Guys, like others have mentioned, NEVER BUT NEVER mix caustic with hot water. I don't care what John says how he does it, someone will get seriously hurt sooner or later by mixing caustic with hot water.
Listen to Russ J., he is a chemical guy, has tons more experience than most here put together and would not post info to hurt anyone here ever.
If you have ever mixed caustic to a strong mix, you will feel how hot the container gets, mixing with hot water is stupid to say the least and that is a recipe for a serious accident waiting to happen. I don't know why he would mention that is why he mixes that way.....if he really even does mix it with hot water....., might just be trying to brag about something. I seriously doubt it, sounds like some mis-information to me.
I have had some serious hot water/steam burns where I burned all the skin off rmy hand before and that was not even using caustic, I would hate to have someone follow this bad advice on mixing caustic and get seriously hurt.
If you want to make home-brews, be very careful, use the proper ppe and mix with cold water....the mix will get very hot on it's own.
Always add the caustic to water, never the opposite as it can violently react and shoot out of the container and burn you, it is always a good idea to buy from a good and reputable chemical vendor like Russ J. and get his advice on mixing for strength.
Again, I would hate to see anyone get chemical burns from reading someone's advice here on using hot water to mix caustic, don't do it ever, why take the chance?