Making the best soap I can with quench oil (canola)

[paragon]

I'm going to use a couple liters of canola oil to quench some kitchen knives after heat treatment. That means the oil will be contaminated with metal, and a small percent of the oil will have been heated to vaporization temperature or set aflame.

The heat will cause oxidation and polymerization. Metal contamination and oxidation will make the soap tend toward DOS or off odors. My plan is to use 2% per oil of EDTA and an antioxidant. I know ROE was the only antioxidant found to be effective, but my understanding is that all antioxidants were tested at very low quantities, so another may be effective at a higher PPO. I will surely need a scent to cover any odors that occur. I want to use it at a high ratio (~60%) with plenty of lard to make it harder, and no coconut oil because I want smaller less dense bubbles.

Is there anything else you would do to make the best soap you can with this starting ingredient?

 

[shunt2011]

Regardless of what you do, at that high of a percentage you will likely still get DOS. I personally don’t think it’s worth the risk of wasting ingredients. I would try a batch and see what happens. I use EDTA as a chelation not an antioxidant. Though it may have a very low antioxidant ability.

 

[paragon]

The EDTA is to chelate the metal contamination in the oil. (Metals catalyze oil oxidation, but not all metals have the same effect or are active at the same temperatures.) The antioxidant is to prevent further harm from oxidation that already occurred due to heat and catalysts.

I decided to search for a more locally available antioxidant, and found to my surprise that BHT is recommended by Kevin Dunn on equal footing with ROE! BHT+Sodium Citrate is recommended even more strongly than ROE+EDTA. Why does nobody on the forum ever mention this possibility? In any case, I still need EDTA because of known metal contamination, but my antioxidant will probably be BHT.

 

[cmzaha]

I use BHT but very seldom mention it since many here are against it. It is used in combination with .5% Tetrasodium EDTA .5% Sodium Gluconate. Since I have used this combination my only dos issues have been with a popular OO soap recipe here. I am actually considering upping the SG 0.1 % at a time in test batches up to 1% testing if it can go that high.

My reason for the BHT was DOS issues when using lard which already contains BHT so I add in O.01 additional BHT it stopped my DOS issues