When making neutral spirit it is very important to filter the spirit through carbon as it removes a substantial amount of bad tasting contaminants. Personally I recommend using a fuselex carbon filter because they are made from stainless whereas a lot of other filters are made from plastic. Some plastics are soluble in alcohol, not something you want to be drinking!
To filter the spirit cut it down to 40% with water (use this calculator) and filter as slowly as possible through the carbon. You can filter 10-20L of 40% spirit through 300g of carbon.
If you do not want to buy a carbon filter you can age the neutral spirit on carbon for 2-3 weeks. Use 10g carbon per litre of spirit and shake the container occasionally.
Double distillation of you neutral spirit is the most important method you can use to improve the quality and quantity of your finished alcohol.
1. Distil your wash as normal, you do not have to discard anything as you will do it on the second distillation anyway. This is called a "stripping" run because you "strip" the alcohol.
2. Collect the spirit and dilute to 45% using the calculator found here
3. For every 8-10L spirit add 1 tablespoon of sodium carbonate (not bicarbonate). This is sold as washing soda at the supermarket.
4. Run the still as normal, discarding the first 50-100mLs. This is called the "spirit run"
5. Dilute to 40% and carbon filter
To save time you can strip the alcohol from two or three ferments and then do a single spirit run.
Tomato Paste Wash (or TPW) is a different sort of wash that is much cleaner than a turbo wash. Tomato paste wash has the downside of yielding less than a turbo wash but at the same time is much cheaper.
6kg sugar or 7kg dextrose
250g tomato paste
70g bakers yeast (or 15g EC-1118 yeast)
Add sugar or dextrose and tomato paste to the fermenter. Half fill the fermenter with water. Stir until the sugars have dissolved. Top up fermenter to 27L.
Sprinkle yeast on top and ferment at 25-35C
When gravity reaches .990 on your hydrometer transfer to the still and run. I make a 27L wash to ensure I definitely get 25L into the boiler.
Turbo wash is the easiest wash to make however due to the high alcohol content and the nutrient mix, the resultant alcohol can develop an off taste that many describe as akin to methylated spirits.
7kg sugar or 8kg dextrose
1 sachet of turbo yeast
Fill your fermenter with either sugar or dextrose.
Top up to 25L with water and stir until sugar or dextrose is dissolved.
Add turbo yeast and ferment at 22-35C
When gravity reaches .990 on your hydrometer transfer to the still and run