Why Bar Soap Turns to Mush in Summer (And How to Make Yours Last)

The bar that lasted all winter is suddenly a soft little puddle on the edge of the sink, and it's only June. If your handmade soap seems to be disappearing faster now that it's hot out, you're not imagining it, and the soap isn't defective. It's doing what good soap does in the summer. Here's what's going on, and how to get a lot more life out of every bar.

Why bar soap softens in humid weather

Real handmade soap is full of glycerin. Glycerin is a humectant, which means it pulls moisture out of the air and holds onto it. On your skin that's the point, and it's part of why a cold process bar feels different from a drugstore bar. In a steamy bathroom in July, it's also why the bar goes soft. The glycerin is drinking up all that humidity.

Many mass-market bars don't have this problem because they contain less glycerin. Handmade soap keeps it. The trade-off is that it's a little needier about where it sits.

It's not going bad

Before anyone panics: a soft bar isn't a spoiled bar. The soap is fine. What's happening is on the outside, not the inside. The surface softens because it's sitting in humid air, or worse, in a little pool of water on the sink. A bar left in a puddle will dissolve. That puddle is the number one reason a bar vanishes in a month instead of lasting two or three.

How to make bar soap last longer

The fix is almost entirely about drying. Soap that gets to dry out between uses lasts much longer than soap that stays wet. A few things that make a real difference:

• Give it somewhere to drain. A soap dish with ridges or slats, or a soap saver bag on a hook, lets water run off instead of pooling under the bar. This one change does more than all the others combined.
• Keep it out of the direct spray. If your bar sits on the tub ledge catching shower water the whole time you're in there, it never gets a chance to firm back up. Move it to the far end, or take it out with you.
• Rotate two bars and alternate days. Letting each bar fully dry between uses can stretch them well past what you'd get using one straight through.
• Don't stockpile extras in the bathroom. The backup bars in the cabinet are softening too, just more slowly. Keep them somewhere cool, dry and airy, like a linen closet or a drawer, and they'll be in better shape when you reach for them.
• Use a soap saver bag for the last sliver. It lifts the bar off the surface so it drains, and when the bar wears down to a thin piece, the bag turns it into a lather pouch so you use every bit.

None of this takes anything fancy. A handmade soap bar on a draining wooden dish, kept out of the puddle, will outlast the same bar left flat on a wet sink by weeks.

If your soap's been melting away faster than it should, it isn't the soap and it isn't you. It's the humidity and the puddle. Give the bar a chance to dry out between showers and it will stick around much longer.