The second hole on your pipe is called a carb (short for carburetor), and it controls airflow. You cover it with your finger while lighting and inhaling, then release it to clear the smoke from the chamber. Once you understand this simple cover-and-release rhythm, smoking becomes smoother, cooler, and far more enjoyable.
What the Second Hole Does
Every pipe has a bowl where you pack your material and a mouthpiece where you inhale. The second hole, usually found on the left side of the bowl, serves as an air valve. When you seal it with your finger, all the air you inhale gets pulled through the bowl, feeding the flame and drawing smoke into the chamber. When you lift your finger off, fresh air rushes in through that opening instead, pushing the accumulated smoke into your lungs in one clean burst.
This works through a simple pressure difference. With the carb sealed, you create a vacuum that pulls air only through the burning material, producing thick, concentrated smoke. The moment you release the carb, the pressure equalizes instantly. Cool outside air floods in and flushes the chamber clear. This rush of fresh air also cools the smoke by diluting it, which makes the hit noticeably less harsh on your throat.
How to Hold the Pipe
Grip the pipe so your thumb or index finger naturally rests over the carb hole. Most pipes place the carb on the left side of the bowl, which means holding the pipe in your left hand lets your thumb sit right on top of it. If the carb is on the front (as with steamroller-style pipes), you’ll use the palm of your hand or your fingertip to cover the larger opening. The key is comfort: you need to be able to seal and release the hole smoothly without fumbling or repositioning your hand mid-draw.
Keep your fingers away from the top of the bowl where the flame is. A natural grip where the pipe rests in your palm with your thumb on the carb and the bowl angled slightly away from your hand will prevent burns.
The Basic Technique
The process has two phases: filling the chamber, then clearing it.
- Cover the carb completely with your finger or thumb before you start.
- Light the bowl and begin inhaling slowly through the mouthpiece. Because the carb is sealed, all airflow passes through the burning material, pulling smoke into the pipe’s interior.
- Release the carb once you see or feel the chamber fill with smoke. Lift your finger off the hole while continuing to inhale. Fresh air rushes in and pushes the smoke straight to you.
- Exhale and repeat as desired.
The inhale should be slow and steady, not a sharp gasp. Drawing too hard can pull burning material into the pipe or make the hit uncomfortably hot.
Timing the Release for Different Hits
When you release the carb changes the entire experience. A quick release, lifting your finger almost as soon as you start inhaling, lets in fresh air early. This gives you a cooler, lighter hit with less intensity. A delayed release, where you keep the carb sealed for a longer draw, builds up denser smoke in the chamber before clearing it all at once. The result is more potent but also harsher.
Most experienced smokers land somewhere in between and adjust based on preference. You’ll develop a feel for it quickly.
Feathering for Smooth Hits
Instead of a binary cover-or-release, you can “feather” the carb by partially lifting your finger. This lets a small amount of air mix with the smoke as you draw, thinning it out in real time. Cover the carb, light the bowl, then slowly roll your finger off the hole just enough to let a thin stream of air through. You control the smoke density moment to moment, making each hit exactly as thick or light as you want.
Staggered Hits for a Slower Session
If a full hit feels like too much, try the staggered approach. Cover the carb, light the bowl, and take a gentle partial draw. Then slightly lift your finger to sip a small amount of the smoke with some air. Re-cover the carb and repeat, taking several small puffs rather than one large clearing hit. This stretches the bowl out and keeps each individual inhale mild.
Where the Carb Is Placed Matters
Side carbs are the most common design, sitting on the left or right wall of the bowl. They offer a balanced mix of airflow and smoke density and are the easiest to use. Front carbs, found on steamroller pipes, provide the most airflow and produce the strongest, most forceful hits. Back carbs tend to create denser smoke but can feel harsher because less cooling air enters the mix. The technique is identical regardless of placement; only your finger positioning changes.
Keeping the Carb Clean
Resin builds up around the carb hole over time, and if it narrows or blocks the opening, you lose the airflow control that makes the carb useful. A partially clogged carb means sluggish clearing, stale smoke, and an unpleasant taste.
For routine cleaning, a thin needle, toothpick, or straightened paperclip works well to clear resin from the hole itself. For a deeper clean, soak the pipe in isopropyl alcohol (90% or higher) and coarse salt, shaking gently so the salt acts as an abrasive inside the chamber. After soaking for 30 minutes to an hour, rinse thoroughly with warm water. Pay extra attention to the carb opening, pushing a pipe cleaner or thin tool through it to ensure the passage is completely clear. A blocked carb turns your two-hole pipe into a one-hole pipe, and you’ll immediately notice the difference in how harsh and hard to clear each hit becomes.
Troubleshooting Poor Airflow
If your pipe feels hard to draw through even with the carb open, the problem is usually a blockage somewhere in the airpath. Check the carb hole first for visible resin buildup. Then inspect the channel between the bowl and the mouthpiece, which is the most common spot for clogs. A pipe cleaner pushed through the mouthpiece should pass through with minimal resistance if the path is clear.
Some pipes simply have a tighter draw by design, especially handmade glass pieces where hole sizes vary. If the carb hole seems too small to provide a satisfying clearing rush, you can compensate by drawing more slowly during the fill phase (giving smoke more time to accumulate) and inhaling more sharply when you release the carb. This maximizes the pressure difference and helps clear the chamber despite the smaller opening.