I took your advice and did a search. I found many alternate CARRIED tinders that people use with the spark-lite, nothing really about impromtu tinder that could be used in either an urban or wilderness environment and that had been tested with the spark-lite. I guess I need to backup and learn the basics of starting fires with tinder now. Pyromania is good...
Yah, I think you have a couple of different questions here. One about creating your own carried tinder of which there has been a lot of discussion; Which manufactured one is best, and lots of how to make your own.
Personally, I'm partial to the WetFire tinder by Ultimate Survival, who unfortunately recently went out of business, although there does appear to be at least some product still in the channels.
I found it burns well and it kind of melts and merges with the materials near it. As such, you can often use a very small bit of the material in conjunction with some small twigs, needles or leaves.
But you have a good point that there is much less discussion about improvised tinder.
Obviously that will depend a lot of your location and situation. In the Pacific Northwest, finding things that will burn isn't a problem - but finding dry materials.
If things are dry, it is a lot easier. I think one of the keys is to "fuzz" your tinder. For example, if you have some dry grass, break up the ends into fine strands. You should also be able to "fuzz" items including wood with your knife, held perpendicular to the item your are fuzzing.
There is also talk about using "fluffy" seed pods and while you sometimes encounter stuff like that here in the NW, it depends on where and when you are.
Of course you also asked about how the Spark-Lite tinders are made. As your wife points out, the material itself isn't overly sophisticated, but I recall they are impregnated with a couple of materials which is soaked all the way through. Perhaps someone who remembers can comment on what they are.
Also, the different fire starters work to different effect. My recollection is Doug has done some reviews that you should be able to find from the Equipped home page. I don't recall how well the Spark-lite performed, but I do recall that they all have different attributes to be considered. Personally, I have never used the Spark-lite, instead opting for the Swedish Firesteel, "Scout" model and the back of my knife.
You also hit on an other important issue. You want to practice ahead of time. Some people don't have much experience starting fires at all, and even with a match or lighter, much less using wet materials and only a sparker.
You want to build good working skill building fires, identifying and gathering tinder and becoming familiar with the attributes of the equipment you carry.
-john