Adjusting Your Bar Soap Formula for Better Solubility

It's great that you're experimenting with making your own bar soap! The issue you're encountering, where the soap lathers well but doesn't dissolve easily, is common and often related to the specific blend of oils used. Oils like palm and coconut contribute to hardness and lather, while others like olive and canola contribute to conditioning and solubility.

The staff's suggestion to add Glycerin is a good one. Glycerin is a humectant, meaning it attracts and retains moisture. When added to bar soap, it helps to soften the bar slightly and improves its solubility, making it dissolve more easily and feel less "hard" or "draggy" on the skin. It can also add a bit of a moisturizing feel.

How to adjust your formula:

• You can try adding Glycerin at a rate of about 1-5% of the total oil weight in your formula. For your 600 ml of oils (which is roughly equivalent to 540-550 grams depending on the specific gravity of the oil blend), this would be approximately 5.4 - 27.5 grams of Glycerin.
• Add the Glycerin to the water phase before mixing with the lye solution.
• Start with a lower percentage (e.g., 2-3%) and see if that improves the solubility. You can adjust in future batches if needed.

Regarding your question about Isododecane, the staff was correct. Isododecane is a lightweight, volatile hydrocarbon used as a solvent and emollient in cosmetics, particularly for products where a dry, non-greasy feel is desired (like some makeup or serums). It evaporates quickly and is not suitable for use in bar soap making, as it would not contribute to the saponification process or improve the soap's solubility; in fact, its evaporation could potentially disrupt the final bar structure.

By adding a small amount of Glycerin, you should find that your bar soap dissolves more readily while still maintaining its good lather.