Will sugar in the rub burn at 250 F?

I used a rub recipe that was 60% brown sugar and white sugar, and had it in my electric smoker all day at 250F, and I could swear it burned the rub before I basted it 6 hours in. It was almost black at the time I put the sauce on....I was going to do a crutch with the sauce inside the foil but got lazy and brushed the sauce on the top side and left out the foil wrap. Cooked another 45 minutes. The crust tasted burnt and was pretty much black on both the top and bottom.

Does sugary rub burn at 250F? Will 220 or 210 be better if I want to try this new rub recipe again sometime? Thanks!

I do need to invest in a good thermometer to see how honest the temperature dial setting is on my electric smoker. I heard a rumor that this brand has a tendency to vary it's actual temperature alot....large temperature swings. So maybe it could be a hotspot because it looks like all the ingredients on my list shouldn't burn at 250 according to the experiments done by bigabyte.

thank you bigabyte, have you ever done this experiment mixing several ingredients together to see if some kind of reaction took place between them causing them to burn? Or perhaps have you tried pork fat in the presence of these ingredients to see if the heated fat reacted with the ingredients to cause burning? I might try to just sprinkle my rub and place in 250 degree oven for 6 hours to see what happens, and also try that with some pork fat sprinkled with the rub to see if there is a difference. Hmmm, now did I take those trimmings out to the trash already tonight?

Well the wood I'm using are small 2inch long by 1inch cylinders of barkless hickory...and I only use 1 per smoke because it gets so bitter (this electric smoker really traps in the smoke), I bought the hickory from the smoker manufacturer, the color of smoke is hard to tell right now because it's so cold outside the steam coming out of the smoker is almost more intense than the smoke, the usual color of the smoke from last summer/fall was a light grey as I recall. I have had much better batches of ribs or brisket in the past, it just seems like something went really wrong with this batch causing everything to turn black and burnt.

Oh they were done, almost fall off the bone done....and they were probably done at 6 hours, well they were black on both sides already when I put the sauce on, well, it was kind of dark outside so they looked pretty dark from what I could tell with my meager porch light...dang it gets dark early this time of year. Anyways, next time I won't put the sauce on for so long like I did for a whole 45 minutes with no covering. What I should've probably done was put the ribs on foil at the 4 or 5 hour mark, pour some sauce, spiced rum on it and wrapped in foil for a crutch. Well my temp dial maxxes out at 250 F, I can't set it any higher than that.

As for Alton Brown, he has a salmon rub that is really tasty, just a couple ingredients if memory serves, just some black pepper, salt, and brown sugar/white sugar. There is something to be said for keeping it simple. The red western alder gives it the most amazing flavor I've ever had on smoked fish of any kind. Some guy on amazon was selling colorado alder which is not the same (I think it's officially called white alder if memory serves). The red western alder is better and it likes to grow near ocean moisture like on the West coast, so I had to order it from just smoked salmon, they were some furniture shop leftovers cut to nice small rectangles. Pretty expensive to have a bag of wood shipped across country but my smoker is very efficient and doesn't need very much wood to give a good strong smoke flavor, just a tiny piece really. I think $25 got me a lifetime supply of the stuff considering I don't have salmon but once a month. I haven't had any problems with smoking in this tight box until last night, all my other batches were fine up until the last one, so I think I may have either had the temp set too high, the ribs in a hot spot, or just plain cooked the sauce too long.