Rainbow Cake Soap Fun

Days ago I saw this link on Facebook about making a rainbow cake loaf, it got me very excited!  Normal people see cake, I see soap!

 

This is a very time consuming project, it needs to be made in multiple stages, actually very similar to baking a cake and then decorate it.  To start, I went to home improvement store and bought a sheet of plastic corrugated panel, it's lightweight but non stick and not that hard to cut.  I made myself a cheap mold so I can make a skinny loaf of soap.

I used banana blended in coconut milk to make the "cake."  The speckles from banana is perfect for imitating an actual cake don't you think?

The next day I unmolded the soap and made some whipped soap for icing to cover all 5 sides.  Curious about what whipped soap is?!  Well, I got it covered, see this post about making whipped soap: How to Make Whipped Soap

The reason I used whipped soap for icing is so I would have plenty of play time to get it all smooth and pretty.  And whipped soap texture is the closest to the real texture of cake icing or whipped cream.  This is the time consuming part.  After slapping on the whipped soap with a knife I started using a silicone scraper to smooth all sides out back and forwards many passes.

The last stage is the color drizzles.  This is the part that went crazy on me.  Splitting a very small batch of soap into 7 colors is not a good idea.  I was not able to keep the soap batter fluid enough, it was more like icing than syrup.  Instead of drizzling on the "cake" top, I had to improvise and scoop each color soap into a sheet of saran wrap each, scrunched up all sides, poke a tiny hole at the center and squeeze it like a pipping bag.

They look like rainbow worms crawling all over my cake soap!

Here is the cut to see how it looks like inside.  Why not make a white cake inside just like the inspiration photo?  Well,

 my design concept is you only get to see a piece of rainbow right after a stormy sky, never see a rainbow in a perfectly bright sunny day!

Baking Soda Soap

Did you know that baking soda (sodium bicarbonate) is amphoteric (react with both acid and bases)?  I didn't until recently.  I know by combining baking soda with some kind of acid will set off fizz, that's how we make bath bomb (or fizzy) to self disperse in bath tub filled with water.  A quick kitchen sink drain cleaning is to flush down some baking soda with vinegar.  But, I've never tried reacting baking soda with a base.  I just learned recently that reacting with a strong base baking soda would turn into washing soda which is a water softener.

Since baking soda reacts with lye which is a strong base, making cold process soap with baking soda is somewhat tricky.  I have seen soap makers failed by adding too much baking soda into the soap batter.  Too much baking soda added would end up off setting the normal saponification process and resulting in mushy soap, which is not soap at all.

As curious as I am, I just have to try this.  I live in a hard water county, majority of our water source is from the underground.  We did install a heavy duty water softener tank in our garage where the water enters the house, but it's never as good.  In fact I cannot bring myself to drink the tab water, it tastes funny, yucky.  I can never have a luxurious bubble bath with 10 inch high foam because my water is hard.  If adding baking soda in soap can help combat the hard water and cut down soap scum I think I would feel like I hit the jackpot.

To prevent baking soda off setting normal saponification I decided to use lower lye discount and only add 5% of the oil weight.  Since all I heard from other soap makers' horrified story is that baking soda reverses trace, I decide to take a water discount.  With 5% lye discount, 5% baking soda, 33% lye concentration, my first baking soda soap didn't go too well.  It went way pass plan A, totally skipped plan B straight to plan C which is just trying my best to squish all I can into the mold before it started to harden.

 I was not surprised at all when I unfolded this small 5 bar test log, there were potholes EVERYWHERE.

It was very bad.  This photo was taken after I tried to patch up some potholes using the scrap soap from the soap pots. There wasn't enough scrap to fill all that holes.  I had to sacrifice 1/2 bar of soap to fill the rest of the holes.  These are the 4 bars left:

How did I fill those potholes?!  Soap is still considered soft and pliable when first unmolded.  All I have to do it smash it like clay and push it into the holes with a knife (or scrapper). This only works the first couple hours of the soap out of the mold, else it gets too dry to work for seamless patching.

2 days later I took a sample piece to the sink for lather testing.  I can still feel the baking soda, it smells powdery and a little chalky, but not scratchy.  So far I'm not seeing a noticeable different in lather, maybe I'll wait a few weeks to wash again.

How Exact Can I Recreating a Soap Design?!

Have you ever gotten into a situation where you accidentally (or not) created a soap that's surprisingly great and would love to recreate it again and again but just can't?!

I made this soap inspired by a color palette from Design Seeds:

I really like this vibrant happy summer color combination in a white soap base.  Unfortunately the yellow color faded to almost nothing within 2 days.  Here's my previous post about color fading: Disappointing Color Fading  

It looked like this 2 days later:

Now, I really, really want to recreate this!  Give my yellow back!  Without the yellow, the soap just doesn't look the same!  Without knowing exactly why the yellow faded so fast, either the colorant or the fragrance, I decided to use a different scent AND a different yellow, I am NOT doing this the 3rd time!

Four weeks later, all colors settled a little, not as neon but didn't fade!  Thank goodness there's not 3rd time!  The faded 1st batch still smells great and good soap but too bad the look is not up to part, it'll go to the unsellable pile for personal use or donation.