You can buy both (or used to, anyway) at Essential Depot. I don't think there's a big difference in price.
The point about using "food grade" ingredients is that they're intended for use in food. Food grade standards for heavy metals and other contaminants are determined to protect the quality of food, especially food consumed by children who are more sensitive to heavy metal contaminants than adults.
Soap doesn't get eaten -- and we only use a few grams of soap per day. Compare that to the weight of the food and water we consume.
If it makes you feel better to use food grade NaOH and you have a reasonably priced, reliable source, then by all means use it. If it's hard to find or the added cost is going to break the budget, then tech grade is plenty fine.
The point about using "food grade" ingredients is that they're intended for use in food. Food grade standards for heavy metals and other contaminants are determined to protect the quality of food, especially food consumed by children who are more sensitive to heavy metal contaminants than adults.
Soap doesn't get eaten -- and we only use a few grams of soap per day. Compare that to the weight of the food and water we consume.
If it makes you feel better to use food grade NaOH and you have a reasonably priced, reliable source, then by all means use it. If it's hard to find or the added cost is going to break the budget, then tech grade is plenty fine.