Empty lye container - now what?

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Hi soapy friends,
This might sound silly, but what do you do with your empty container that your lye came in? I am sure it still has lye residue in it, so I don’t think I should just put it in the recycle bin. I checked the local hazardous waste place and they don’t list lye and I bet taking it there is overkill.
So before I end up with several empty containers sitting around, I’d really appreciate your thoughts.
Thanks 🌸
 
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In addition to the good rinsing recommended by @dibbles, you can also let the container air dry. If you see any white residue, that is just soda ash, aka sodium carbonate, aka washing soda. That's what happens to NaOH when it is exposed to air, and why you have to keep the container tightly closed to avoid having your NaOH become degraded. So after a good rinse and an air-drying session, you can rest assured that you won't be putting anyone at risk by placing it into the recycle container.

Another option is that some soapers cut off the tops of the containers to make them into cups for mixing soap batter with colors, and the like. :)
 

Marsi

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Old plastic lye containers go for plastic recycling or re-use.
These containers are strong and made from resistant plastic (#5, PP or poplypropelene).

The lye is hygroscopic (it will take on water from the air).
It does this very quickly (leave a teaspoon of it in a container for a few minutes and looks at how fast it turns into a liquid).

Rinsing is good.
It is possible to get a thin crust over caustic liquid after it dissolves, but before it full converts to other (way less harmful) chemicals.
(a very short-term problem - rinse and air-dry and the contain is safe)
 

DeeAnna

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Some containers used by suppliers for dry NaOH are PET (polyethylene terephthalate) plastic, not polypropylene (PP) or polyethylene (PE). PET is water clear, unlike PP and PE, so the clarity of the plastic container can be a clue if you're not sure.

PET is fine for DRY alkali, but it is not resistant to alkali solutions (NaOH or KOH mixed with water). It might be tempting to reuse containers to store alkali solution (NaOH + water) but if the container is PET, please don't. It will become extremely brittle and shatter in a very short time (days).
 

Marsi

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Some containers used by suppliers for dry NaOH are PET (polyethylene terephthalate) plastic, not polypropylene (PP) or polyethylene (PE). PET is water clear, unlike PP and PE, so the clarity of the plastic container can be a clue if you're not sure.

PET is fine for DRY alkali, but it is not resistant to alkali solutions (NaOH or KOH mixed with water). It might be tempting to reuse containers to store alkali solution (NaOH + water) but if the container is PET, please don't. It will become extremely brittle and shatter in a very short time (days).
Good to know ... I don't recall ever seeing lye in PET bottles here, so thanks for the additional information on container plastic where you are :thumbs:
 

TheGecko

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Hi soapy friends,
This might sound silly, but what do you do with your empty container that your lye came in? I am sure it still has lye residue in it, so I don’t think I should just put it in the recycle bin. I checked the local hazardous waste place and they don’t list lye and I bet taking it there is overkill.
So before I end up with several empty containers sitting around, I’d really appreciate your thoughts.
Thanks 🌸
I spray a little vinegar in them to neutralize any lye, then rinse in hot water and toss them in the recycle bin. Haven't had any issues in three + years.
 

Marsi

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Ok so that’s how to get rid of the empty container, but now how do i know if my lye is still active? I haven’t made soap in a while…
If the lye is lumpy, it has taken on some water and will weigh heavy (your superfat will be higher) - lightly lumpy and I'd still use it (and drop the superfat by about 1% - titration would be needed to check it properly)
If the lye runs smoothly, the lye is good.
 

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