Potassium hydroxide for Lye Bath.

[Charles Marchand]

Hi everyone.

I make biodiesel and use Potassium Hydroxide (KOH) as the catalyst so always have over 50 lbs on hand.  In making Biodiesel, you use more of it then Sodium Hydroxide (NaOH).  So I just added about 22 Gals of water to a drum and added 5 lbs. of KOH.  I added my 12” Lodge DO that is in need of re-seasoning and a Lodge Camp Oven I picked up at a yard sale.

I did not find anyone using KOH so this may be of interest to a few people.

I will report my progress.

[Charles Marchand]

I opened the top this morning to drop in our square skillet.
The water is turning black so I guess it is doing something.

[Chris Stairs]

Hi C.J.,
 Welcome to WAGS!

  I always look for 100% sodium hydroxide for cleaning iron. Some drain cleaning products contain certain other chemicals, and I have always been told to avoid those, as they may not be food safe, like the lye most certainly is.

  Your posts have made me curious about this, so I have looked up some info on corrosion of common metals by chemicals. Potassium hydroxide is chemically very similar to sodium hydroxide, the biggest difference being that it is more expensive. If I had a big ol bag of the stuff sitting around, I would probably want to try it out, as you are.

   It does not react much at all with carbon steel, but it will corrode cast iron to some extent(more so than the sodium hydroxide). For this reason, I would limit experimentation to items that I did not have an emotional attachment to, and I would not leave the iron in the container any longer than necessary.

   One of the best things about using sodium based lye is that the items can be left for an extended period, months or even years. If you have or could find some totally worthless item, cracked, warped, Chinese, whatever, and see what a prolonged bath will do.

  I will be following this thread with great interest.

Chris

[Tom Neitzel]

I actually have used KOH for the past year or so for my cast iron cleaning.  I found that the flakes that I get actually dissolve a little easier.

As far as cleaning, it is at least equal to the sodium hydroxide that most folks use.  Even cleaned car engine parts nicely too.

Just a bit of history.  Potassium Hydroxide is the actual Lye that is made from wood ashes.  This is the stuff that was used to make soap, and pearl ash (an early leavening agent) in the old days.

After learning that I ran across it and decided to try it.  It is ever so slightly more expensive and harder to find, but works just great.

That's great that you can use something you have on hand.

Tom

[Tom Penkava]

I actually have used KOH for the past year or so for my cast iron cleaning.  I found that the flakes that I get actually dissolve a little easier.

As far as cleaning, it is at least equal to the sodium hydroxide that most folks use.  Even cleaned car engine parts nicely too.

Just a bit of history.  Potassium Hydroxide is the actually Lye that is made from wood ashes.  This is the stuff that was used to make soap, and pearl ash (an early leavening agent) in the old days.

After learning that I ran across it and decided to try it.  It is ever so slightly more expensive and harder to find, but works just great.

That's great that you can use something you have on hand.

Tom

Not cast iron, but another use, my brother and I have made our own lye from wood ash for years to settle the waste in the out door out house where we go camping.  Fairly simple process to do.

[Charles Marchand]

Thanks everyone for the welcome and comments.

Tom N, It’s good to hear someone else has used it successfully.  How long have you left Iron in the KOH bath?  One of the items in the bath now is my DO my mother-in-law gave me years ago.  I would hate to damage it.

I checked my last invoice from Univar and I pay 1.70 per pound for KOH.  I usually buy two 50 lb. bags at a time.   KOH keeps the glycerol byproduct of biodiesel liquid at about 45 deg and above.  This makes it more forgiving then NaOH that can clog your reactor if you do not get it out before it cools down.  The additional cost of KOH over NaOH in making Bio is about a couple cents a gallon.

I picked up a bottle of Flaxseed oil today at Wally World.  I will be trying it for the first time.

I will try to get some pics up soon. 

[Cheryl Watson]

CJ.... I would recommend skipping the flaxseed oil, and choose another.  It will save you headaches down the road.  Flaxseed looks good at first, but once put to use, will flake and peel into your food.  Many of us look upon Flaxseed oil as a great myth!  :D

PAM, Crisco, Grapeseed, and other oils are recommended, and perform great over time.  :)

[Bob Henrick]

I actually have used KOH for the past year or so for my cast iron cleaning.  I found that the flakes that I get actually dissolve a little easier.

As far as cleaning, it is at least equal to the sodium hydroxide that most folks use.  Even cleaned car engine parts nicely too.

Just a bit of history.  Potassium Hydroxide is the actual Lye that is made from wood ashes.  This is the stuff that was used to make soap, and pearl ash (an early leavening agent) in the old days.

After learning that I ran across it and decided to try it.  It is ever so slightly more expensive and harder to find, but works just great.

That's great that you can use something you have on hand.

Tom

Tom, I wonder if one could use lump charcoal ash to make KOH. charcoal ash is essentially wood ash since lump charcoal doesn't need a binder to make it hold together like briquets do, it seems to me that it should work.

[Chris Stairs]

C.J.,
This is the page of info I used to look up the corrosive properties of the two chemicals. It seems that both kinds can corrode iron if used in too high of a concentration.

 I do not know that any of this is relevant in practice. Perhaps at the ratios commonly used, there would be no damage to the iron, even in an extended soak. I tend to be most cautious with family pieces.

http://www.roymech.co.uk/Useful_Tables/Corrosion/Corr_metals_1.html

[Greg Stahl]

if one looks at the periodic table.... KOH vs NaOH, there is not much difference.  IMO, it is not based on experience,but only science.   KOH should be ok too.

Let me know if there is a problem, as I'd like to know from a science point of view.  thanks, greg

[Tom Neitzel]

Bob, it looks like you can use lump charcoal to make the lye.  Just google something like "how do I make lye from wood ashes."  I don't really think it would be worth the work, but fun just to see how it is done.

Tom

[Claudia Killebrew]

Or you can make lye with salt.

http://www.youtube.com/watch?v=nue1ZGSleEo

[Charles Marchand]

The KOH seems to have worked.  I re-seasoned this Skillet this afternoon.

3 coats of Pam.

I will pull the DO out tomorrow.