I make 25 gallons of biodiesel every weekend for 6 months out of the year. I have a 100 pound drum of KOH that is now 2 years old and almost done. It's a sealed drum, which I open briefly when I am mixing a batch and I always seal it up tight when I am done.

Lately it seems that my 3/27 tests are showing signs of decreased levels of conversion. (I have more and more small bubbles of un-processed oil at the bottom). It appears that as the level of KOH in my drum goes down and the amount of air in the drum increases, the more problems I am having. I have a theory that my KOH is absorbing moisture and creating problems.

Does anyone have tips on keeping KOH dry? I am thinking of putting my next order of KOH in pre-weighed zip lock bags and using them as needed. Is that a good idea? I hate to throw away KOH. It's expensive!

Pre-weighed baggies are an excellent idea!
Just make sure to get the freezer burn ones so that they'll really lock out the air.

The other method you can use is a twist on lid like this:


I learned about these at a local food storage place a long time ago & liked them so much I started selling them on my site. I'm sure you can find them locally too.

I have a 5 gallon bucket that I attached one to and that's where my KOH goes. Each time I use the KOH, I reseal the bucket good & tight.

I had some KOH that'd been in the bucket for well over 2 years a while back & found it still worked great when a friend of mine borrowed some to make a batch with.

You can also get those small little containers & put them in it as well.
It's one of the way we sell chemicals.


I have a 2 lb'er here that I've had for quite a while and it continues to seal extremely well when I occasionally dip into it for demo batches.


Pre-sealed baggies in a 5 gallon bucket with one of these self-sealing twist off lids or using some small jars would probably do the trick nicely! I've also been known to store KOH in mason jars with self-sealing lids as well.

Just be sure you clearly mark your containers though so no one thinks they're instant mashed potatoes or something like that.

Hope that helps...

-Graydon

I bought a case of KOH a few years ago, it came packaged in standard 1 quart tin paint cans with the mash-on lids, each can holds over 2 pounds. I am still reusing these.

I use 5 gallon paint cans. They have a sealed lid. Given the rainy weather here in the Seattle area, I've left them out all winter and the KOH inside was bone dry every time I opened them.

Ah, yes, keeping your powder dry. When I open the bag it is with the express purpose of finishing the job, and that job is to pre-weigh the lot into zip-lock bags and then I seal these in an air tight bucket. When I need to use it I pop open the lid (and no air contact) pull out a baggie and that's it.

When doing the original filling of the baggies I make sure I am in a room that has had the air conditioner on for a couple hours (air conditioners dry out the air). That way I am not rapping a bunch of humidity in each bag.

HTH

I do it much like Legal except that my five gallon paint cans holding the pre-weighed zip lock baggies go into a refridgerator (compressor died) wth dessicant. The refer still has a good seal and the dessicant keeps the moisture down to close to nil.

Even with all these precautions I ran into a problem when I got a bag of KOH from my supplier that had a 2007 date on it. The gray looking flakes should have been a clue...