I got these instructions from The Ponte Vedra Soap Shoppe. It's a US site so the measurements are in ounces and the temperature in Fahrenheit but most scales & thermometers have both.
It cost around $50-60 but I filled two silicone cake tins (of which I got 24 slabs), 1 tray of shapes and 12 silicone muffin cases. So easily a few years supply of soap plus gifts. I got these boxes from Essential Oils and Soaps, they have a great range of soap making supplies. My good friend Jo also sent me this link to different soap making methods at Green Organics.
I'm now selling the good soaps on Etsy with my jewellery!
I made a Soap Making Tutorial video here.
24oz olive oil
24oz coconut oil
38oz vegetable shortening/oil
12oz lye (I bought this online from Essential Oils of Australia but I also saw it at Franklins under "caustic soda")
32oz distilled water
3-4oz essential oil
Tools (preferably ones solely for soap making);
Scales that weigh ounces
2 large stainless steel pots/bowls
3 large plastic jugs (enough to hold each oil)
2 wooden kitchen spoons (not to be used again for cooking)
2 kitchen thermometers
Rubber gloves (used solely for soap making)
Safety goggles (I used a snorkel mask because my goggles kept fogging up)
Soap mold of choice (silicone is easier but if using wood make sure you line* the bottom)
Cardboard the size of the top of the mold
Towel, preferably an old one you don't mind getting dirty
Put on your gloves and goggles (an apron will help too).
Weigh the oils out into the jugs.
Weigh essential oils in a bowl.
Weigh lye into one of the stainless steel bowls.
Weight water and slowly add to lye gently stirring with wooden spoon until all mixed.
Place thermometer in the mixture, it will heat up to around 200˚F.
Wait until the temperature goes down to 100-125˚F.
In the other stainless steel bowl mix in all the oils except the essential oils (the coconut oil and shortening may need to be melted in the microwave).
Place a thermometer in the oil mixture and wait until it reaches 100-125˚F.
Personally I found it easier to heat some of the oil in the microwave or on the stove before adding the water to the lye and then they seem to reach the same temperature quickly. If you're using half this recipe the lye will cool much quicker.
Once both mixtures are the same temperature slowly pure the lye into the oil mixture constantly stirring gently. Be careful of splashback as lye is an acid. I've since found that using a hand mixer on low works more effectively (and is less time consuming) that stirring by hand. I just picked one up from a thrift store.
Once you see "trace" (tracks in the soap) you can add the essential oils and colour if using. My colour didn't mix in well and just went speckly. They suggest if you're adding colour to take out a cup of the soap mixture, mix in your colour well and then return to the rest of the soap and mix in.
When you start to see patterns in the soap (around 10-20mins) you can transfer to molds.
Once poured into molds cover with freezer paper and cardboard and cover with a towel and leave undisturbed for 18hours.
After 18 hours you can remove the towel and cardboard and leave for another few hours.
Then you should have a hard enough soap that you can remove from mold.
If you are cutting your soap into pieces this is that stage for it.
These are my patchouli/sandalwood ones;
Keep soap in open box or drying rack - not touching each other - for 2 weeks minimum.
The longer you leave your soap the harder and milder it will be.
My soap was a bit yellow but I think that's because of the dark olive oil I used.
*Lining the mold;
To line a wooden mold cut a piece of cardboard that is the same size as the bottom and cover it with freezer paper/plastic. Then place a large piece of freezer paper on the bottom of the mold and place the covered cardboard on top, this way you can just lift out the soap.
After two weeks...
You can see the soap has turned a much nicer cream colour!
Please see my other post for adding colour (and it actually working, I hope)