Did Aluminum Contamination Ruin My LS

[Willyd]

I just finished a small test batch of liquid soap and wound up with a considerable amount of unsaponified fatty acids clouding my soap. I am quite certain I calculated the amount of KOH and water correctly, so I doubt that is the problem.

I did however experience an unexpected problem during the cook. Turns out the shiny metal splash guard on my stick blender is made of aluminum not stainless steel! This went unnoticed for about 5 min. of blending time. By time I did notice the problem, the KOH had badly corroded the splash guard.

The question is could this have weakened or diminished the strength of the KOH causing some of the fatty acids to cloud the soap?

I guess I can't say the soap was totally ruined, I just have to sequester the batch until it settles then siphon off the good stuff.

 

[DeeAnna]

You answered your own question -- "...the KOH had badly corroded the splash guard..."

Yes, the reaction of the KOH with the metal of the SB bell did consume some of the KOH.

 

[Arimara]

Would you mind posting the brand and model of your stick blender? I'd like to know so I won't make the mistake of recommending it or buying it should I see it.

 

[Susie]

Would you mind posting the brand and model of your stick blender? I'd like to know so I won't make the mistake of recommending it or buying it should I see it.

^^Pretty please? It is easy enough to check with a magnet one you are handling in a store. But checking over the internet is a problem, and you could keep lots of folks from having problems.

 

[IrishLass]

^^Pretty please? It is easy enough to check with a magnet one you are handling in a store. But checking over the internet is a problem, and you could keep lots of folks from having problems.

Just keep in mind, though, that just because a magnet doesn't stick, it doesn't necessarily mean that a metal item is not SS and not worthy of purchasing to use in your soap-making. Depending on the iron content of the SS and a few other factors that come into play, you may or may not be able to get a magnet to stick to certain items of SS at all. This Scientific American article explains why: http://www.scientificamerican.com/article/why-dont-magnets-work-on/

I just checked my Cuisinart SS stick-blender shaft and my Kitchenaid SS stick-blender shaft. At first, I tried some of the magnets on my fridge and I couldn't get them to stick to either one. Then I got my son's super strong magnets that are as big and thick as hockey pucks, and they were only able to stick in one area of the stick-blender (right where it curves on the bell) The article I linked to explains why that curvy area can be able hold a magnet on certain items of stainless steel while other areas of the same piece of SS cannot. After that, I re-tried my refrigerator magnets and placed them in that curvy area, and there was a definite attraction, but it wasn't a strong enough attraction to get the magnets to actually hold on (they kept falling off).


IrishLass

 

[topofmurrayhill]

That article is pretty technical with the physics, but the bottom line is that some types of stainless steel aren't magnetic, and that includes some of the more corrosion-resistant types.

A magnet won't stick to the 300-series steels, which are used for a lot of things, including many (not all) of your cooking pots. A magnet will stick to 400-series steels. It's only a matter of which other metals are in the alloy.

You may find that one of your pots doesn't attract a magnet but it goes clang right onto your butter knife, and they are both steel. So a magnet will confirm that something is steel of some kind, but can't tell you that something isn't. It could be perfectly excellent steel.

 

[Willyd]

Stick Blender with Aluminum Splash Guard

Would you mind posting the brand and model of your stick blender? I'd like to know so I won't make the mistake of recommending it or buying it should I see it.

The stick blender I was using is a Bamix. They are very high quality, I have had mine for 20 years or so. Just don't use one to make soap right.

I ordered a new one from Amazon yesterday just to make soap with.

 

[Susie]

Y'all, I understand that theoretically a magnet test is no proof of stainless steel. However, I have had problems with "SS" that a magnet does not stick to. I have never had a single second of a problem with SS that a magnet sticks to. I am going to stick to my test, and until/unless someone can give me a simple test that anyone can do without a professional lab, I am going to continue to mention it when someone has an issue. Y'all are just going to have to forgive me.

 

[Arimara]

The stick blender I was using is a Bamix. They are very high quality, I have had mine for 20 years or so. Just don't use one to make soap right.

I ordered a new one from Amazon yesterday just to make soap with.

Oy, yeah. Most of the models I saw on the first page were over $100. At that price, I would never dream of using them for soap. You may want to consider Hamilton Beach, Kitchen Aid or even the Proctor Brand (that cheapie one piece stick blender you can find in a lot of stores). Many of us have had good luck with those.

 

[topofmurrayhill]

Y'all, I understand that theoretically a magnet test is no proof of stainless steel. However, I have had problems with "SS" that a magnet does not stick to. I have never had a single second of a problem with SS that a magnet sticks to. I am going to stick to my test, and until/unless someone can give me a simple test that anyone can do without a professional lab, I am going to continue to mention it when someone has an issue. Y'all are just going to have to forgive me.

There are caveats to buying steel items to be used with caustics, but your method does a poor job of solving those issues, so you should include additional facts with your recommendations so that people can decide the best thing to do.

A magnet will not stick to austenitic steel like the 300-series because it contains chromium and nickel and is low in carbon. It is very common and is used to make a lot of kitchen items including quality cookware. Even modestly priced good cookware like Farberware is made with 300-series steel. This type of steel is very hard and recommended for corrosion resistance with many substances including strong bases.

A magnet will stick to martensitic steel such as 400-series steel because it contains chromium but no nickel and a higher amount of carbon, which gives it a different crystal structure. It is used for some kitchen items such as utensils, bowls and some cookware. It's not as corrosion resistant as 300-series steel.

Creating caustic solutions for soaping is a relatively extreme application for kitchenware. No steel is impervious, but ideally you want the 300-series steel if possible. You can probably get away with 400-series steel at reasonable temps and concentrations, but why not use the most appropriate material since it's easily obtainable?

The magnet test will guarantee that you are getting steel. It will also guarantee you are not getting the steel you ideally want.

I don't use any no-name stuff for lye applications. To make do without a lab, you want to buy a quality product from a reliable supplier. It should be sold as a stainless steel product, and preferably it should be stamped on the bottom with the grade of steel it's made of. In most cases it should be stamped 18/8, 18/10, 304 or 316 and a magnet should not stick to it.