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Hi all - made my first batch of BDG soap last week and have a couple questions. My glycerin has been demethed and stored in 55 gallon drums for a year or so (very fun to dig out). Glycerine PH was 8.55 at start. I used 2 gallons of glycerine, 2 quarts of water, and 10 ounces lye. brought glycerine up to temp, added solution and stirred for ten minutes or so then poured into mold. Solidified good overnight and cut into bars. After a week th PH of soap is 12.2 and seems very soft and rubbery. Is there something I need to do different as I would like a harder bar soap?


Bio production since 12/10/07
House on B100
01 Excursion on B100 warm weather - B50 cold weather.
 
Location: Northwest Iowa | Registered: March 02, 2008Reply With QuoteReport This Post
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I read on the internet that the pH of potassium soap is about 10.5. If that's true then it seems to me that your pH is too high. I wouldn't put it on my skin but might wash cotton clothes in it. I don't know how to make a harder bar of soap.
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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How do you measure the pH of your soap?
 
Location: Texas | Registered: April 27, 2011Reply With QuoteReport This Post
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I have a very expensive PH test probe that I had to purchase a while back to test the PH of beef sticks to make sure they were shelf stable. It works great for biodiesel production also.


Bio production since 12/10/07
House on B100
01 Excursion on B100 warm weather - B50 cold weather.
 
Location: Northwest Iowa | Registered: March 02, 2008Reply With QuoteReport This Post
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The PH of all soap should range between 9 and 10.5, or slightly alkaline.

12.5 is a little caustic hot and could be uncomfortable on the skin, however this is approximately the PH of what is known as "lye soap" a known remedy for poison ivy/oak/sumac in traditional soap. I say traditional not to be confused with modernist, which is the way people who bury you in chemical content do. Tradition has a long history of natural soap making.

The soap made from the biodiesel glycerine does the same job without the harshness of conventional "lye soap", but with a lower PH, around 10.

The PH of your soap will drop as it cures if you did not process it using the hot process method, time being your friend. Wait a could weeks and test again.

Unless you are one of those who can't figure our how to do it naturally there are a host of chemicals and synthetics additives than can be used to stiffen up soap, however, IMO that defeats the purpose of what we are trying to accomplish.

The ability to get a stiffer bar will depend on a few things, the original feedstock being the most important, as there are short chain oils and long chain oils and each has its own set of characteristics. Like I explained in The Guide, what is great for biodiesel isn't so good for bar soap as far as feedstock oils go. You may want to consider the use of a binding agent such as lard or palm kernel oil and use that in ever increasing percentage until you get the result you want.

I make perfectly fine bar soap forma canola base feedstock. This is probably the most challenging of all feedstock oils for bar soap. I bind it up using rendered organic pig fat, and with a few other tricks get a great bar that lathers extremely well and lasts a long time.

HTH



** Biodiesel Glycerine Soap - The Guide
- on 5 continents helping people make & sell soap from the Biodiesel Glycerine.


 
Location: :-) Great White North eh ? | Registered: December 10, 2004Reply With QuoteReport This Post
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Thanks for the responces. This is my first batch so will need to learn a few things. I have pretty much unlimited access to tallow and lard(own a butcher shop) so I will experiment with using them. I want to keep it as chemical free as possible.


Bio production since 12/10/07
House on B100
01 Excursion on B100 warm weather - B50 cold weather.
 
Location: Northwest Iowa | Registered: March 02, 2008Reply With QuoteReport This Post



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Tallow will be disappointing in the lathering department, but lard is altogether the opposite. You can email me if you want at soapinfo@blackcrownsoap.com



** Biodiesel Glycerine Soap - The Guide
- on 5 continents helping people make & sell soap from the Biodiesel Glycerine.


 
Location: :-) Great White North eh ? | Registered: December 10, 2004Reply With QuoteReport This Post
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Cobbler,
I would dispose or re-work the batch of soap that has a pH of 12.2. After a week or two if the pH remains that high it will NOT go down. The pH of your BDG soap should be between 9 and 10.5. I would shoot for somewhere just below 10.

