Oh, that Distressing DOS!

Five Ways to Avoid it

The appearance of DOS distresses soapmakers around the world.

You make a lovely soap. It cures well and feels great on the skin. Suddenly, you notice orange spots. You peer closer, poke at the soap and notice that the spots are soft and translucent. You have DOS.

What is DOS? What causes it? How can we prevent it?

DOS is an acronym for Dreaded Orange Spots. It is caused by oxidation, the same process that causes rust on metal and browning in soaps with vanillin as part of the fragrance. It also happens as a result of resting soap on certain metals.

Of course, we cannot prevent oxygen and moisture from reaching our products; can we do something about DOS?

Fortunately, you can take steps to prevent DOS. Read further to find ways to prevent it in your bath and body products.

1. Keep the percentage low of oils high in linolenic and linoleic fatty acids. Some of the oils high in these fatty acids include grapeseed, low oleic sunflower, soybean and canola; apricot kernel, sweet almond, and many of the specialty oils that we love so much. Conventional wisdom says to keep these oils to no more than 15 percent of the oil total. One great source of information on fatty acids in oils is http://soapcalc.net/calc/OilList.asp. Simply choose a fatty acid and search where your chosen oils fit in the list. If the oils are high in linoleic or linolenic, keep the total percentage to 15 percent or under in the formula.
2. Watch the superfat. Superfatting over 6 percent may leave too much free-floating oil in the soap that is subject to DOS. It is not a guarantee that DOS will take place, but it is a factor to consider if you struggle with DOS.
3. Pay attention to metal. Not all metals are compatible with soap, so know the type of metal that the soap rests on. Stainless steel is a safe choice. I can tell you from experience that nickel is not. Yes, I learned the hard way! I even found that laying paper toweling or wax paper over the shelving did not prevent DOS.
4. Some believe that impurities in water can cause DOS. Many soapmakers use tap water without consequences. Others, however, find that switching from tap water to distilled results in DOS-free soap. Since the local water supply differs widely around the world, it is a factor to consider.
5. No sun for soap! Keep soap out of the sun or extreme heat. Both can cause DOS.

Incidentally, it is a widespread opinion that rancid oils cause DOS in soap. My own experiments in including rancid oils have not borne that out. With a reasonable superfat, between 4 – 6 percent, I have made soap with rancid oils that does not produce DOS.

Have you found other causes of DOS? Do you take other preventative measures to avoid it?

photo by Jennifer Marie Hofmann