Lye water/Oil temp question

[Forster]

Okay, probably a stupid newbie question but can somebody explain or point me in the right direction regarding the relationship between lye water temp, oil temp and the saponification process.

The books all tell me to let them cool off and and reach approximately the same temp between 100-120 degrees... but not why and what can happen if you don't follow this rule. Surely there are some impatient soapers out their that said heck with it and dumped 170+ degree lye water into 100 degree oil.

Does it ruin the soap? Is it dangerous? Will your soap seize up, get lumpy?

 

[Obsidian]

When I first started soaping, I religiously tested the temps and always got the oils and lye within a few degrees. Now I don't worry about it as much. I do like to have the temps under 150 but I don't care if one is cooler then the other.
The only exception is if I'm using milk or beer, then I make sure both oils and lye are under 110 so the batter doesn't overheat and scorch.

 

[jenneelk]

Seizing can happen with higher temps.. And I've had it happen to me in the beginning when I got impatient. Its also why people who want to do intricate designs not only work their recipe around a slow trace but also soap cool.. It slows the process down. And as you likely know.. The heating up after pour speeds up saponification so temp high equals faster chemical reactions. at least that's my interpretation of everything.

I now only soap at 85-95 but up to 110 on things like bastile or my very slow slow tracing ones.
Oh an I don't worry much about differences so long as both are under 110.