Hot Process Lye Bars

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I’m Robin Wilson, one of the soap making instructors at Ploughshare. I’ve been making soap for just over 20 years, and three or four years ago, I, along with a friend, started the Dausy Artisan line of specialty soaps and skin care products. In this video we’re going to cover the basics of soap making. As you gain experience, you can branch out in different colors, different scents, different shapes, and really have a lot of fun with it.

Soap making does use, lye, which is a necessary part of soap making. But it’s caustic. So we need to be careful. You do not be afraid of it, but we do need to have a healthy respect for it. So we’re going to want to use some safety equipment. We want to wear gloves and then a mass. As you mix the lye, the fumes are released. You want to wear a mask in order to protect your lungs from the fumes. And then we recommend that you wear goggles the whole time that you have the lye out, until you’re done pouring your soap. So I’m going to go ahead and put mine on.

There are a couple of different basic ways to make soap, the hot or traditional cooked process, and then the cold process. Right now we’re going to do the hot. I think the hot process is simpler. The beauty of it is, you throw everything in the pot. You cook it until it’s soap. It’s very obviously soap when you’re done.

So the first thing I always do is get all my ingredients out, assemble everything, prepare my mold, get everything ready. Today we’re going to use coconut oil. We’re going to use olive oil, beef tallow. You always want to have vinegar on hand to neutralize any lye spills. Of course we have our lye, and then water. And scent, we’re going to use spearmint in this batch.

Soap making really doesn’t require that much equipment. You probably even have a lot of it at home already– an appropriate size pot, depending on the size batch you’re going to make, and a long enough spoon that you can stir without getting your fingers involved. Measuring cups, you’re going to want a digital scale, too. It’s more accurate, really, to weigh your ingredients than go by volume. And the other thing that you’re going to want is something to pour your soap into. In this case, we’re going to use a 14 by 20 wood mold. The sides come off, which is going to make it easier, tomorrow, to cut it.

OK, so the process of soap making really is very simple. You just take various oils or fats and combine them with lye water. And that chemical process is called saponification.

When you makes soap, you’re making two things. You’re making soap, and you’re making a glycerin. Commercially, most soap makers pull the glycerin out, which leaves you with a dryer, chalkier soap, but glycerin is very lucrative. They use it for heart medicine, explosives, toothpaste, lotions.

OK, so I’m just going to do a little explanation of really what’s going on in the pot as we cook. So the three main components of soap are water, which is H2O, so here’s our little water molecules, two hydrogen and an oxygen; the oils or fats which are triglycerides, so we have three long fatty acid chains bound together by a glycerin backbone; and then our lye molecules, of which there are billions in this pot. And what happens is that, as it cooks and starts to churn around together, the lye molecules release the glycerin off of those long fatty acid chains, which converts them into soap molecules.

The way soap works, people occasionally ask, what is soap doing in your laundry? How does it clean? And what happens is, once you’ve got this little soap molecule, one end is hydrophilic. It loves water. And one is hydrophobic. It’s looking for anything else to hang onto. So what you do, when you have dirty pots or whatever, and you scrub, you have to use some swishing action in your laundry or scrubbing action in your pot. What it’s doing is, it’s knocking everything that you want to clean out– the soap grabs it. One end is hanging onto water, and one end is hanging onto anything else. And so it really suspends it. What soap is really doing is breaking the surface tension between your water molecules and suspending the dirt until you rinse it away. So that was a very simple version of what simplification actually is.

OK, so the next step is to dissolve our lye into the water. When we do that, it’s going to cause a chemical reaction that’s going to release a lot of lye fumes. Because the lye is caustic, we recommend doing that outdoors or in a well-ventilated area, just for safety’s sake, really.

I usually, when I very first start to make soap, I get all my ingredients out. The first thing I do is to my tallow in a pot to water bath it. And then we’ll go outside and mix our lye.

OK, so here we are outside to blend our lye. Rachel’s going to help me do this, so I can talk. We do need to lye.

Lye is a necessary ingredient in soap making. And it’s dangerous. It’s caustic. So that’s why we’re wearing our safety gear. In order to protect from the caustic fumes of the lye, we’re wearing goggles, indirect vent goggles, in order to protect our eyes, and then masks to protect from the fumes.

OK, so we’re starting with a gallon of spring water. It is crucial that we use water that doesn’t have any minerals in it, or any sodium added. That’ll hinder the saponification process later on. It’s more accurate to do your measuring by weight. In this case, we’re headed for 12 ounces of lye.

OK, you want to start your water moving slowly as you pour your lye in. You never want to pour your lye in to where it falls in a clump. It’s hard to dissolve. It can be dangerous. As you try to dissolve it, it can splash on you.

You’ll notice the water’s getting foggy as the chemical reaction starts to occur. You know that your lye is dissolved when the water goes clear again. The other thing we do, we always start with cool water. When the lye hits it, the chemical reaction spikes it up to about 140.

