I have answered some of these questions in the comments....but I know not everyone reads comments, so time for another post about my new favourite topic!
I did forget to tell you fine folk that one site mentioned this soap is not recommended for silk or wool, I'm not sure why. I may make a point of throwing some old wool socks in to my next load just to see what happens.
I washed my undies and delicates in it, they came out fine. I did a load of very dark clothes and they also seemed great, no fading or residue that I noticed. (and wow did I look!) That's not to say it might now cause some fading down the line, but normal detergent does that, too. I'm willing just to wing it for now.
As far as washing really dirty clothes go, I didn't actually have any of those, so I can't tell you how this is going to work on hardcore grime. On the other hand, most people tend to separate the really nasty stuff from the lightly soiled stuff, anyway, so worst case scenario you could use the homemade stuff for regular loads, and commercial stuff for the heavy duty ones.
If any of you try this, PLEASE let me know how it worked for you. I gave samples of this to nine people today, and I know four of them specifically decided to do a load of laundry tonight so they could try it. As soon as I have more first hand info for you, I will be sure to share.
As Robbyn so rightly pointed out, many recipes you see on line call for something called fels naptha soap (whatever THAT is)...but they also usually say, "if you can't find it, use Ivory." The Borax comes in a green box with an old fashioned picture of a little girl on it. The washing soda was right next to it, in a big blue box under the product name "So Clean". It is made by Arm & Hammer, but again, not the same thing as baking soda.
Oh, and one last thing....one of the many websites I found the recipe was the David Suzuki Foundation. And if it's good enough for the good doctor, then it's good enough for me, lol !
EDITED March 19 to add: I have now read that bleach should never be used in conjunction with this soap. Why? I have no diea, I assume it is some chemical reaction. So make the soap. Skip the bleach.