Lye and Zinc

D

Dan Farmer

Member
I have an old zinc lined laundry tub in the basement that I've been doing my cleaning in. Its about time for me to clean out my lye tank, but I see that lye and zinc don't mix. Lye won't attack copper or iron, but it will do a number on anything galvanized.

Any pointers on neutralizing the lye (lb to 5 gallons H2O that has probably evaporated to more like 4 gallons) with vinegar? How much vinegar, and will it generate too much heat for the plastic tub?

---------- Post added at 11:15 AM ---------- Previous post was at 10:08 AM ----------

I may have found the answer I was looking for: http://www.pburch.net/dyeing/dyeblog/C1845207367/E20100217131536/

Lye, also known as sodium hydroxide, or NaOH, is a much stronger base, which means that it all ionizes in water at once, leading to a higher pH than a similar number of moles of sodium carbonate in water. (A lot of the sodium carbonate in a solution remains unionized, which is why the pH doesn't go up above 12 no matter how much soda ash you put in, but the pH can go above 14 if you add enough lye.) One mole of sodium hydroxide in the form of lye weighs 40 grams, which is about 19 milliliters of the lye pellets that contain 99% sodium hydroxide, a little more than one tablespoon. Since one mole of sodium hydroxide reacts with one mole of acetic acid, this 19 ml of lye should react with 1200 ml or five cups of vinegar; one cup of lye pellets would be neutralized by about 15 quarts of vinegar. This is based on the assumption that the lye was already diluted in a large quantity of water when the dyebath was prepared. The reaction of strong lye solutions with vinegar could be extremely hazardous to be around, since the lye could be splashed about by the formation of bubbles of carbon dioxide.
Click to expand...
 
Dilution is simpler and less costly. If you're not on a septic system, you could turn on the cold water tap in the sink and, with the water running, pour your lye solution down the drain a half gallon or so at a time, and let the water continue to run for a minute or two.

Also noted at the link previously mentioned.
 
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