A carb cap is a tool used to fully vaporize extracts at an exceedingly low temperature. These low temperatures provide smoother and more flavorful vapors which lead to a more pleasant smoking experience. Carb caps are usually made from titanium, ceramic, glass or quartz. They feature a hollowed, rounded end which forms the cap and a pointed end which often doubles as a dabber too.
When dabbing without a carb cap, oil is vaporizing in an open air system. An open air system means that the oil relies solely on the heat from the nail to completely vaporize and this can be seen when using a domeless nail, a curve or a banger. Open air systems require high temperatures that often except the boiling point and smoke point of the oil in order to reduce product loss. These high temperatures can also lead to a mixed flavor caused by the burned front end of the oil and the full flavor of the rest of the oil.
Adding a carb cap over the nail changes things drastically. Now you are focusing on a lower temperature dab. The carb cap works to create a chamber with a restricted airflow for concentrates to vaporize within. Most carb caps restrict the air intake to a single hole at the top. This hole is smaller in diameter than the one of the domeless nail which creates suction that lowers the interior pressure. The drop in interior pressure leads to a lower boiling point of the oil, allowing for complete vaporization. The small hole along with the suction and drop in pressure also work to create a vortex. The vortex works to cool down both the air and vapor inside and providing that smoother hit we mentioned earlier.
If you are interested in giving a carb cap a try the next time you dab, check out Excape Vapes Titanium Carb Cap Dab Tool.