Unusual Lye Tank

[rcreger]

Hey everyone - I have a bit of a dilemma. I recently purchased a 5-gallon stainless steel milk can with a stainless steel spout from Shenandoah Homestead Supply with the intent of using it as a small lye tank. This is definitely an off-label use, their customers are dairy farmers.

My concern is the washers that were used with the spout. They appear to be made of soft silicone. I'm sure it's perfectly safe for milk transport, but lye water?

Does anyone have any experience with silicone washers making prolonged contact with lye solution?

Thanks!

 

[Marsi]

My first thought was to suggest that the silicone will not withstand prolonged exposure to a strong lye solution.

Tank makers (that make tanks for storing lye solutions) suggest EPDM gaskets.
Example:
https://www.protank.com/sodium-hydroxide

 

[TheGecko]

No experience per se, but we do use silicone molds which are in contact with Sodium Hydroxide.

Soapequipment.com makes lye tanks and their website says that they use 'special gaskets', but they don't mention what type. But under their FAQs, they do note that you can only store the lye solution for three to four weeks because of the gaskets...which tells me that you have to change out the gaskets. You could call and inquire...you could also do some experiments of your own. If it was me, I would purchase several different kinds of gasket material and then make up a small batch of lye solution of the concentration that I intend to store and then I would put each gasket in hard plastic dish with a few tablespoon of the lye solution and then start the clock...see what happens.

Did a little further research, ran across a website called ProTank: Sodium Hydroxide is also known as caustic, caustic soda, and liquid lye. We recommend that it stored in a HDPE tank that has a SG of 1.9. Sodium Hydroxide can also be stored in a XLPE. The recommended fitting material is PVC or 316 SS. Gasket material should be EPDM.

McMaster-Carr would be a good source for purchasing them...depending on your fitting...one to three bucks each.

 

[rcreger]

My first thought was to suggest that the silicone will not withstand prolonged exposure to a strong lye solution.

Tank makers (that make tanks for storing lye solutions) suggest EPDM gaskets.
Example:
https://www.protank.com/sodium-hydroxide

Thank you for that link, it was quite informative!
I also emailed Shenandoah Homestead Supply and they confirmed that the washer for the spout is indeed silicone, and the stem of the spout is 16mm in diameter.

I found FDA compliant EPDM washers at McMaster-Carr and ordered some.

 

[Marsi]

Awesome find!
(and the fastest upgrade/fix I've heard in a while 😆)

Have you been able to source/engrave safety labelling for the vessel?
(I get very nervous if lye solution goes into anything that remotely resembles a food/drink container personally 😬)

Photo's please (bragging rights - I think you've got the makings of a great tank!) 😍

 

[TheGecko]

Have you been able to source/engrave safety labelling for the vessel?

I would NOT recommend engraving.

 

[Marsi]

I would NOT recommend engraving.

Noted. Why?
(It would need to be colour-filled for visibility/safety, but I am not sure of your reasoning and would be interested to know what safety concern you have with this approach )

 

[rcreger]

Awesome find!
(and the fastest upgrade/fix I've heard in a while 😆)

Have you been able to source/engrave safety labelling for the vessel?
(I get very nervous if lye solution goes into anything that remotely resembles a food/drink container personally 😬)

Photo's please (bragging rights - I think you've got the makings of a great tank!) 😍

I don't have any pics of my own yet, but this is it on the Shenandoah Homestead Supply website. https://cdn.shopify.com/s/files/1/1871/4193/products/IMG_1261_1024x1024.jpg?v=1549386727
The stainless steel tap is a $29 add-on, which IMO is worth every penny if I don't have to do it.

I haven't put any labeling on it yet; I make soap in the basement of my 83 yr old mother inlaw's house. She lives alone and has no interest in what I am doing other than providing her with lots of free soap.

I also bring her dinner on the nights I come after work to work on the soap.

 

[Marsi]

Having the tap fitted for you is a bargain at $25, I agree!

(Safety label could be as simple as a large swing tag on one of the handles ... never know/just in case thinking)

Dinners and free soaps ... for a basement to soap in? What an incredible exchange, for both 😍

Can't wait to see the tank all set up - you must be excited?

 

[rcreger]

Having the tap fitted for you is a bargain at $25, I agree!

(Safety label could be as simple as a large swing tag on one of the handles ... never know/just in case thinking)

Dinners and free soaps ... for a basement to soap in? What an incredible exchange, for both 😍

Can't wait to see the tank all set up - you must be excited?

I am anxious to get it up and running to be sure. Right now I have 100 or so bars of soap I need to trim and box and a couple of other batches that will be ready in another week or so.

AND, I ordered a couple of molds from For Crafts Sake that should be coming in another couple of weeks. I am hoping to have this Milk Can/Lye Tank online and ready to go for the inaugural soap batch in the new molds.

 

[rcreger]

Update with pics attached. The EPDM washers are installed, and the Milk Can Lye Tank is in the shop.
I ended up buying two thickness sizes of washers. That was a good thing in the end. You can see in the second picture one is white and the other is black.