Shower Steamer Calculator

The shower steamer recipe: 3:1 by weight

A shower steamer works like a bath bomb, but it sits on the shower floor or a shelf instead of going into a tub. Water from the shower sets off the fizz and releases the scent. The base is 3 parts baking soda to 1 part citric acid by weight, with cornstarch added at about 25% of the citric acid to harden the steamer.

Baking soda : citric acid : cornstarch = 3 : 1 : 0.25
Example: 300 g baking soda + 100 g citric acid + 25 g cornstarch = 425 g dry mix

That is a higher share of baking soda than a bath bomb, which runs at 2:1. The bath bomb calculator covers that recipe.

Menthol and essential oil are optional. The calculator adds them only at the usage rate your supplier gives, and both count toward the batch weight. The binding liquid is left out, since it is spritzed in to consistency. A batch of 12 steamers at 40 g each, before any menthol or essential oil, looks like this:

Menthol vs essential oil

The two do different jobs. Menthol crystals give the cooling vapor that makes a steamer feel strong in the nose. Essential oil carries the scent. You can make steamers with essential oil only and leave the menthol at zero.

The calculator doesn't suggest an amount for either. Enter the usage rate your supplier gives, as a percentage of the batch weight, and it works out the grams. Because the rate is a percentage, the amounts scale with the number and size of the steamers.

Menthol crystals are usually dissolved in a small amount of rubbing alcohol before they go into the dry mix, which spreads them evenly through the batch. That alcohol then counts as part of the binding liquid.

Menthol safety

Menthol is the part of a shower steamer recipe that needs the most care. There is no official usage limit for menthol in shower steamers, and published recipes vary widely, so this calculator doesn't set an amount. Use only the rate your menthol supplier documents for this kind of product. If they don't give one, ask them before you make steamers to sell, and test a steamer yourself before a full batch.

• Not for young children or people with sensitive airways. Menthol vapor is strong. Over-the-counter vapor rubs that contain menthol tell users to consult a doctor before using them on children under 2, or if they have asthma (example label on DailyMed). Give a menthol steamer at least the same caution, and put that warning on your label.
• Handle the crystals with gloves. Menthol irritates skin and eyes at full strength. Keep your hands away from your face while you work, and keep the crystals out of reach of children.
• Sell them for scent, not as a remedy. In the US, a product sold with claims that it relieves congestion or treats a cold is regulated as a drug rather than a cosmetic. Keep labels and listings to scent and experience.

This page is general information, not medical advice. If anyone in the household is an infant or young child, or has asthma or another breathing condition, ask a doctor before using menthol products around them.

Binding: witch hazel or alcohol

The binding liquid holds the dry mix together without setting off much of the reaction. Spritz witch hazel or rubbing alcohol a little at a time, mixing with gloved hands, then squeeze a handful. When it holds together like damp sand and keeps its shape after you open your hand, it is ready. If you hear it fizzing or see it puffing up, it is too wet.

There is no fixed amount, because the right amount changes with the humidity in the room. The same approach works for bath bombs, where witch hazel is the more forgiving of the two.

Pack each mold firmly and let the steamers harden before you unmold them. Let them dry all the way through before packaging, then store them in an airtight container so moisture in the air doesn't start the reaction early.

Why shower steamers crumble or fizz too fast

Crumbling means the mix was too dry, or it wasn't packed firmly enough to hold together once it came out of the mold. Add a little more binding liquid next time and press the mix into the mold hard.

If a steamer fizzes away too quickly, check where it sits. In the direct spray it dissolves fast. On the shower floor or a shelf where it gets splashed rather than soaked, it lasts longer. If the steamers puffed up or cracked in the mold, the mix was too wet and the reaction started early, which leaves less fizz for the shower.

Cost per steamer

The price fields cover the baking soda, citric acid, cornstarch and menthol, priced per pound or per kilogram. Packaging, labels and your time sit on top of that. The candle pricing calculator covers turning a unit cost into a retail price, and the method works the same for steamers.

Frequently Asked Questions

Sources

1. Vapor rub (camphor, menthol, eucalyptus oil) drug label — DailyMed, U.S. National Library of Medicine Children under 2: consult a physician. Consult a physician before use with asthma. Avoid contact with eyes.