Lye first aid
Correct first aid for lye (NaOH or KOH) or raw soap batter on the body
Rinse with plenty of plain cool running water. If you don't have access to clean water, rinse in the nearest mud puddle -- but you have to rinse!
You have SECONDS to react, so MOVE FAST. The quicker and more thoroughly you get the lye rinsed off, the better.
Rinse for at least 10 minutes. Do not skimp on the rinsing. Even if the pain is all or mostly gone, that does not mean the lye is gone too. If the lye is not fully removed by rinsing long enough, it will continue to damage body tissues.
Remove contacts and contaminated clothing after washing off the worst of the lye. Start rinsing first, however, and deal with clothes or contacts later.
If the lye is under the fingernails or in other crevices, gently rinse, scrub, and clean those areas carefully to remove all traces of lye.
If the burn is in or near the eyes, nose, or mouth or is a deep or large burn, see a doctor or emergency room for treatment immediately after you have rinsed well with water.
Treat small, mild lye burns just as you would any second degree burn. Keep the wound covered and moist with a water-based product. Do not use oily salves, butter, or other fatty products on any burn.
Never, never, NEVER use vinegar on a lye splash anywhere on your body. Rinse with plenty of plain cool running water.
Why vinegar for a lye burn is a Very Bad Idea
Vinegar, an acid, does indeed neutralize NaOH or KOH, both bases, but there are serious downsides to doing this kind of chemistry directly on the body.
First, the your skin is already being damaged by the lye. NaOH or KOH quickly breaks down the skin tissues and releases heat. Alkali and thermal (heat) burn ... ouch!
Adding vinegar to the lye will trigger an acid-base neutralization reaction. This reaction releases plenty of heat. If you know how hot your lye solution gets right after you mix the lye with water, you know exactly what I'm talking about. Even more thermal burn ... ouch!
On top of that, the vinegar itself, being acidic, will damage body tissues already injured by the lye and the heat. Acid burn ... more ouch!
All this damage results in intense pain and possibly a deep, slow healing wound.
To make matters worse, lye is a strong alkali and vinegar is a weak acid, so you need a lot of vinegar to completely neutralize a small amount lye. One ounce (2 tablespoons, 28 grams) of vinegar will neutralize only 1 gram of NaOH!
Cleaning up after soaping
If it makes you feel better to spray vinegar around your work area and to rinse your utensils with vinegar, then do so. You aren't going to harm anything by using vinegar on non-living things. If you do use vinegar for cleaning up, use it full strength so it can actually do some good. That said, just a good rinse with water is really all that's needed.
For cleaning soapy or oily bowls and utensils that may have active lye on them, I wipe the items with old towels to remove excess soap and oil residues and then rinse the items well with water. I use a synthetic detergent cleaner like Dawn and hot water to do a final wash.
The soapy/oily/alkali-covered towels go into a plastic bucket far out of reach of curious human hands and critter paws. Once the residues have had a day or so to saponify, the towels gets washed with dirty chore clothes.
Everyone has a favorite way of cleaning up their work area and equipment after soaping; this is just my method.
Cleaning up after a lye spill
For a small spill, sop it up with paper towels, newspapers, old towels, or the equivalent. For a larger spill, use clay kitty litter (the regular stuff, not the clumping kind) or wood shavings to absorb the liquid.
Put lye-contaminated items into a lye-safe container. Loosely cover the container, set it in a safe place away from pets and humans, and let the contents sit for a few days while the lye reacts with the absorbent material.
Wipe up any remaining residues from the spill with paper or cloth towels and water -- and be sure to rinse, rinse, rinse. If you also use vinegar to make sure all residues are neutralized, use it full strength so it will be the most effective.