OK, the other thing is, you’ll notice we have a bottle of vinegar sitting here. Lye is, obviously, an extreme alkaline. And if you get it on you, vinegar is acidic, you would your vinegar to neutralize the lye on your skin.

OK, so you’ll see it’s just been a couple of minutes that Rachel’s been stirring. And it’s totally clear again. Hot process soap uses proportionately more water. So it’s a weaker lye solution. So you’ll see now that we’ve stirred it a couple of minutes, it’s completely clear again. A stronger solution never goes fully clear. Like, in our cold process later on, it’s going to stay a little bit foggy. OK, so now that we have our lye water completely prepared, we’re going to move back inside to cook it on the stove.

OK, so it’s been about 20 minutes and it’s still not quite melted. You can see there’s still a solid chunk in there. So we’re going to leave it in for a few more minutes, until it’s totally liquid.

OK, so it looks like our tallow’s ready. I try to store mine in the quantity we’re going to actually use. So today we are using eight cups of tallow. See the suds? It’s starting. We’re also going to use olive today. Olive oil is very moisturizing, very good for your skin. Readily absorbs in. We’re going to use 2 and 1/2 cups.

And again, one of the good things about the hot process is, you just pour everything directly into your lye water. I’ve added the tallow. That was the olive. And now we’re going to do coconut.

Now coconut oil is solid at room temperature. So we water bath it, so that we can incorporate it in a liquid form. We’re going to use two cups of coconut. Coconut really contributes a lot to the lather of your soap. But it’s slightly drying, which, if you have oily skin, is great. If you have dry skin, you might want to use a little bit less. OK, so now that we have all ingredients in here, we’re going to move to the stove and start cooking it.

And this should take about 45 minutes to an hour before the saponification process is complete. So when we first put it on, I put it on pretty high to go ahead and start to bring it to a simmer. Once it starts to simmer, I’ll turn it down. It should take only 5 or 10 minutes, really.

When you first pour your oils and fats into the lye water, because it’s cooler, it sets up and gets thick again, a little bit. We melted down our fat. But when it hit that cool, it got thick. Now that it’s been on the stove for a couple minutes, you’ll see those fats have melted down again. And if you look down in here, what happens is, oil and water don’t mix. So your oils are floating on top, and the lye water’s underneath. And you can see there’s a layer right in between the two where it’s starting to curdle. Those little soap molecules are starting to form.

And at this stage, until it starts to simmer, it’s good to stir it because otherwise, the lyes and the oils aren’t going to mix. They’re never going to see each other. So you kind of want to keep it moving for a little bit. Once it starts to simmer, the boiling action is going to stir it for you, really– although you want to stay nearby and keep an eye on it.

OK, so you always want to have your mold prepared before your soap is ready. These are wooden ones that we make here, and sell, that collapse. The sides come off, which makes it easier to cut tomorrow. I’m going to first the down a layer of plastic, which is going to protect the wood and also make it easier to take the soap off the board.

OK, so once we have it lined with a layer of plastic, we’re going to put the sides on. You can wrap these in saran wrap, or you can use a trash bag, really, for both of these. I have mine permanently lined with packing tape so that you don’t have to do it each time. And then the tray itself just fits down in the notches on the board. And it’s held together with these rods.

OK, so here it is ready to pour our soap into. And then remember, even as you’re preparing your essential oils, or your mold, remember to keep checking your soap, stay right here with it, and keep an eye on it. And stirring it. Stirring it is going to speed the whole process up.

OK, you can see now, this has been cooking for a few minutes. And see, it’s starting to get bubbles in it, which, of course, when you put soap in water, it sets. And there’s lots of water in there. OK, so you can see, when you stir it, there’s starting to be a few little strands of soap down in there, a little bit of a stringy look.

OK, so you can see it’s starting to simmer. So I’ve turned it down a little bit. See, it’s starting to get this layer of creamy foam on top, which is soap. There’s still, as you stir it, you can see underneath, there’s still lots of oil and water just free floating around under there. You can see, with this cook process especially, the steam coming out. And there are lye molecules in that. If you have sensitive lungs at all, you might want to go ahead and wear your mask throughout the cooking process.

OK, so you can see now, as we stir, it’s getting thicker. But look at the spoon. OK, you can see on the spoon that there’s creamy little soap blobs there, but there’s still water. It still breaks in between. When the soap is ready, it’s going to be one solid sheet. So it’s crucial at this stage to see what not ready really looks like.

As long as there’s still lye water floating underneath, when you pull your spoon up, you’re going to have little free-running streams of lye water coming off your spoon. So you can

see here, it’s starting to sheet off. See how it holds together a little bit before it falls? But there’s still drips of water, that’s lye water, coming off. So again, this is a sign that it’s not ready. When it is ready, it’s going to be one solid sheet. As long as you still see it breaking on the back of the spoon, and there’s drips of water coming off, it’s still not ready.

