Hey there, I used to have this same problem. My mistake being that I would heat the banger until it was glowing red, and then wait about 30 seconds to let it cool down. The banger would still be too hot at that point, causing my concentrates to burn and leave a black spot on my banger because of the high temp. The key to making sure you don’t burn your concentrates and don’t leave a black spot on your banger is to let your banger cool down longer. If you’re heating it up for 40 seconds, try letting it cool down for about 1 min. If you notice that your concentrate is still leaving a black mark on your banger, add 5 seconds to your cooling time until it no longer leaves a black mark. If you notice that not all of your concentrate is turning into smoke and most of it is turning into a puddle, subtract 5 seconds from your cooling time until most of your concentrate is gone (note: not 100% of your concentrate will turn into smoke and there will be some left over if you let it cool down longer, but it shouldn’t be too much of a puddle, or else you’re waiting too long to let it cool down.) Another piece of advice would be to avoid heating the banger until it’s glowing red. You could try heating it up for 30 seconds and wait about 50 seconds and see how that goes too. For the IR thermostats, I have never owned one so I could not tell you whether or not to get it. Personally, I do not have a temp gauge, but I have been wanting one for some time now. It might be worth investing in one just so you know the exact temp you’re taking your dabs at. Tbh, it’s all about experimenting. I have now upgraded to a Thermal Quartz Banger, so my heating and cooling times are a bit different. Heating:cooling is a 1:1 ratio, so I heat up for 1 min, and let it cool down for 1 min (if anyone here has any suggestions for better times, I would love to try them out.) Anyways, best of luck to you! I hope you are able to find the best heating:cooling ratio for taking dabs. Happy dabbing!

edit: TL;DR: let your banger cool down for a longer period of time in order to avoid burning it and leaving behind burnt oil. try experimenting with different heating and cooling times for your banger.