfare. It is useless against smoke, illuminating gas, and carbon monoxide (automobile exhaust).
How such a mask is made is shown in the accompanying photographs. Use a heavy bathing cap, not a thin one. Make joints airtight so that the wearer can breathe only through the canister.
The physical filtering agent in the canister is activated granular charcoal, which can be obtained at drug stores and wholesale drug houses. To test it for activity (the ability to take up and hold gases), place a small amount, such as a tenth of a gram, in the palm of the hand and pour on it five drops of carbon tetrachloride.The charcoal should become warm.
If not, it's unsafe. Either one half 10/20 mesh and one half 4/10 mesh, or the coarser charcoal alone, may be employed.
With it mix one half as much coarse-mesh soda lime (sodium calcium hydrate), also available at drug stores. Pack the canister solidly. No air must enter without passing through the charcoal. Do not forget to seal both ends of the canister with tape or heavy waxed paper. If left unsealed, the charcoal will absorb moisture from the air until it is saturated, and the mask will be useless. Unseal the canister only when the mask is to be put on for protection against gas. Once the mask has been used, the canister must be refilled with fresh charcoal and soda lime. "
