Keeping warm in a winter tent

*You will live long, All!* I'm interested in the subject's methods, especially what material (fabric) is best use on a tent. I myself have a homemade (not made by me) hemispherical tent on a metal frame, the material is some kind of nylon fabric, and waterproof and breathable (1 half of the tent for protection from wind and moisture impregnated with an alcohol solution of BF glue). I remember hanging out with a friend in the spring river, at night it was -10, but in our tent there was a clear plus (about 2-3 degrees It held up very well, because the water in the tent did not freeze). As 8 candles were used as a heat source and dry fuel was also occasionally burned (at the moment the tablet burned, the temperature generally jumped, but after it combustion did not last long). Without candles the temperature will be in just 5 minutes leveled out to the street level. And there was a slight sip of cold from the walls, although, as I I already said that we achieved some (and actually quite good) comfort achieve. Not long ago I overheard a conversation between two of my friends, from where I learned that It turns out that the ideal material for a tent is some salt bags (50 kg), which is sold by weight in stores. (???) One even stated that his tent was made from just such bags and this keeps heat normally, does not get blown through or get wet... Check andI was never able to clarify this matter, because that comrade “jumped off”, and It's a bit difficult to get it out. And back in the day, in a sporting goods store in E-burg, I saw a “winter” tent, where on top there was some kind of waterproof lining in the Bolognese style, and under it, inside - padding on padding polyester. This thing cost more than 5 thousand. /That’s all, All, what follows is only the truth.../