The amount of NaOH or KOH depends on your ingredients and will be safe because the alkali will chemically react
. Check your pH! Besides, you’re not going to use as much as you’re using borax or your hair will turn into felt.
NaOH and KOH are safe to handle if you’re careful and follow a few rules:
Add cold water first, then the alkali, and mix carefully until dissolved. By preference, use enough water because dissolving these bases will result in considerable heat. A 1% solution will barely heat up whereas a 10% solution may get steaming hot.
Wear safety goggles, good goggles, and gloves. If some gets into your eye, goodbye. It takes a split second to permanently burn your cornea. On normal skin, rinse with a lot of cold water and you’ll be fine. Your skin will start to feel soapy should some cross-contamination get on your hands and you’ll know that it’s time to rinse your hands. Be cautious not to touch your eyes during your work because already a small indirect contamination can waste your eyesight.
Always close the container firmly. A: NaOH and KOH attract water and B: you don’t accidentally spill the whole container.
If you’re dissolving larger quantities, have a bottle of kitchen vinegar at arms length. Spillage of some litres of lye solution won’t just ruin your clothes but it might prove tricky to rinse yourself from tip to toe under the tap; using vinegar to neutralise the alkali can come in handy. Mind, this is not something you should do as a standard operation procedure especially not with your eyes (you don’t want to acid burn the remaining bit of eye you still have after an alkali burn)! Having that bottle nearby (and open or it’s useless
) is more of a psychological thing which calms your thoughts and fears and hence steadies your hands -> goal achieved without actually using it!