In case you might have been living under a rock for the past month or so, I've got a news bulletin for you.
Like, really hot.
Not that I'm surprised, considering that it's summer in North Carolina and all. But dang, for whatever reason it seems worse than usual this year. It's been consistently in the upper 90's for several weeks now, with no real relief in sight. And pffft to you Arizona people, where there is no humidity. Over here we have swamp air in addition to heat. So it feels like we are living more or less on the surface of the sun.
But what does heat do to soaps? Or to other bath and body products, for that matter. Let's take a look.
Cold Process Soap
Unless you leave it out for an extended period of time, cold process soap should be ok in the heat. I don't recommend leaving a bar under the seat of your hot car for a week to find out however! But mailing and receiving soap in the mail, for example, should cause minimal, if any, damage. Cold process soaps have the potential to heat up to 150 degrees or more during the gel phase, so normal high temperatures of a enclosed car or mail truck should be ok in the short term.
Melt and Pour (Glycerin) Soap
While the melting point of these types of soap will change depending on precisely which type it is, I've generally experienced these soaps melting at around an average of 120 degrees. This means that glycerin soaps should not be left in the sun for very long. Especially in closed cars, where temperatures can easily exceed 120-130 degrees. If the soaps are tightly wrapped, they will most likely be ok after they cool back down. Unfortunately, they may lose much of their design due to the possible softening or melting. They may also form "glycerin dew," which appears when the glycerin in the soap draws moisture from the air.
Excessive heat can cause problems for emulsified cream-type lotions. In some cases, heat may cause the emulsion that holds the lotion together to fall apart. This leads to the oils and water in the lotion separating. This can't really be fixed, so the lotion would have to be thrown away. If the lotion gets excessively overheated, there is also the possibility that the preservative used in the lotion could be compromised. This depends on which preservative was used, since different ones have different heat sensitivities. Once again, in this situation, the lotion would need to be thrown away to prevent possible microbial contamination.
Peppermint Lip Butter
In the presences of heat, lip butters will melt. I design my lip butters specifically to be soft and spreadable when used either "cold" or slightly warmed from body heat (such as when carried in a pocket). When the ambient temperature rises above average body heat, the lip butter will melt. However, because there are no preservatives or emulsifiers, it will be perfectly fine to use once it solidifies.
Lotion bars are very similar in composition to lip butters. They are designed to melt upon contact with the skin, which means they have a pretty low melting point. When these temperatures are exceeded, lotion bars will also melt. Like lip butters, they will be fine to use once solid again. If there was a molded design, this may be gone, but they are perfectly fine to use.
Solid Bubble Bath Bars
As far as I have been able to ascertain, heat has no real effect on solid bubble bath bars. Most of the ingredients are not heat sensitive, so the excess heat of being outside (for example, in a mail delivery truck) should make no different to these. The only thing that I can think of is that excessive exposure to humidity might possibly cause the bubble bars to become sticky, but this has no effect on the performance of the bubbles. I individually wrap each bar, so hopefully that isn't too much of a factor.
Depending on the specific oils or butters used in the making of a bath bomb, they may become slightly more fragile when exposed to heat. The good news is that the heat doesn't alter the bath bomb's effectiveness at all, even if it breaks in transit. Simply dump the contents into the bathtub and watch them fizz away. It might not have arrived in perfect condition, but it will still work just fine.
Most of these items will be ok after cooling down a little. However, because of the heat, I do pull some of my products during the summer months. Things like Lip Butters and Lotion Bars will make their return in September, once the weather has cooled down. I strive to bring quality products to everyone, and part of that is having them arrive in perfect condition whenever possible. To assist in this, I have decided that shipping these items during the hot summer months is not worth it. Look for them to make their return in a couple months!