I've heard that the nasties in the first part ("heads") are called aldehydes - caused by oxidation of alcohol, and that there are many types of aldehydes that can be released released into your white lightening, methanal is just one of them. It can be hard to judge what volume the "first 10%" of the yield will be, and the 10% thumb rule is not worthy of staking your eyesight on. I've heard that it could be as much as the first 1/3 or could be less than 10%, based on factors I'm not knowledgeable of. I saw a special on Dirty Jobs where Mike Rowe visited a small rum distillery where the guy had a big pot still. The guy said that you can detect the presence of Aldehydes with your eye. Aldehydes irritate your eyes, so he had a small tasting glass he would hold under the spout, catching samples and holding the glass up to his eye to see if it made his eye burn. When it stopped making his eye burn, he knew it was safe to drink and would start collecting it. The last bit I don't remember how to know when to stop collecting it.Yes theres actually books dating back to the 40's on how to do it at your public library. If anyone plans on distilling real liquor remember pour out the 1st 10% because that contains methenol and will make you go blind. You also throw out the last 10% because of contaminants and quality control issues. Then proof the 80% left with 1:1 water and your rollin. If you want white lightning drink it clear, if you want real whisky put it in a oak barrel thats charred inside for 3-12 years. The whisky will pull the caramels out of the char and wood turning the white whisky brown, you then have whisky or bourbon etc.. Use fruit instead of corn and suger and you have brandy. I'm about done building my still. Its not traditional, just need to find a 10-20 gallon pyrex pot, I've already got 5ft water cooled pyrex distillers.