Test of food colorants in soap – part 2 – after 48 hours
And here is the image from previous post together with the correct answers. Of course, I also add a table with more detailed descriptions:)
A2: Blue mica
A3: Brown: E155 – Brown HT
B1: Yellow: E102- Tartrazine – FD&C Yellow 5 (C.I. 19140)
B2: Blue ultramarine
B3: Red: E124 – Ponceau 4R (C.I. 16255)
C1: Blue: E133 – Brilliant blue FCF (C.I. 42090)
C2: Orange: E110 – FD&C Yellow 6 (C.I. 15985)
C3: Green: E102- Tartrazine – FD&C Yellow 5 (C.I. 19140), E133 – Brilliant blue FCF (C.I. 42090).
Many colors are sensitive to pH and so we can expect them to change as the saponification reaction finishes and pH decreases in time. Please, note, I used 0.12% of color in soap.
To conclude – these food colorants – except for blue, which is more of a violet – get at the end their intended color in soap. One important drawback is that these soaps color very much the water. Of course, there are many ways how to color soap naturally and I will be posting about this (experiments were already done!).