As you see, the lye will turn the milk a light amber-orange color. It also will (briefly) give off a nasty ammonia-ish smell. This is normal. It will go away quickly.
You'll notice that the solution starts to thicken. This is the fat in the milk actually making "soap" with the lye in the lye solution. But there's not enough fat in the milk to make a whole lot of difference - just enough to thicken up the solution.
Note: Since we want to "scorch" the milk as little as possible, I usually let the lye cool down a bit more than normal...somewhere around 90 degrees.
