Biodiesel and SVO Forums Home
new to BD - KOH soap questions

This topic can be found at:

March 03, 2014, 04:37 AM
Riz C
new to BD - KOH soap questions
Greetings all from Jakarta, Indonesia.

Have a feeling I might be the only Indonesian in this forum. Just recently got into brewing BD from waste vegetable oil using KOH and methanol as catalyst, and quite sure that I'm one of very few (can count on your two hands) used cooking oil BD producer in the country (all others uses gigantic amounts of Crude Palm Oil for their feedstock in their humongous reactors).

Anyway, lots of things to ask in this forum, however firstly need some info on making soap (both bar and liquid) with KOH-based glyc. Read quite a lot of stuff the last few days and can feel smoke coming out of my ears but the general consensus that I get is that KOH-glyc is better for liquid soap, however some have succeeded in making bar soap by using NaOH as the saponification element. Does this sounds right and on the right track?

Now currently trying to make a small test batch of liquid soap (300 ml KOH-glyc demeth at 110C for 20 minutes, 80 ml water mixed with 14 g KOH, another 300 ml water to dilute). Glyc soap mixture smells neutral now instead of methanol-ish. Now to wait 2 weeks to cure and we'll see how that works. Any help/advice/critique will be much much appreciated.

March 11, 2014, 11:07 PM
Riz C
No reply?

Ok a quick update then. The test liquid soap has been added with jasmine scent (maybe a bit too much). Having trouble reading the pH with test strips because the colour of the glyc is distorting the reading but looks like 10-11. Should I wait for a bit longer before testing? Thx
March 11, 2014, 11:26 PM
Riz C; Smelling for methanol odor is bad. Enough methanol can cause permanent blindness or worse. In my opinion breathing methanol vapors ought to be intentionally avoided.. I made KOH soap from palm kernel flakes. My KOH soap is a solid. I've read that NaOH soap is more solid than KOH soap. I read that "soft soap" is KOH soap. There are others much more experienced in soap making on this biodiesel forum than me. I hope you know that soap is fatty acids and KOH, NaOH or LiOH. Some glycerine is in it, but the glycerine is not the actual soap. An acid + a base makes a salt plus water. So, free fatty acids + NaOH, KOH or LiOH (a base) makes a salt (the soap) + water. Soap is a salt.
March 18, 2014, 11:38 AM
Legal Eagle
You can test for methanol residue by demething it and taking a small sample out and place it in a shallow dish; now strike an open flame over it while it is hot. If it ignites you have residual methanol.

The evaporation method is to bring the gly to a slow roll and let it simmer for 40 min for EACH liter of glycerine, then perform the open flame test.

When soap making one of the priority considerations (unless you use a bunch of synthetics and chemicals) is the type of original feedstock oil as they all have their own properties and as such behave differently. For liquid soap in a glyc that has been processed using KOH is 800-900ml water and 40gr KOH PER liter glycerine. Glycerine is very hygroscopic (absorbs water easily) and once the caustic mix is well blended it will not separate. If you process hot (below boiling) the soap will be ready to use as soon as it is cooled down. Bars are another issue altogether and are even more dependent upon what the feedstock oil is as to how to process.


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

March 18, 2014, 11:04 PM
Legal Eagle: According to a formula I saw, for soapmaking water only needs to be present for the saponification reaction. Little or no water is needed for the free fatty acid neutralisation reaction. Aren't you advising an excessive amount of water be used? 800 ml per litre of glycerine plus 40 grams KOH? Just thinking about it.
March 19, 2014, 09:52 AM
I use more water than that for my liquid soap. It is needed to reduce the viscosity to a consistant level. Some glycerin is thicker than others, depending on FFA chain length.
March 21, 2014, 06:35 PM
Originally posted by BobAbbey:
I use more water than that for my liquid soap. It is needed to reduce the viscosity to a consistant level. Some glycerin is thicker than others, depending on FFA chain length.

Nice website Bob,
We make an industrial version in batches.
The glycerin comes out of demeth @ about 200 F and goes right in to another processor with
38 grams KOH per litre ( We came up with that number based on another LE formula based on T # )
and just enough water to carry it in .
By the time the KOH/water is mixed in,
it's thick and it's soap, then Mix in the water.

We are at a 3-1 ratio Water to Glycerin and
being told not to change anything.

As you know it's a real simple process that yields
a great natural product that completes the circle .

BTW we started using demethed glycerin and true soap 1/2 &1/2 as bar oil for the chain saw.
It's working really well. We tried a version that was water and KOH soap about 1/2 and 1/2,
I like the glycerin/true soap version better.

1999 K3500 Dually with a new AMG 6.5TD turned up a bit by John Kennedy
Chevy DMax Totaled thanks to a 20 year old in a Mustang
Mercedes 300CDT
John Deere
On B99.?
September 04, 2015, 07:53 PM
I'm just learning how to move around this forum and am a bit lost. I'm just starting to make bio using KOH. I'm only on my 3rd batch but previously got soap down to 42ppm. Hoping I'm testing everything correctly.
I'd like to start making soap ASAP and reading so many different things I'm a bit confused. Seems like you just demeth (at various temperatures but around 250F or so). Then you add more catalyst? I am surprised since KOH is caustic. I didn't realize that it would be added and just want to make sure. There are so many different ideas, I'm hoping someone can simply direct me to a source that has been tried and tested so I can start there. Or, if someone wants to spell it out here but I'm sure the resources are out there and I just need to be pointed in the right direction for a good recipe for biodiesel made with KOH.

1997 Dodge Ram 2500
September 05, 2015, 05:11 AM
Hi Azjed, Click on the 'FIND' option at the top of the page, type in 'SOAP Legal Eagle' and you should find what you are looking for. Jim.
September 05, 2015, 11:17 AM
Will do. Thanks for the direction

1997 Dodge Ram 2500