A few questions about hot process/trace

[Homeslice]

Watched a lot of youtube videos, but they always seem to leave me with questions! My only test run is a 100% canola oil soap, which came out quite nice actually, and seemed VERY easy to make.

1. What is the max temp you would heat your oil/lye mixture to make sure it does not burn?

2. If you stay below this maximum temperature, can you still "burn" your soap if you leave it on too long?

3. I used a stick blender and mixed it, and it seemed to blend and get to trace SO FAST. But I kept blending and cooking for awhile, even though it looked done to me in like 10 minutes LOL. Can you ever blend TOO MUCH or TOO SOON?

4. Can you have TOO MUCH of a trace before you take the heat away to let it cool? Is it ever better to have a thinner trace?

5. At what temperature do you typically add your fragrance oils and what not? If a fragrance oil has a flashpoint of 190, is it really safe to add at 185 for example, or better to wait until it is WAY cooler?

Thanks so much!!!

 

[Yooper]

1. It depends on the oils and the temperatures they stay melted at. Coconut oil is liquid at 72F, but tallow will give you a false trace at below 108F.
2. Maybe. Milk will turn brown (burn) at temperatures that are lower than oils, so if using milk I soap cool (even using frozen milk).
3. Yes, you can get such a thick trace that it’s globby and hard to put in the mold.
4. Yes, I often pour at thin trace, especially if I’m adding essential oils or adding colorants/swirls.
5. Sorry, I don’t use fragrance oils and don’t have an answer here.

 

[ChemicalPyros]

I agree with all what Yooper said, but I would like to add a few more notes.

1. What is the max temp you would heat your oil/lye mixture to make sure it does not burn?

I assume you are taking about the hot process temp, not the cold process. There are several parameters to take into account. The main one is the neat phase (or the phase where you should be working in in order to make soap). In order to reach the neat phase you have the oil(s) type and the lye concentration. The oil type is relatively easy, the more the oil contains unsaturated fatty acids the less temperature is required to reach the neat phase. The lye concentration is a bit more tricky, the lower the concentration of lye the lower the temperature needed to reach the neat phase, but the longer the reaction time will be (keep in mind that for most soaps the lower concentration limit for the lye is around 20%).
As long as you are in the neat phase temperature range, you have minimal risk of burning the mixture.

2. If you stay below this maximum temperature, can you still "burn" your soap if you leave it on too long?

Burning, or the oils (fatty acids) will go rancid, is a risk you will always take when heating.
A simple rule to take into account, that when the heat increases 10 degrees Celsius, you reduce the lifespan of the fatty acids by half (i.e.: at 20 degrees Celsius, coconut oil will be good for 3 years, if you store it at 30 degrees Celsius it will go bad after 1.5 years, ..., if you store it at 60 degrees C it will go bad after 68 days, ... if you leave it at 120 degrees Celsius it will be unusable after 1 day).
In conclusion, when heating even if you do not burn the mixture, you might reduce its lifespan considerably, so as a general rule always use the minimum required temperature.

3. I used a stick blender and mixed it, and it seemed to blend and get to trace SO FAST. But I kept blending and cooking for awhile, even though it looked done to me in like 10 minutes LOL. Can you ever blend TOO MUCH or TOO SOON?

It may look done for the naked eye, but the saponification reaction will take some time before being fully complete. The most reliable way to make sure that it is done is by doing the "Zap test". The zap test can be done by taking a small sample with the tip of the spatula and leave it to cooldown for a minute or so, then touching the tongue with it, if you feel a zap, it means that the reaction is still underway, if not it means that the reaction is finished and you only have soap. It may take some trials to master the technique, but it is very reliable and efficient.

4. Can you have TOO MUCH of a trace before you take the heat away to let it cool? Is it ever better to have a thinner trace?

I will assume that TOO MUCH of a trace is the neat phase you are looking for. so no do not turn the heat down before zap testing it.

5. At what temperature do you typically add your fragrance oils and what not? If a fragrance oil has a flashpoint of 190, is it really safe to add at 185 for example, or better to wait until it is WAY cooler?

as a safety rule always reduce at least by 10 degrees from the flash point, but the cooler the better.

 

[Homeslice]

Thank you so much Yooper and ChemicalPyros! So here are a few observations (see how accurate I am) and follow up questions:

1. I think my next batch will be a mainly olive oil, some coconut oil mix, maybe a little canola oil thrown in since I have some left and maybe some shea butter as a super-fat. So no milk or anything else that could burn. If I were to make a general statement, such as "cook it for approximately [1 hour], stirring with stick blender as often as you like, keeping the temperature between [180 and 190] C, and after that [one hour] period adding the shea butter and mixing further, then letting it cool, and before it gets hard adding color and fragrance" and mix before pouring it in the mold, does that general time and temperatures sound ABOUT right? I am definitely going to do the "zap" test you mention throughout the process, and I have pH strips from another life I can use as well, if its waaay above 7 I assume its not done yet. But I'm just wondering if that time and temperature sounds ballpark correct for soap with no other additives (other than color and fragrance after it is cooled significantly).

2. I'll have to read up on the "neat" phase, I've watched a ton of youtube videos on soap making and read a good bit as well, but that is the first time I have seen that mentioned! Thanks!

3. On the water content, is the rule that the less water you use, the harder it will be too cook and shape the soap when its cooked, but the more water you use the longer it should be left to cure?

Thanks!!!

 

[ChemicalPyros]

For:
1. The timing is about right, but always better to check the pH or do the Zap test.
if you like looking at videos, I recommend the Martin de Candre soapmaking workshop (Saponification - @martindecandre) they show their whole process on instagram and frankly I found it very helpful, they use coconut and olive oil for their soaps and of course via hot process.

2. The neat phase is known as the liquid crystal lamellar phase (Neat phase is the name used by the ancient soapmaking masters).
Sorry I do not have any media to recommend, but if you have some time to read there are two books that are very useful:
- Scientific Soap Making - Kevin Dunn
- Soap Manufacturing Technology, 2nd edition - Luis Spitz

If you do not wish to invest in those books, Kevin Dunn has a helpful website.
The second book needs deep understanding of surfactant science in order to be read and understood, so I'll leave it to your convenience.

3. I recommend you start with a 35% lye concentration, and work your way from there to the best temperature and lye concentration that suits you and your setup.