redistilling smartstill

[goinbroke2]

Hold on guys, I think some clarification is in order here.

As Jimmy said, what's left in the still is known as backset.

You use this when your starting your next wash as some of the liquid. (replacing some of the total water amount) The reason you do this is the really low PH level which the yeast like and the "sour" flavour it adds to the wash and end product. (sour mash whiskey)
So, do you redistill the backset? no, here's why.
You take your wash at 10-15% and strip it down until you have about 20% coming out of the still.(starts about 60-70% drops to 20%) What's left (dunder) you chuck as it's all the crap that was left over from an initial wash. Do that until you have enough strip runs to fill the still. (each strip run will be about 40-60% average)

Then you do a spirit run down to 20% and what's left over is backwash and is basically water/alcohol only as the strip runs took out most of the crap. This 20% backwash you dump in your fermenter while hot and add your sugar and stir in.(inverts the sugar) Then add cold water and rest of grain bill. This will give the "sourmash" flavour.
Now, rereading the original post on this thread;

"I am re distilling 4 ltrs of 40% spirit. It has run off about 2 ltrs of combined 70% after throwing 100ml of heads away. now my question is in the still is aprox 2 ltr of leftovers i have used the spiritomiter and found it to contain 25-30% alcohol can i add this to my still in the next wash.

Dave "
Why would you redistill it? Instead of stopping at 20%, just run it down to 2% or whatever. The reason you stop at 20% is the same reason you would not redistill it, to much time/heat required for the last little bit of alcohol.
I forgot to add, not sure but the hydrometer wouldn\'t read right so it\'s probably not 20%. There is a difference between a beer hydrometer (reads from 0-24% or so) and a spirits hydrometer. There is too much crap left in the still normally to get a true reading regardless.