I so need to update this thread because a number of the FOs that I haven't reviewed yet survived a long cure and are quite nice soap scents.
This post is only an updated description of the process I use to make the testers:
I try to keep my testing as similar to my regular soaping process as much as possible. I don’t have a single recipe that I use repeatedly. I tend to use 50% solid oils including 5 to 10% real butters and 50% liquid. I do use a bit more linoleic acid in the tester mix to get an indication of DOS formation with extended cure. So far, fragrances have been the only contributor to DOS. My test recipe has 30% tallow, 15% coconut, 5% Mango butter, 5% castor, 10% canola, 10% Apricot Kernel, and the rest is rice bran or high oleic sunflower oil. I add 1%salt, 2%sugar, 1% EDTA or citrate, 1% sodium lactate or some vinegar just like my regular soaps. Vinegar is better for small testers.
-I aliquot the FOs few days in advance in small 2 ml tubes (~1.5g) or in 7 ml (~6g) tubes (picture attached). It is just a convenience because I pour a lot of testers in a single session. I can open the tubes and dump the content in the batter and stir. It minimizes the length of time I have to smell the FOs. It would be messier and slower if I had to open bottles and measure a small aliquot. Sometimes I add clay especially when I think the fragrance is delicate. I wash the tubes and reuse them repeatedly. This amount of FO adds up to 5 to 6% of batter weight. This is always my starting point. I can use less on the next round if needs be.
-The 2 ml are added to 30 to 40 g of batter. The 7 ml goes into 120 to 150g. I used to weigh the batter into the small containers but now I just eyeball it. I used to pour mostly the large testers but I mostly pour the small ones now. The FOs that survive the cp process (at least to my nose) can easily be identified from the small tester. Same for the wet test. My suggestion is to start with no more than 60g of batter which will need half of the 7ml tube in FO. Otherwise, you’ll end up with a lot of soaps to deal with (rebatch, trash, find somebody who likes the scent).
-For containers, I use the small waxed paper cups, small 2oz plastic condiment containers or yogurt cups (picture). I have a bunch of baby silicone spoons to stir the fragrance. The paper cups are convenient because I don’t have to wash them and I don’t feel too bad dumping them in the garbage. The plastic containers I wash (a real pain) and reuse. Otherwise, I can’t justify using them. If you use the paper cups, you need a thicker trace (pudding) because the wax will react with the lye. All the containers can be CPOPed if that is a normal part of your process.
-I mix my batter mostly by hand and let the reaction proceed while I set up, with occasional stirring. I usually have all the containers numbered and in order and the FOs lined up in a rack. When the batter is ready, I pour batter into 5 to 10 containers, dump the FOs by # into the batter then stir. I repeat until all the testers are poured. I always pour a naked tester to have it for comparison. I group the testers as close together as I can to benefit from the exothermic reaction. Some of them will overheat, relatively speaking. You can identify problematic FOs if you check on the testers during the first few hours after the pour just from the higher temperature they reach.
-You can get an indication if a fragrance is going to accelerate or rice from the small tester even though the reaction is slower in a small vessel. Some of the testers become quite hard before you finish the pour and the surface is not perfectly smooth. You can also get an indication of ash as you can see in the tester picture below.
-I’ve done CPOP and I’ve left the testers covered with towels in a warm place. You can unmold faster when CPOP but both work. To get an idea of how the FO will behave in your soaps, follow your normal process.
-Numbers (and excel) are your friend when you do a lot of testing. You can’t keep track otherwise.
You can see the poured samples and the unmolded testers in the pictures below. I keep my testers in the basement, temp and humidity controlled. I leave them alone for at least 3 months, sometimes longer before I try them. Pouring is the easy part. The hard part is finding enough time to smell few testers repeatedly and in different order on different days until you have an idea of what the true scent profile is like. It helps to have the FO spotted on a small piece of absorbent paper for comparison.
Let me know if I can answer any questions.
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