There is a scene in Dragon’s Ridge where a torch is lit, and the timing matters. While writing the scene, I had a nagging suspicion that the timing may be off, making the scene not plausible. But I had an idea on how to make the torch light fast, and I tested it with a homemade torch.
Tallow (rendered beef fat) was the cheapest fuel around in those days, available as a byproduct of food production. Cloth soaked in tallow takes time to light. At room temperature, tallow is a buttery solid. To burn, it has to be in a gaseous phase so it can mix with oxygen. Liquids and solids do not mix with gases. The solid tallow has to absorb enough energy to heat up and go through 2 phase changes. That takes time. Once the tallow is in gas phase, it diffuses out, mixes with the oxygen and burns. The oxygen also diffuses toward the tallow. Where fuel and oxygen meet is where the burn takes place. This is called a diffusion flame, the same kind of flame on candles and oil lamps.
Hollywood sometimes shows fast-lighting medieval-style torches, but those are probably soaked in gasoline, alcohol or some rapidly evaporating fuel. The problem with this kind of fuel is that one has to use the torch soon, or the fuel will evaporate away. I don’t think they had it in 11th century Gascony.
Is there a way to quickly light a tallow torch? Was it feasible to make in the Early Middle Ages? Yes, and this is how I did it.
Making a medieval tallow torch
Caution: Fire is useful but dangerous. Please use some sense and don’t start an uncontrolled fire. Keep plenty of water nearby. Wild fires are much more destructive in today’s changed climate.
First, I collected some beef fat and rendered it over low heat until no more fat melted out. It took an hour or two. Here’s what it looks like with the left-over meat removed: 
. (The black flecks are parsley. They wouldn’t hinder the torch.) The torch handle is a branch I saved after trimming a tree. I waited too long to make the torch because I was trying to get my book out. The branch became kind of dry and prone to burn too quickly. I soaked it in water for a few days to restore some moisture. 
It’s important to use fresh, wet wood that won’t burn through and drop the flaming torch head, creating a dangerous, messy situation. To soak up the tallow, I used an old t-shirt, spiral-cut into a long strip, like this: 
I warmed the tallow just enough to liquefy it, then fed the cloth strip in until it soaked up all the tallow. 
I found chopsticks handy for this. I wrapped the tallow cloth onto the tip of the branch. 
I kept the cloth as flat and neat as possible, suspecting that a twisted cloth may have trouble staying on when burned. I had to get my fingers dirty after a point. 
. I put some tension on the cloth for a clean, tight head. 
. Again, I’m not sure if that helps or hurts.
My idea was to wrap the tallow cloth with a dry cloth that serves two purposes. First, it keeps the grease contained during storage and transport. Second and more importantly, it provides a dry layer to help light the torch. The dry layer catches fire easily. It doesn’t burn long, just long enough to bring some tallow to gas phase. By the time the dry cloth burns out, the tallow cloth will be lit–hopefully.
As it turned out, there wasn’t enough tallow for my whole strip. The end of the strip was dry, so I didn’t have to use a separate cloth for the dry wrap. Here’s the final torch head, neatly tied up: 
.
The dry wrap lit easily as expected. The flame dimmed as that cloth burned up then brightened again as more tallow became available for burning. 
A torch like this should burn about half an hour to an hour. Toward the end, it dimmed because the thickening layer of burned cloth between the tallow and oxygen slowed down the diffusion.
Playing with fire is risky. Lucky for me, a firefighter happened to be in the neighborhood, collecting candy. 
I felt pretty safe having him there to back me up.