BB's KOH purity in late 2014?

[lenarenee]

Hi everyone, I finally have chance to make liquid soap using koh I purchase in late 2014 from BB.

Double check the level of purity, I see BB's website says that as of mid 2015 it's koh is 90%. Any idea what the purity level was before that? I have water and flakes measured already so I'm trying to get an answer asap.

edit: when back in my records to find the koh was ordered 10-14. Then read through the review on BB's site to see comments and found that koh used to be 97% pure in early 2015. So I'm recalculating my recipe with the 97%. It it's wrong, then I'll just have a higher sf than 3%.

 

[topofmurrayhill]

Hi everyone, I finally have chance to make liquid soap using koh I purchase in late 2014 from BB.

Double check the level of purity, I see BB's website says that as of mid 2015 it's koh is 90%. Any idea what the purity level was before that? I have water and flakes measured already so I'm trying to get an answer asap.

edit: when back in my records to find the koh was ordered 10-14. Then read through the review on BB's site to see comments and found that koh used to be 97% pure in early 2015. So I'm recalculating my recipe with the 97%. It it's wrong, then I'll just have a higher sf than 3%.

I'm sure it wasn't 97% pure unless they were selling it by the gram rather than by the pound. KOH absorbs water from the atmosphere very readily. Moreover, the manufacturing process also leaves residual water in the product that is very difficult to remove from KOH. Not worth the expense either, since the water isn't a problem for most purposes. For quantitative applications they simply determine the percentage of KOH in the material and proceed on that basis.

Therefore, the purity of the KOH you buy is much lower than that of NaOH. The typical grades you see are marketed as 85% or greater KOH and 90% or greater KOH versus 99% for sodium hydroxide. Regardless what you buy, neither you nor the supplier know the actual purity unless it has been analyzed, or you titrate it yourself. The standard procedure in soaping is to assume 90% purity, hence Soapcalc's 90% checkbox for KOH.

Or at least that used to be what people knew about soaping with KOH. Between suppliers that are confused about what they're selling and people claiming you can guess the purity of your KOH and use that number, things seem to have gotten a bit muddled. Bramble Berry is probably not selling KOH of lesser purity than before, but they are now describing it more accurately.

Or at least that is my take on the situation.

 

[lenarenee]

Thanks topofmurrayhill. Sounds like we have to get used to KOH being more guesswork than NaOH.

I went with AnneMarie's statement at 97%, even knowing it might be "wrong". Was going to use Summerbee's calc since it calculates at middle of the road, but was too impatient figuring it out how to use it.

Went to soapcalc, used 100% purity level, formulated at 1% SF, and figured I'd have at least a 3% sf, but probably more. Good enough for me - just want a nice soap that's easier for kids to use.