BC ICC era Firecracker Fuse Question

[FinnAmerican]

I have some ICC Class C (1"&1/2") Black Cat logo Firecracker Singles. All of them have a orange color residue on the paper fuse(image doesn't pick up the color too good)
Anyone here know what it could be?. I didn't know if there was a powder or chemical added to the fuse. Just curious.
I also have some (1"&1/2") Singles from the early 50's but no colored residue.
6785

[gweilo]

Although I've never seen such orange fuses, I think Halk mentioned in another thread that for a while the factories were adding some potassium dichromate to the fuses. Potassium dichromate is a very bright orange color, an oxidizer, and very toxic to humans (don't lick the fuses). I don't know why the factories ever used it, and they didn't use if for long if they did because I'm sure factory workers became ill at some point. Potassium dichromate as an oxidizer might've added a little zip to the fuses, and it won't absorb atmospheric moisture so the fuses would remain dry. And poisonous.

[halk]

Yeah Dr. Lai mentioned that in his book. Chinese also tried all sorts of additions to black powder over the years. Have some very old One Thousand Blessings crackers from Taiwan that I can clearly see crystals of A2S3 "Chinese Needle" in the mix.