HP discoloration to pink (EO scented)

[szaza]

I've been meaning to post about this a while ago, but never got to it.
For the September challenge I did some HP soaps to attempt a linear swirl. They all had about very similar recipes and EO blends, but somehow the first discolored to pink, the second to light tan and the third stayed a nice creamy white.
This is a picture of their (largely uncolored) bottoms

They all started out white right after cutting, here's a picture of the first soap:
see that white in between? That's now all pink. The discoloration gradually got worse over time, but I think it's stable now.

I don't think the discoloration is caused by the recipe. The first soap (pink one) has only HO sunflower for the soft oil, recipe 2 has HO sunflower and a bit of olive, recipe 3 has mainly olive and a bit of sunflower. Hard oils are the same for the 3 batches (and are also white oils). I've soaped with sunflower a lot and it's the whitest soft oil I have, so I'd be very surprised if that was the culprit.

I thought maybe it could be the EO blend. This is what I used:
1st soap (pink discoloration)
30% Ylang Ylang
23% Lemongrass
20% Ginger
17% Litsea
10% Cinnamon leaf

2nd soap (tan)
35% Ylang Ylang
15% Cinnamon leaf
12.5% Litsea
12.5% Blood Orange
10% Sweet Orange 7fold
10% Patchouli
5% Clove

3rd soap (creamy colored)
35% Ylang Ylang
25% Blood Orange
15% Cinnamon leaf
10% Patchouli
10% Ginger
5% Clove

I don't find any consistent pattern where a certain EO could have caused this discoloration (except maybe litsea, which I have a lot of good experience with, so it's an unlikely candidate)

Last thing I can think of is that I remembered experimenting with trying to get a fluid enough batter. For this purpose I added a lot more yoghurt after cook in the first soap than I normally do. It didn't help and I didn't do it for the 2nd and 3rd soaps. So my current theory is that the pink discoloration in the first soap is from (soy)yoghurt and tan of the second soap is from orange and patchouli EOs, but I still find this idea weird.. does anyone have any ideas what it could be or has anyone seen this before?

 

[Millie]

It might be a reaction between the cinnamon leaf and yogurt? (and lye)
https://www.humblebeeandme.com/cinnamon-oatmeal-soap/
I thought she had a longer post coming to the conclusion that the red was the cinnamon & milk

 

[szaza]

Cool thanks! That could definitely be it! And what an awesome red color she got!!

 

[Millie]

I love that color too! I should put that combo on my to-do list. Now I am craving a spicy milky chai

 

[szaza]

I just ran her EO combo through eocalc, because it seemed quite high in cinnamon and she uses it at 6%. Eocalc marks 33% cinnamon bark 67% lavander red, even at 1%.. I would've loved to make that exact soap, but I guess I'll have to be happy with pink

 

[Millie]

Oh dear, I'll stick with pink too!

 

[Millie]

Your scent recipes look wonderful, I might have to try one of those!!

 

[szaza]

Thanks! I was experimenting with spicy/floral. I'm not very impressed with the first, I find it too sharp. I think the last one is the most balanced, though I quite like the freshness of the second.

Eta: these were HP soaps. This scent would probably accelerate in CP

 

[Millie]

I love spices and florals enough that I have gotten pretty comfortable with soap on a stick

 

[szaza]

I tried the goatmilk+cinnamon theory, using goatmilk for 2 parts of the water in a 3:1 water:lye solution HP soap. (So masterbatch lye and the rest was frozen goat's milk). I split my batter and colored. My eoblend was the following:
10% cinnamon leaf
20% patchouli
70% blood orange.
I mixed the orange+patch into most of the batter, but put the cinnamon into 10% of the uncolored batter in hopes it would turn red over time.
I made this soap on february 24th and this is what it looked like after cutting:

This is what it looks like today, april 7th:

As you can see lighting is a bit different but no red to be seen anywhere.

So unfortunately this red or pink color isn't reproduced with a combo of goat's milk and cinnamon leaf at a safe percentage. I'm out of cinnamon EO, but hope to redo this experiment with (soy)yoghurt (since that's what I used when I got pink, goat's milk was based on the article linked above)

 

[atiz]

I love these HP soaps, I kind of want to try HP now

 

[Millie]

Hmm, the mystery continues. Thanks for the update!

 

[Mobjack Bay]

There have been at least three different unexplained pink soaps posted in recent months. As I recall, in addition to yours, one of them was all coconut oil and one was pink just on the top. So strange...