When is the right time to put stuff in and about metal with soap?

[MickeyRat]

I've been making soap for a little over a year and I'm stil not certain about a few things. I've been putting TD in my oils before I even dump the lye and that works fine. I've already seen opinions that say that waiting for trace to put in your overfat in CP is hooey. I've also seen a few people that say that mixing a castor oil with your scent and dumping at trace will make the scent hold better. That sounds like hooey. Still since my overfat is usually 5% castor oil, I mix it with the scent and dump at trace. Assuming it's not an accelerating scent, is there any reason not to put everything together at the beginning and go?

The next question is about metal in contact with curing soap. I only recently heard that might be a problem. Several months ago, my son-in-law made me a rack to cure my soap. The soap is sitting on 1/4" hardware cloth (like heavy duty chicken wire with 1/4" square holes). I've cured a fair amount of soap on it. It works great and I'm not seeing any ill effects. Am I missing something?

 

[Saponomancer]

Yeah, there's no reason not to put it in at the beginning, with cold process there's no telling what your superfat will end up, and there's some evidence that it doesn't even matter with HP when you can put it in after the cook.

Metal *can* make your soap go rancid, before I started including a chelator with my soap I found that the metal cooling racks I was using then left orange stripes on the bottom of my soaps- DOS, they had gone rancid everywhere they touched the metal. If I recall correctly it has to do with metal ions, but I don't remember the exact explanation.

 

[TAS]

I mix everything into my soap pot before the lye. I like to stick blend the "stuff" in my pot a lot before the I pour the lye in.

 

[IrishLass]

Yep- assuming that the FO is not an accelerating one, you can add it (and the castor oil) up front. Ever since finding out that adding superfats at trace is much ado about nothing, I add all my fats together up front, and if my FO is one that plays nice, I add that up front, too.

For me, none of the 'tricks' for making a scent hold better has worked. What has worked for me is reading scent reviews and using a quality FO that has a reputation for being a 'sticker' all on its own.


IrishLass

 

[DeeAnna]

Some metals are worse than others for triggering rancidity (DOS). Copper and iron are biggies. The galvanization on your hardware cloth is zinc, and that's lower on the list of culprits, but still of concern. I personally avoid storing soap on any metal based on the findings in an interesting study published in 1922. The authors reported on their experiments about the causes of rancidity in fats. Soap has the same triggers as plain fat, IMO.

Here's my outline of their findings that is relevant to this thread --

Copper accelerated rancidity the fastest, but it was followed fairly closely by lead and iron. Zinc fell in the middle and the slowest was aluminum and tin. The researchers pointed out, however, that lard stored with any metal, including aluminum and tin, became rancid faster compared to lard stored in plain glass. The researchers also noted that "...Light was necessary for the development of rancidity in fats exposed to air but not in contact with metals. Fats stored in contact with metals developed rancidity even when protected from light...." Source: James A. Emery and R. R. Henley, "Studies on Rancidity", Journal of Industrial and Engineering Chemistry, 1922. (14:10, pg 937-400)​

My conclusions for soap making --

A small amount of metal contamination in our fats is unavoidable, since fats are processed using metal equipment. To prevent additional contamination, however, use plastic or glass containers for storing and working with fats and soap. Use silicone utensils whenever possible. Stick to stainless steel utensils when metal must be used. Avoid using water that may have a high metal content. And consider using a chelator such as sodium citrate or tetrasodium EDTA in soap to immobilize stray bits of metal.​

 

[HowieRoll]

Regarding the metal, a few months ago I had a whim to try an old hotel soap I'd saved (it was new in the package, but several years old). I used it a few times and then put it on the metal shower caddy on the top shelf. The other day I noticed it was completely yellow and had gone rancid. I guess the moral of this story is it managed to not go rancid for many years, and then I think being in contact with the metal triggered the DOS within a couple months. To be on the safe side, if it were me I would line the hardware cloth with something non-metal so as not to tempt DOS fate.

(and I see DeeAnna has replied with great info, as usual, while I was typing up this reply!)

 

[dibbles]

I had some stainless cooling racks (baking) that I put some bars I made for testing FOs on. Like TheDragonGirl, the soaps developed orange lines where the metal was touching the soap, and it happened quite quickly. I don't know if it was not truly all stainless or poor quality stainless, but after that I'll put a cloth or some plastic mesh between the metal and the soap if I ever need use them again.

 

[MickeyRat]

Thanks for the replies folks. I actually have a rather sad looking bar from my first batch sitting up there that's over a year ago. Though I haven't had the rack that long, it's been up there since I got it. Most soaps get moved off the rack to cardboard boxes after 4 to 6 weeks that might be why I'm not seeing any ill effects. The rack isn't that big.

I seem to remember seeing some kind of plastic sheets I could use to cover it on here. Hopefully, I can find that post again.

 

[cmzaha]

I do not ever consider it a right time. I advise my customers to not even use stainless steel soap dishes or set them on the shower racks if metal.

 

[MickeyRat]

I think I've found what I need. I can get knitting canvas on Amazon. For less than 10 bucks I can get enough to cover that hardware cloth.

 

[DeeAnna]

That's a good choice, @MickeyRat. It's sturdy and lets air flow through.

 

[soaring1]

You could also go to a hardware store and get sheets of plastic light louvers and cut them to fit your shelving. Easy to clean.

 

[earlene]

I think I've found what I need. I can get knitting canvas on Amazon. For less than 10 bucks I can get enough to cover that hardware cloth.

That's what I use to line my curing trays. I have been fortunate enough to find great prices for them at Goodwill stores two or three times. But they're pretty inexpensive at Walmart brand new.