Lovehound said:
Please explain then why we add some of the superfat at trace, and also why we add colorants and scents at trace? I can appreciate that some of the volatiles in scents benefit from the reduced time of exposure to heat, but why not add all of that stuff just after the lye hits the oil?
Based on the info I receieved from the chemist over at the other soaping forum that I mentioned, I personally don't add any of my 'superfat' at trace. All my oils/fats go into my soap pot before the lye even hits them.
What I do is plug my soap recipe in over at the SoapCalc, being sure to specify the superfat percent I would like my soap to have by typing it in the 'Superfat/Discount' box near the upper right corner of the page, and then the SoapCalc figures for me how much lye I'll need in my recipe to saponify my soap at the level of superfat that I specified.
I figure that since only 5% to 10% of the oils/fats have actually reacted with the lye at trace, it's virtually impossible to have any control over which oil/fat will remain unsaponified, and so it just makes better sense to me to me to add everything up front and adjust the lye amount so it will leave a certain percent of unsaponified oils/fats, whatever those oils/fats may end up being.
The only reason I know of that people would add oils/fats at trace is because of the outdated info in most soaping books that unfortunately gets passed down unquestioned and/or unchallenged. Like Marr said, our soaping tools have grown more sophisticated and this is a great time to be a soapmaker.
As for colorants being added at trace instead of right after the lye hits the oils/fats: I have no idea why people would do that, for it's perfectly fine to add the colorants right after the lye hits the oils/fats- and even before if you are doing a one-colored soap. When I do a one-colored soap, for instance, I mix my colorant right in with my oils before the lye- except for ultramarine violet, that is. I learned through trial and error that my um violet will stay true and not go gray on me if it's added after the lye instead of before. To me, as a general rule, the earlier you add the colors and the thinner that your soap batter is, all the better.
Regarding fragrance being added at trace- this is one of those 'hot potato' subjects. I know of soapers who add their fragrance to the oils/fats before the lye and swear that it is perfectly fine and works great for them, while others say the opposite. I suppose it's just one of those things that depends on a lot of variables, not the least of which is using a 'prone-to-siezing' fragrance oil. With fragrance, I guess it's just one of those things that can only be found out by personal trial and error when best to add it.
HTH!
IrishLass