Improving Foaming Soap Tablet Formulation: Binding, Foaming, and Effervescence

Hello! It's great that you're experimenting with making foaming hand soap tablets. This is a fun project, but effervescent tablets can be tricky due to moisture sensitivity. Let's look at the issues you're facing and how you might adjust your formulation and process.

Your ingredients include:

• Surfactants: Cocoyl Glutamic Acid and Foaming Tea - these are responsible for cleaning and creating foam.
• Effervescent System: Citric Acid and Sodium Bicarbonate - these react in water to produce fizz (CO2) and help the tablet dissolve.
• Binder: Fractionated Coconut Oil - used to hold the powder together.
• Filler/Binder: Corn Starch - can absorb moisture and help bind.

Here are some thoughts on your issues:

1. Tablet Binding and Dryness:

• Moisture is the Enemy: Effervescent tablets are highly sensitive to moisture. Any moisture during mixing, pressing, or storage will cause the Citric Acid and Sodium Bicarbonate to react prematurely, leading to soft, crumbly, or swollen tablets that don't fizz properly later.
• Binder Amount: While Fractionated Coconut Oil can act as a binder, using too much can make the tablet feel oily and hinder proper drying and dissolution. Try using the minimum amount necessary to get the powder to hold together when pressed.
• Process & Storage: Ensure all your dry ingredients are completely dry. Work in a low-humidity environment if possible. After pressing, ensure the tablets are thoroughly dried (perhaps in a low-temperature oven or with a desiccant, if safe for the ingredients) before storing them immediately in an airtight container away from humidity.

2. Cleaning and Foaming:

• Surfactant Concentration: The "slippery water" feeling and lack of foam suggest that the concentration of your surfactants (Cocoyl Glutamic Acid and Foaming Tea) in the final dissolved solution might be too low relative to the other ingredients.
• Binder Interference: Oils, like Fractionated Coconut Oil, can sometimes suppress foam. If you used too much oil, this could be contributing to the lack of foam.
• Suggestion: Try increasing the proportion of Cocoyl Glutamic Acid and Foaming Tea in your dry mix relative to the Citric Acid, Sodium Bicarbonate, Corn Starch, and the binder oil.

3. Effervescence and Dissolution:

• Acid/Base Ratio: The fizzing comes from the reaction between Citric Acid and Sodium Bicarbonate. Ensure you are using an appropriate ratio. A common starting point is roughly 1 part Citric Acid to 2 parts Sodium Bicarbonate by weight, but this can be adjusted for desired fizz rate.
• Binder Effect: As mentioned, the binder (oil) can coat the particles and slow down the reaction and dissolution rate. Reducing the amount of oil should help the tablet dissolve and fizz faster.
• Particle Size: While not something you mentioned controlling, the particle size of your powders affects reaction speed. Finer powders react faster but are less stable to moisture.
• Water Temperature: Using warmer water will significantly speed up the effervescent reaction and dissolution compared to cold water.

Process Tips:

• Ensure all powders are bone dry.
• Mix all dry ingredients (surfactants, citric acid, sodium bicarbonate, corn starch) thoroughly before adding the oil.
• Add the Fractionated Coconut Oil very slowly, mixing constantly, until the mixture just holds together when squeezed in your hand (like damp sand). Do not add too much.
• Press the tablets firmly.
• Dry the tablets completely and store them immediately in an airtight container.

By adjusting the ratios of your ingredients, particularly increasing the surfactants and potentially decreasing the oil, and by being very careful about moisture throughout the process and storage, you should be able to improve the performance of your foaming hand soap tablets.

Good luck with your next attempt!