Hello! I understand what you're up to, because I have been working on the same thing for the past couple of years. That is, trying to find a good soap recipe from oils that are only from the USA. Like you, this means no coconut oil. I can get USA Olive Oil, but it's cost prohibitive, so that's out for me too, as it is you.
So, to the question of will your cited recipe make safe soap. Please post your recipe using consistent measurements of grams for all ingredients, or cite the TotalOilWeight of your recipe.
As for Rapeseed oil (I'm assuming you mean culinary Canola Oil and not industrial Rapeseed oil) going rancid - it seems the answer is "that depends". I've never had a problem with my soaps going rancid that were made with Canola. I have some that are over a year old, made with 50% non-gmo Canola that are as pretty as the day they were born. Others on the forum will tell you to steer clear because in their experience Canola (and other oils too) go rancid in soap in a short amount of time. My thought on these different experiences is that it depends on:
- The quality and freshness of the Canola used.
It's impossible to know your newly purchased oil is actually on the edge of going rancid before you even open it up. In my experience with cooking, both Corn and Canola have pretty short shelf lives in general. I soap with the same Canola and Corn oils I cook with, and I pay attention to lot numbers. If my kitchen corn oil goes "off" quickly, then I know that lot is not fresh and it's all put in the fridge, or "washed" before using in soap. Of course, I don't have this problem with Olive Oil. Also, keep in mind that I'm a hobby soaper, and not one who is using gallons of liquid oil in one batch of soap. Honestly, if I were a production soaper, I might not use Canola and Corn just because of this freshness issue. In the US there are other oils (like soy, cottonseed, rice) with longer shelf lives
- The cleanliness of the soaping environment and tools (Not that I'm any cleaner than the next person, but my soaping area has always been in naturally very clean areas of the house, like the kitchen or in my little dedicated soaping area where nobody else goes)
- The handling of the soap after pouring, and the handling and storing environment during "cure".
- ETA: SuperFat of recipe. I am odd in that I usually use a low SF of 2%
I would offer this unsolicited advice - start with a batch of oils that weigh more in the range of 500g. Also, use a
soap calculator to check any and all recipes.
