Used Vinegar Today - Have Questions...

[HowieRoll]

Hi All,

I finally used white distilled vinegar (5%) today, in an attempt to derive 2% sodium acetate. The calculations I used were so generously provided by TopOfMurrayHill from this thread, although I read many other threads on the subject, too. So thank you, everyone, for all this knowledge! I just hope I got this right.

First, the numbers:

Oils: 567g
Water (33.33%): 157g
NaOH: 78g
2% sodium acetate desired

After doing the calculations, I came up with these revised numbers to use:

Vinegar: 99g
Water (actually aloe): 63g
NaOH: 81g

I wanted to use fresh aloe in place of additional water, so I slowly mixed the 81g NaOH into 99g vinegar. I did this outside with the container planted into a snow bank to avoid any overheating issues. It melted a fair bit of snow but otherwise did not appear to do anything dangerous. I left it outside after mixing for about 5 minutes, then brought it into the cold garage to continue to cool down. Since the vinegar is 5%, I took this to mean the other 95% is water and figured it should be enough to fully dissolve the NaOH. Or maybe not?

However, the lye never got 100% clear. There were bits floating in it that just never dissolved, but I can't say for certain it was lye beads. I'm familiar with the "crust" that can develop on top of lye solution as it reacts with air, and these bits were most certainly floating in the solution, not on top. I added 10g of distilled water to the lye thinking that might help, but it didn't, really. To be safe, I ended up filtering the solution just in case. Interestingly, I tried to filter it through a coffee filter but the liquid never penetrated the paper. It just sat on top, defiantly. So I used a fine mesh strainer, instead, which worked.

Is this normal when using vinegar?

I appreciate any insight!
-Angela

 

[Soapprentice]

Following... I want to try this on my next one.

 

[earlene]

It happens to me with or without vinegar sometimes. When it does I do the same as you and filter through a stainless steel mesh filter.

With 99g of vinegar at 5%, you had 94g of water to 81g of NaOH for mixing. Since it only takes 81g of water to dissolve 81g of NaOH, you still had 13g to allow for the acetic acid to interact with the lye. And since it takes 28g of acetic acid to neutralize 1g of NaOH, you had enough of it to neutralize 0.46g of lye. Still within the formula as I read it. So your solution amounts are fine for mixing the NaOH. It's just something that happens sometimes.

I don't do my lye mixing outdoors. I do it in my kitchen sink, sitting the container right there over the drain just in case it starts to leak (I had that happen once with poor quality plastic) or boil over. My container is so tall, it has never boiled over, but the vinegar certainly does bubble up. Kombucha tea is another one that bubbles up when mixed with lye. So I use a tall pitcher for mixing lye and never fill it more than about half full or less when working with these types of liquids.

 

[HowieRoll]

Thanks, earlene, for sharing your experience. Before I started I made the same calculations you did and determined that the 99g of vinegar should be enough of a water content for the 81g NaOH. But after mixing it for quite some time those bits just never went away. But they also didn't necessarily appear to be lye beads, per se, but more like lye beads that had been puffed up by absorbing water, or like little lye beads with a halo around them. I should have taken a photo.

The vinegar never did bubble up, but I had left it in the snow bank for about 5 minutes to chill while I weighed the NaOH, and when I added the NaOH I did so slowly, much more slowly than normal. I would have mixed it all in the sink in the cold garage but figured since it was a high of 20F today and we have snow on the ground, might as well use Nature's walk-in freezer.

 

[DeeAnna]

I want to mention that most of the time when soapers talk about the solubility of NaOH in water, the unspoken assumption is the lye solution is at room temperature or warmer.

At temps below 50 F (16 C), the solubility of NaOH is reduced far below the usual 50% max NaOH that we normally assume we can make. By making your NaOH solution while the container was stuck in a snowbank, it's possible the mixture may have become too cool for the NaOH to fully dissolve, leaving some lye particles undissolved. Once the solution warmed to more normal room temps, any undissolved lye should have dissolved, however.

I haven't spent much time trying to figure out whether this really applies to your situation, but it's a possibility to consider.

I understand why people want to cool their lye solution down quickly, but this might have been a bit overkill.

 

[HowieRoll]

I unmolded the soap a little bit ago. There was some precipitation (small droplets) on top of the slab, but that happens on my soaps from time to time and is usually a problem that resolves itself (or I just dab them off). The drops didn't zap, just stung a little bit after a few seconds. The soap itself did not zap or sting at all.

However, it crumbled as I cut it, which I've never experienced with this recipe of oils (but it is also the first time I've used fresh aloe. Not sure if that might be part of the problem?). Overall, the soap seems to be firmer out of the mold than normal, and the parts that did not crumble cut more smoothly than normal. I think next time I will shoot for 1% sodium acetate and see what happens. This is all, of course, assuming my calculations/understanding were correct the first time around, a point about which I'm not entirely confident!

 

[HowieRoll]

DeeAnna, I was typing up my last post while you responded, and didn't see it until after I posted. But thank you for that additional bit of information! Of course, that makes a lot of sense to me now. duh I had seen a recommendation to chill the vinegar prior to adding the NaOH to help combat the extra heat it generates, so yes, you could say I took that to the extreme. :shock: Next time I think the cold garage should suffice, which is where I normally mix the water/NaOH solution before bringing it inside to finish cooling.

Thank you!