I know you are probably tired of hearing these questions, but I have yet gained any faith in the soap testing. today, I tried once again to test the latest batch after what I think is finished washing.

I put 100ml of IPA (100%) then added the blue indicator. It turned to a light to medium blue. I added my 10ml of BD and instead of blue it gets yellow-green. Two small drops and it's bright yellow. I though, "great, little soap". But when I did the test on a sample was not dried and actually had soapy water at the bottom, the test came out with the same result.

STill a 3rd test with unwashed BD that had separated from the gylc from last batch. Same exact result.

Last test was again with the washed and dried BD, only this time I used red indicator to blank the 100ml of IPA. It took about 1ml to get and keep a slight purple tent. Added the Blue and it did turn blue, then took 1ml of HCL to get it to turn yellow. So it takes about the same amount of HCL than it did the KOH solution.

Why doesn't my tests look like the video?

IROKCJ5

UPDATE: Since I thought the soap test was indicating low soap ppm, I took the sample and froze it, then let it unthaw. When it unthawed, there was dark stuff that fell to the bottom. I added warm water and did a shake test. Soapy water and a slimy bubbles in the middle layer. I guess my interpretation of the soap test was wrong.

I'd love to know what I'm doing wrong. I've bought 100% IPA from utahbiodiesel, new blue indicator, fancy pipettes. I've followed the instructions to the "T" in preparing my solutions.

Does anyone else have issues with performing soap tests? Did you fix the problem? How?

thanks.

So here is what you should be doing:
Take 100ml IPA, and 5g of your unwashed biodiesel or 100g washed bio. Now if you want to get serious, add 2mL phenophtalien and see if there is a color change to pink. If there is that means there is leftover catalyst in your bio. Titrate the solution until it becomes clear w 0.1 or .01N HCl. Use the amount of titrant to clear used to find catalyst amount. Then add your amount of bromophenol depending on what percentage it is. And titrate it until yellow. This is the amount of soap. use the formula: (ml's titrant used)*(normality of titrant)*(320? (check me on this, the mass of potassium oleate)/sample weight*1000. Then multiply this number by a million to get ppm.
However if you add bromophenol to your IPA/bio mix and it turns yellow it means you have acidic bio (not likely) or your IPA has gone bad (it gets acidic with age) you shouldn't be freezing your bio and then doing a soap test cuz the soap will fall out of solution. Also just pick up 92 or 99% pure IPA from the pharmacy it doesn't matter if there is a little bit of water.