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Soap makers face a problem called Dreaded Orange Spots, often referred to as DOS.
These spots have been widely discussed for decades. As the soap ages, sometimes it develops
areas of rusty colored spots. Most people consider them to be a sign of rancidity of the oils.
The spots start off as small round dots and will spread throughout the entire bar over time.
Dr. Kevin Dunn, known as the caveman chemist, is a professor
and a soap maker. He has conducted scientific testing with his
students on a number of soap making issues including the study of DOS.
I attended a presentation by Dr. Dunn at the Handmade Soap Maker's Guild where
he spoke about his study results. It was fascinating. I wanted to do my own
experiment using Dr. Dunn's recommendations.
On the same day, using the same identical supplies,
I made two batches of my Vestal Castile Soap. The soap
is 100% certified organic olive oil, distilled water and
lye. Nothing else. No fragrance, no color. I did cold
process, soaped between 4 & 5% superfat. To the second
batch, I added .1% each of EDTA and Sodium Citrate and
.05% BHT. These are the additives that Dr. Dunn discussed
in his presentation on the prevention of DOS. The EDTA and Sodium
Citrate was dissolved in water, the BHT dissolved in warmed oils.
Both batches were brought to full gel.
At all times, the test bars were kept together
in identical curing and storage situations. They
were cured in my soap studio for 8 weeks. One bar
of each was put in muslin bags (I have always sold
my bars in muslin), and one bar of each was left
unwrapped. They were kept, untouched on a shelf
in my office at the store. This would be the same
retail environment as my soap cart. We only maintain
the heat and AC during store hours, so the soap was
exposed to some very hot humid conditions during the
summer months, and 55 to 60 degree cold during the winter months.
Here are the pictures of the results. As you will note,
the two bars with the additives are sparkling white, pristine
with no signs of DOS. The wrapped bar with no additives shows
one small, very light DOS developing in the upper right hand
corner of the bar, the unwrapped bar with no additives is almost
completed covered in DOS on all sides. It is also interesting to
note the unwrapped, no additive bar shows great difference in
shrinkage and cracking.
I have always believed that selling in muslin gives the
best protection. I have had bars deteriorate on the
display shelf while the same batch bars in the muslin
bags stay perfect. When I compare the bars that had no
additives, the one that was unwrapped is drastically
impacted by exposure to light and air. My belief that
muslin is best for my soap has been validated. The results
of this experiment also show that simple muslin packaging
provided similar protection against DOS as did the chemical additives.
The top bar is the additives in muslin, next
is no additives unwrapped, next is additives
unwrapped, and last is muslin no additives, note
the faint yellow spot in the upper right hand corner of the last bar.
This is the back side of the same bars.
The pictures are not enhanced, they are taken in natural light.
I hope this provides some useful information to my fellow soap makers.
Happy soaping!
Bonnie
Author:
Bonnie Bartley, Soapsmith with over 30 years of experience. Check
out her website and
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