Colour difference in same batch?

[MissPpoodle]

Hi, This is my 3rd batch, used a loaf mould for the bulk, and put the left overs into the single bar moulds. The colour difference is very notable. This is a honey and himilayan salt soap made with Lard, copha and olive oil. My 2nd batch (a different blend) I did between the 2 moulds also, and while there is a colour difference, it is nowhere near as different as this batch. All bars test Ph about 7.25 - 7.5 (both cut loaf and single mould soaps. Is it normal to have such dramatically different colours just from using different moulds?

 

[TheGecko]

Is it normal to have such dramatically different colours just from using different moulds?

Yes...it's called 'gelling' and soap that has gelled has more intense coloring than soap that has not.

During the saponification process, your batter heats up (exothermic reaction); the more batter in the mold, the higher the temperature. And depending on your recipe and your soaping temperature, the exothermic reaction can vary and you end up with a partial gel...the inside of the soap is hotter than the outside...which is why folks will CPOP (put their soap in a pre-heated oven) or wrap their molds in towels and blankets, put it in boxes, use heating pads.

Batter that goes into cavity molds seldom gels because there just isn't enough of it to generate a high heat so you end up with a soap that has a matt appearance.

 

[AliOop]

Your soap looks great, and @TheGecko is right - it is just a difference between gelled and not gelled.

Regarding pH testing, please be aware that testing pH does not tell you whether the soap is lye heavy, and pH strips are very unreliable. Case in point: you cannot have a soap with pH under 8 - it is not chemically possible.

If you'd like to read more about soap pH, this article is a good one.

 

[MissPpoodle]

If you'd like to read more about soap pH, this article is a good one.

Blimey, that is quite a read!

I used some expensive ph test strips I had bought for another reason ages ago, and they have 2 panels and a limited range (4.5 to 9, in .25 increments), but then I did just wet the soap and used that to test, as per instructions. Have just done zap test, and they don't zap, so guessing they can't be too bad.

Just did some Googling, and found another site that seems to say similar things, but goes on to show the results of various test strips, when you do it properly, still can be wrong. So it looks like I will just stick to the zap test from now on, even though it says it can be risky too! https://www.modernsoapmaking.com/blog/how-to-ph-test-handmade-soap

 

[AliOop]

Yes, pH testing isn't as helpful for soapmaking as a lot of YT videos and mommy blogs would have you think. Besides DeeAnna's Soapy Stuff article, the article from Kenna of Modern Soapmaking is a good one, too. As they both explain, to get an accurate reading, you have to dilute a tiny bit of soap (1-10%) in a bunch of distilled water (90-99%). That's part of why yours tested so low, because it was touched to wet soap, rather than a diluted soap solution.

Oh well. Many of us started our soaping journey with pH testing our soap, because many of the mommy blogs recommend doing that. I can't speak for anyone else, but I don't miss all the faffing around with that and was happy learn how unnecessary it is. There are other reliable ways to know if your soap is lye-heavy, such as it being dry, chalky, crumbly, etc.

But tbh, if you've run your recipe through a calculator, included even a modest superfat (2-3% is more than enough), and measured carefully, your soap won't be lye-heavy. So my advice would be to focus on being careful with your process, and your soap will be good.

 

[TheGecko]

Many of us have started with pH testing our soap.

Not me, didn't know we were supposed to. I've never 'zap tested' by soaps either 'cuz you know...got my mouth washed a couple of times as a kid. LOL

I just weigh everything carefully, use a SuperFat and let my soaps cure for six to eight weeks.

 

[AliOop]

@TheGecko I should clarify that I didn’t mean to imply that we’ve recently started doing that. I meant to say, “We started out in the beginning by pH testing …” because that’s what all the mommy blogs recommend. I’ve updated the post to clarify that.

Fortunately it sounds like you were spared that waste of time and money. You were probably listening to better teachers than I was from the start.

 

[TheGecko]

@TheGecko I should clarify that I didn’t mean to imply that we’ve recently started doing that. I meant to say, “We started out in the beginning by pH testing …” because that’s what all the mommy blogs recommend. I’ve updated the post to clarify that.

Fortunately it sounds like you were spared that waste of time and money. You were probably listening to better teachers than I was from the start.

Can't say that I paid a lot of attention to 'mommy blogs' as you call them, there was just too much conflicting information and I took a more analytical and practical approach...hence why I went with a kit and worked on my recipe as opposed to trying to make anything 'fancy'. Not that I'm putting that down...you do you after all, which is what I did. To me it made more sense to learn how to crawl than to try and run and fall flat on my face. Which I still did/do. LOL