Sodium Hydroxide

pnance · Jul 30, 2007

I have been used empty soda pet bottles for chemical storage, they work well, theyre flexible and have great resistance to gas permability.

Mixing up some thiourea toner, I mixed the sodium hydroxide and after cooling stored it in a 2L bottle. Sometime later, when using the chemical, I noticed it was leaking. Draining the bottle, I could see that it was etched. And a large part of the bottom was cracked. Even though I used plastic to avoid etching a glass bottle, it would be safer than to use another 2L pet bottle.

I have seen many recommendations to use store NaOH in plastic bottles, has anyone else seen anything like this.

jim appleyard · Jul 30, 2007

Yes. I've had sodium hydroxide etch a plastic mixing beaker while making Rodinal. I may mix in plastic, but store everything in glass. I doubt SH would etch glass.

Rich Ullsmith · Jul 30, 2007

If you can get a nearby medical clinic or vet clinic to accept a small recycle bin, those liter plastic bottle that sterile water comes in are perfect. I've had an NaOH solution in one for a year with no problem. These bottles are graduated, slightly compressible, and you don't even need to wash them before using. Excellent seal on the cap, too.

titrisol · Jul 31, 2007

For palstic: Nalgene

Otherwise use glass, but be careful when soda solidifies in the lid it can become rock hard.

pnance · Jul 31, 2007

Actually was only commenting about the etching. Etching glass however is documented, see Wiki for example.

The problem was the cracking and resulting hole in the bottom of the bottle. See pic 2. It could be the 5 dimples and crystal formation causing the cracking. Any comments.

AgX · Jul 31, 2007

Titrisol,

Nalgene is a brand name. And not very popular here. In vain I tried to find out which material you mean.
Polycarbonate? Or HDPE?

AgX · Jul 31, 2007

I was surprised by that bottle breaking. I looked up some lists on the stability of PET and I learned that it is somewhat resistant against weak alcali but non-resistant against strong alcali!
These lists are often not very practible, but what I learned make me think that PET should not be used in the darkroom.
Beside the issue of storing a real hazardous chemical in a drink container...

Fanshaw · Jul 31, 2007

Sodium hydroxide in plastic bottles

Sodium Hydroxide is OK in some plastic bottles, but not PET plastic. I buy sodium hydroxide in plastic containers.

pnance · Aug 3, 2007

Titrisol: Checked Naglene web site, their info states "Chemicals can affect the strength, flexibility, surface appearance, color, dimensions or weight of plastics. The basic modes of interaction which cause these changes are: (1) chemical attack on the polymer chain, with resultant reduction in physical properties, including oxidation; reaction of functional groups in or on the chain; and depolymerization; (2) physical change, including absorption of solvents, resulting in softening and swelling of the plastic; permeation of solvent through the plastic; dissolution in a solvent; and (3) stress-cracking from the interaction of a "stress-cracking agent" with molded-in or external stresses."

This would make me hesitant to use it. I will use glass.

Photo Engineer · Aug 3, 2007

Sodium and Potassium Hydroxide will etch glass, depending on concentration. It will react with many plastics made from esters. It will not react rapidly polymers such as PVA (poly vinly alcohol) but it can make the sodium salt of the alcohol. Poly styrene and other similar plastics are rather resistant to plastics.

There are hardened glass lab containers made for this type of tough job.

PE

Marc . · Aug 3, 2007

pnance , a method to recycle PET bottles is to cut them in small chunks and then dissolve in Sodium Hydroxide...

Store Liquid Sodium Hydroxide in PVC bottles, labeled '3'

Rubber and PVC are the advised protections when manipulating Sodium Hydroxide solution.
I quote here a european Sodium Hydroxide producer www.belgochlor.be .

Marc

pnance · Aug 5, 2007

Greatg reply, thanks Marc.

GeoffHill · Aug 6, 2007

A long time ago, we used to store anythig that was a bit nasty, like Sodium Hyroxide, and Hydrochloric acid in PTFE. I've no idea where you would get ptfe containers, however.

Fotohuis · Aug 6, 2007

PTFE is Teflon and these type of containers are really expensive.

Sodium Hydroxide

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