So you can see now, if you look along the edge of the pot, as I stir it, the whole mass is kind of spinning in the pot because there is still free lye water. Once it’s completely done, it’ll stick on the side. You won’t have that freedom of movement. I’m going to scent this batch spearmint.

You really do not have to scent your soap. If it’s made with fresh ingredients, it’s going to smell good anyway. But you can use either essential or fragrance oils. Just look, when you start looking at different fragrances, especially, there’s different grades. And you don’t want to use anything alcohol-based. It’ll evaporate out as soon as it hits the heat. And you want to make sure that you’re using something skin grade or soap grade, not made for potpourri.

OK, so I’m just going to point out a few ways to tell when your soap really is done. See how it’s, really, it’s thick and creamy all the way through, and when you pull your spoon out, see how it comes off in a sheet? And then this is my favorite part. See those little strings? See? That’s how we know that it’s ready.

OK, so now that it’s ready, we’re going to move it back to the table and let it cool down a little bit before we add the scent. See if that’s a good one, a really good one. So you can see how it’s still steaming a little bit. Ideally, you would let it cool to where it was no longer steaming before you added your scent. It usually should be cool enough to add to scent within about five minutes. So if you just stir it around a little bit, kind of keep it moving.

OK, so you can see it’s not steaming quite as much. It’s getting a little bit thicker, a little creamier. And I’m going to go ahead and add the scent. For this size batch, in a way, the quantity you use depends on the strength of the oil. I’m using mint, which is comparatively strong, so I’m going to use four or five ounces. Of citrus, you might go up more towards six.

And once it’s in, you want to make sure it really is very well incorporated. You can see right now, see there’s a kind of some swirls through of pockets of oil And you want to make sure all those are gone, otherwise you’ll have streaks in your finished bar. You’ll also notice the mist turning it slightly tan. Different oils do have an effect on the color.

OK, so now that we have the scent well incorporated, we’re going to go ahead and pour it into the prepared mold. So you can use a rubber spatula to get all of it out. So now that we have it poured, we need to let it sit and harden overnight. By tomorrow, it should be the consistency of fudge, so it will be firm enough that we can cut it and move it on to drying racks. OK, so this is the fun part. When you run your water in, you’ll notice that the suds start in because it is actually soap.

So this is hot process spearmint soap we made yesterday. We should remember, it was thin when we poured it, and now it’s set up. It’s solid. So the first thing we’re going to do is take the sides off the mold. And then it’s easier to get the sides off if you run a knife around.

Hot process actually shrinks a little bit even before you cut it. So it’s pretty easy to get out. OK, you can go ahead and trim these edges if you want. It’s easier than breaking them off later.

The traditional cooked or hot soap shrinks a lot. It has, proportionally, more water in it. So we’re going to cut the bars. They’re going to look to be rather large when we cut them, but they’re going to shrink. So this is only going to make 28 bars. So we’re going to have hour down one side and seven down the other. So we’re going to cut it at two and seven eighths.

The easiest way to make sure that you have evenly spaced bars is to go through and make notches along each side that you’re going to use as guidelines later on. In this case, we’re cutting at 2 and 7/8. OK, this shorter edge is 14 inches, and we’re going to cut it into four bars. So I’m going to mark it at 3 and 1/2 inches. OK, so now we have notches along all four edges. And I’m going to use the side rail of the mold to score a real shallow line along the top that I’m going to follow as I cut.

So once you have it scored into your 28 bars, we’re going to take just a butcher knife and cut it. Now hot process soap shrinks a lot. And if you cut it crooked, it’s going to exaggerate as it dries. So you want to keep your cuts as straight as you can.

And if you’re going to make a lot of soap, you might want to pick up one of these. Our metal smiths make them. They are stainless steel blades that make the cutting process much faster.

So once we have all of our bars cut, we’re going to transfer them to a rack. So your hot process soap needs to cure at least six to eight weeks. A lot of water is going to evaporate out. If you don’t allow it to cure for that six to eight weeks, your soap’s not going to later.

You’ll notice I’m flipping it over. The top has already been exposed to the air for 24 hours. So now the bottom needs to dry. And you want to leave enough space in between that they can have some air circulation.

It is important to use either a stainless steel or plastic coated wire rack. Your soap will still react with aluminum. OK, so then we’ll put the rest of these on another rack. And then you want to set your soap to cure in a cool, dry area that’s got good air circulation. It is going to shrink quite a lot, the hot process does. So you’ll want to rotate them every couple of days as they shrink. And you’ll notice, I said earlier, these bars do look kind of big. In two months, they’re going to be that size. They’re going to lose a lot of volume and a lot of water. So they will be a nice, average bar size when we’re done with them.