Q about residue on nail after vape hits of ISO

ive made 3 batches of ISO/QWISO oil in the past and all 3 batches have came out the same. the only variable was the different medicine that was used. 1st go was keif and a 1/8th of medicine. 2nd time was a 1/2 of fire meds, the 3rd was 15 grams of dry ice and bubble hash from the same fire meds, and netted me 4.3grams of oil. All 3 times ive used the same tek using 99% iso, frozen material and iso, 20 sec washes, hot water evaps, then on a griddle set at 170* for about an hr with a hot pad under the glass pyrex work dish. the oil in question when pulled on my dabber always has a nice tail that slowly retracts, and has a nice amber color when thinned out or pulled.

after hitting the oil on either my glass or ti nail (or another small oil pipe), im getting this black residue left over. there is not too much discussion of residue after oil hits, so here we are. the oil is super potent. 2 nice rips and im good for 5+ hrs. im wondering if this is the norm with iso? Im leary of making BHO, as its a little too volatile for my liking. but it sure does look awesome!!!!



thanks everyone.

Its normal for any hash concentrate...or really almost any substance..it doesn't evaporate or burn completely...especially with increasing carbons/chain length

Soooo I wasnt really talking about this but quote still applies..hopefully helps
"When wood is heated anaerobically, it turns black as the water is driven off, leaving charcoal, or carbon, behind. When charcoal burns in air, the carbon combines with oxygen, producing carbon dioxide gas. But if you have ever used a charcoal grill,you will noticed that charcoal turns white as it burns. This white ash is what remains of the non-flammable minerals which were present in the wood to begin with. You don't really notice them until the carbon has burned away. These ashes have a composition which varies according to the kind of wood and the soil in which it grew, and it is this variable composition which marks ash as a mixture rather than a pure substance. Hope that helps with the color of ash confusion

that anaerobic burning is what causes butane lighters to produce soot or that black stuff if you put the flame under something, propane burns wonderfully clean but as you add carbon it needs more oxygen, as you go up it won't burn properly unless you add an oxidizer.. this is also why BIC lighters are only about 500 degrees instead of 3500 or whatever butane likes to burn at..(bics design limits oxygen, if you have a torch for dabbing with an adjuster you know what I'm talking about)"


That black stuff is carbon from it not being able to burn properly...it may turn white overtime with more heat

thanks

I do use a torch to light the nail with.

Dayem qwis the breadth of your knowledge is impressive... Keep droppin science. I get that black crap on my quartz nail too. I thought maybe my oil was low grade even though it tastes good & seems to work ok. Alcohol seems to clean it right off though it leaves a milky residue... Can't seem to get my quartz nail to clean up clear as the day it was new but hits like a cannon.