At What Temperature Does Soap Melt?


Wouldn’t it be great if you could melt your soap scraps and turn them into something useful? But what temperature do soaps melt anyway? And what will happen if you don’t have the right temperature?

Soap starts melting at 120° F, but some may only start melting at 140° F. The melting point will be different depending on the soap type but also the ingredients present within the soap. Soap will, however, burn if heated above 140°F – 150°F.

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There are a lot of conflicting opinions out there about what temperature is best when melting soap in the microwave. Some people say you should heat it until it’s boiling (250 degrees F), while others insist that you shouldn’t go above 160 degrees F. Don’t heat it enough. Your soap will be crumbly but overheat the soap. Then it will burn and smell bad.

Does soap melt in hot weather?

Soap isn’t likely to melt in hot weather as it is very improbable for it to meet its flashpoint (see below). In hot weather, the most likely problem to appear is some sweating.

So, if you live in a hot and humid area, storing your soaps in a dry and cool place where heat doesn’t affect them is highly recommended. 

What’s most likely to happen to soap in hot weather

While it does not happen all the time, cold process soap is highly vulnerable to dreaded orange spots (DOS), which appear when the oils have become rancid and ruin the quality of your soap.

DOS can appear anytime, from a few months or while it is curing. You will notice that your soap has orange spots and stains all throughout the surface, although sometimes you may see an individual spot.

While hot weather isn’t directly related to DOS, it is a contributing factor. Hot and humid weather may trigger oil rancidity more quickly. Therefore, storing your soap in a cool place with airflow can help preserve them throughout the time.

At what temperature does soap melt?

Different types of soap react differently to heat. Generally speaking, it is safe to say that soap melts at 140ºF, but this, of course, it’s important to take into account different factors, such as the ingredients and the size. This temperature can be imprecise for the soap you currently have at hand.

To give an example, the melting point of melt and pour soap is 120ºF, while others are higher.

On the other hand, synthetic bars or lye soaps are not likely to melt unless you shred them and combine them with water or another liquid, then put them on the stove at low heat – which you would do if you’re trying to rebatch them.

It’s also worth noting that all soap will melt or dissolve if you leave it in water, regardless of the temperature. Due to the differences in structure and size, some soaps will melt quicker than other bars. For instance, if you have soap made from soft oils, it will likely melt more quickly than soaps made from animal fats, like beef tallow.

Will soap melt in a microwave?

Most soaps will melt if you put them in the microwave. It is common to melt soap if you want to rebatch it. However, putting the whole bar will not cause it to melt. Firstly, you need to cut or shred it into small pieces (around half an inch) before heating it.

If you want to melt the soap in the microwave to rebatch it, we recommend you stir it every 20 seconds until the soap has fully melted. This way, you will get an even mixture.

Melting soap is a common practice among soap artisans. If you’re worried about the adverse effects, it may have on your appliance. Soap is not strong enough to damage it. However, your microwave will smell like soap during the following hours.

Will soap melt in the oven?

Soap melts in the oven. This is another common method available to melt the soap and rebatch it. This process works similarly to what you’d do with a microwave – you need to shred your soap in small pieces, use some water, stir the soap and then remove the excess water from the container (at this point, your soap already has enough moisture).

There are different ways of melting soap, including the oven, a microwave, or even a crockpot. Either way, the way of melting it is quite similar and involves shredding your soap into smaller pieces.

Please note that this is how generally is done. Sometimes, your soap may not need extra water because the soap already has all the moisture it needs. If you’re trying to rebatch your soap, it’s highly recommended to analyze the elements it already contains not to end up messing it up later.

How do you melt down old soap?

If you want to melt down old soap or soap scraps and reform them, the process is easy. Here we list all the steps you need to follow to complete this process successfully.

Collect the soap

Gather all the soap scraps you have around. It doesn’t matter what type it is, but we recommend using compatible fragrances for a better effect. It all depends on your preferences. If you don’t want to mix different soap types, remember that you can always separate them.

Shred the soap or break it into small chunks

The next step is to cut your soap into small pieces. This way, it will be easier for it to melt. Once you’re done cutting it, put them on a pot and add water equal to the number of soap scraps you’ve put on the pot. Now, please turn on the burner and keep it at medium heat.

Boil the soap

We want the soap and the water to stick together, and that’s only achievable when they’re hot enough. So, while the soap is still on the burner, try to stir it as often as possible. 

Use a steel colander.

Once you think the water and the soap have mixed well, use a steel colander and pour it. You can use a wooden spoon to “press” the soap and remove all the excess water. You’ll end up with a molten soap mass.

Re-molding the soap

It’s highly recommendable to use small silicone molds, although you can also use glass bowls if you grease them, so the soap doesn’t get stuck after it dries.

Now, put the soap in the mold or the container of your preference. 

Get the soap

All you need to do now is wait until the soap hardens. Once it does, it will be ready to use. You can use it immediately or whenever you find it more convenient.

How do you melt soap without a microwave?

Although the microwave is the safest and easiest option, there are other ways of melting soap:

  • You can use a crackpot. After shredding your soap into smaller pieces, you can add some water, stir for a bit and then remove the excess water. Put the soap in heat again, and stir it until it has melted completely.
  • You can use the oven, too. It is a process similar to what we described in the above paragraph.
  • You can also use the stove’s burners to melt your soap, as we’ve described in the previous section. 

Either way, the microwave is the easiest and quickest option you have available. If you want to melt soap for rebatching, this is the best way to do it.

Can you melt leftover soap?

Yes. Many people melt leftover soap and combine it with other soap scraps to make a new, reusable soap. Combining different soap bars will get different results based on the size, texture, and fragrance. Either way, reusing leftover soap is possible and quite easy.

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