I was recently at a restaurant in Boulder on assignment for a magazine, writing about the chef and his approach to cooking (more on that and a GF review of the restaurant after my article comes out). After dinner, I sat at the bar chatting with the bartender, who makes many of his own liquors - amaretto, triple sec, sambuca, and more - from scratch. To oversimplify the process, he does it by making infusions...of almond for the amaretto, of orange for the triple sec, and of fennel for the sambuca. (The amaretto and triple sec were good. The sambuca was exceptional.)
The base for the infusion is Everclear, a neutral grain spirit. Neutral grain spirits are a class of alcohol characterized by their clear, colorless, and flavorless qualities. They also have very high concentrations of ethyl alcohol (ethanol) - we're talking very high concentrations, on the order of 150 to 190 proof. Taken straight, this stuff is like jet fuel and can do serious bodily harm. Used for a higher good though (such as an infusion), and neutral grain spirits have a rightful purpose.
Within the GF community, products like Everclear have typically raised a red flag, and they've been widely debated about whether or not they're gluten-free. First, it's worthwhile to note that Everclear is sold in two strengths: 190 proof (which is banned in some states), and 150 proof (sold where the higher proof is outlawed). The debate comes from the word "grain," and the fact that neutral grain spirits are typically derived (distilled) from cereal grain. I've already covered the ins and outs of distillation here, so I won't belabor that point. It's also worth noting that corn happens to be the most common grain used for neutral grain spirits, so there's no gluten to be concerned about in those instances.
To be doubly sure, I contacted the folks at Luxco, the parent company for Everclear. They confirmed that Everclear is derived from corn, and that their version of neutral grain spirits is gluten-free. So whether you're using Everclear for infusions of homemade liquors, or for other purposes, rest assured that it's gluten-free.