You can superfat your BDG soap to lower the pH as well. I will be doing a BLOG post soon to talk about the best way to superfat BDG soaps.

Cutting out BDG with the methanol removed, not easy. I feel ya!!

I suspect you used a SAP value that was too high. If you like you can send me a sample of your BDG and I will do a SAP test for you and you can compare it to your own SAP test. If you go to my blog you will see detailed instructions on perfoming the KNC SAP test.

A rubbery soap is the norm if you are using "soft" oils to make your Biodiesel. If you used coconut oil, palm kernel oil, lard, tallow etc. your bars would be harder "out of the box".

There are a number of traditional ingredients you can use to accomplish the task of hardening your bars.

On my website http://www.knicenclean.com/ you will find the largest free BDG soaping content on the internet. SAP Testing, Ingredient Properties, Soap Glossary and Recipes just to name a few.

I developed it to be a single point of BDG soaping information to help the biodiesel community use their BDG to make the best soaps possible.

Happy Soaping!


-Rick

http://www.knicenclean.com your single-most largest free BDG soaping content on the internet.
SAP Testing, Ingredient Properties, Soap Glossary and Recipes just to name a few.

Making Biodiesel Byproduct Soap Learn how to use your biodiesel byproducts to make great bar and liquid soap!!!

"Closing the loop on biodiesel production one bar at a time!"

Beware of the Dunning–Kruger effect.
 
Location: S.E. Michigan | Registered: April 15, 2007Reply With QuoteReport This Post
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Stearic acid works wonders! I use 300 grams of glycerin to 70 grams of stearic acid..You will need to adjust the amount of caustic you use.
 
Location: la gloria | Registered: October 02, 2010Reply With QuoteReport This Post
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quote:
Originally posted by sethb100:
Stearic acid works wonders! I use 300 grams of glycerin to 70 grams of stearic acid..You will need to adjust the amount of caustic you use.


Sethb100,

Here is a recipe I created from your post using the KNC Soap Calculator. Of course one will have to use the proper SAP value for their BDG. You are right about at 20% stearic, which seems to be the "sweet" zone for using fatty acids.

9.88g NaOH of the 20.38g NaOH is to saponify the stearic acid.

300g Biodiesel Glycerin (BDG) (25% SAP)
70g Stearic Acid

Caustic Solution:
20.38g NaOH
56g Distilled water

Optional:
6.66g Scent of your choice
11.10g Sodium Lactate


Here is another using stearic, lauric and myristic. This should be as hard with a boatload extra lather.

300g Biodiesel Glycerin (BDG) (25% SAP)
50g Stearic Acid
10g Myristic Acid
9g Lauric Acid

Caustic Solution:
21.10g NaOH
57g Distilled water

Optional:
6.66g Scent of your choice
11.07g Sodium Lactate


This recipe is similar but using coconut oil instead of the myristic and lauric.

300g Biodiesel Glycerin (BDG) (25% SAP)
50g Stearic Acid
20g Coconut Oil

Caustic Solution:
21.35g NaOH
58g Distilled water

Optional:
6.69g Scent of your choice
11.10g Sodium Lactate

I formulated these recipes in just a few minutes using the KNC Soap Calculator. Just remember to use the SAP value that is specific to your BDG when using the calculator.


-Rick

http://www.knicenclean.com your single-most largest free BDG soaping content on the internet.
SAP Testing, Ingredient Properties, Soap Glossary and Recipes just to name a few.

Making Biodiesel Byproduct Soap Learn how to use your biodiesel byproducts to make great bar and liquid soap!!!

"Closing the loop on biodiesel production one bar at a time!"

Beware of the Dunning–Kruger effect.
 
Location: S.E. Michigan | Registered: April 15, 2007Reply With QuoteReport This Post
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