Water pipes & bongs
by Black Leaf
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A conical glass bowl is a tapered, funnel-shaped slide that slots into your bong or water pipe's joint and holds your milled herb in place while you smoke. Available in 14mm and 18mm joint sizes, this one is made from borosilicate glass — the same heat-resistant material used in lab equipment and decent cookware. It's cheap, it fits standard glassware, and it means you're never stuck with a cracked bowl and nothing to smoke from on a Friday evening.
Check the joint on your bong or water pipe before ordering. The measurement refers to the diameter of the ground glass joint where the bowl sits — not the bowl opening at the top. The 14mm (also called 14.5mm) is the most common size on medium bongs and bubblers. The 18mm (18.8mm) tends to show up on larger pieces with wider downstems. If you're not sure, measure the inner diameter of the female joint on your piece, or drop the shop a message. Ordering the wrong size is the number one reason people end up buying two.
| Variant | Joint Size | SKU | Best For |
|---|---|---|---|
| 14 mm | 14.5mm ground glass | HS1407 | Medium bongs, bubblers, most standard pieces |
| 18 mm | 18.8mm ground glass | HS1408 | Larger bongs, beaker bases, heavy-duty rigs |
| Spec | Detail |
|---|---|
| Material | Borosilicate glass |
| Available sizes | 14mm and 18mm |
| Shape | Conical (tapered funnel) |
| Joint type | Male — fits into female joints on bongs and water pipes |
| Compatibility | Universal fit for all standard ground glass joints of matching size |
| Heat resistance | Borosilicate withstands rapid temperature changes up to approximately 165°C differential |
| Colour | Clear |
Complete your setup: if your downstem is looking tired too, grab a replacement glass downstem in the matching joint size. A set of pipe screens keeps ash out of your water and makes cleaning less of a chore. And a decent herb grinder — even a basic aluminium one — makes a real difference to airflow through a conical bowl like this.
Here's what we've seen behind the counter for over 25 years: the bowl is always the first thing to go. It's the part you handle most, the part that gets the hottest, and the part most likely to roll off the table when you set it down. A cracked or chipped bowl doesn't just look rough — it can create an uneven seal against the joint, which means air leaks, poor suction, and wasted herb. Not the end of the world, but annoying enough to ruin a session.
Borosilicate glass handles heat far better than regular soda-lime glass. According to research on antibacterial borosilicate glass compositions, borosilicate formulations demonstrate strong chemical durability and resistance to thermal shock (PMC10233686). In practical terms, that means you can torch this bowl repeatedly without it cracking from temperature swings — something cheap glass bowls from market stalls absolutely cannot promise. We've had customers bring back no-name bowls that split after a week. Borosilicate doesn't do that.
The conical shape matters too. Compared to a flat-bottomed or cylindrical bowl, a cone concentrates your herb towards the centre, which gives you more even airflow and a cleaner burn right down to the bottom. Less waste, less relighting, less poking around with a tool trying to get the last bits to catch. The one honest limitation: because it's a simple cone without a built-in screen or pinch, finely ground herb can pull through if you don't use a small glass or metal screen. Toss one in — problem solved.
When someone walks into the shop with a broken bowl, the first thing we ask is: "14 or 18?" About 60% of the time, they don't know. So we hand them both sizes and let them test the fit on a display piece. If you're ordering online, measure first. A 14mm bowl in an 18mm joint just drops straight through — it's not a "close enough" situation. The tolerances on ground glass joints are tight, usually within 0.5mm.
The second thing we tell people: buy two. One to use, one in the drawer. A conical bowl weighs almost nothing, costs very little, and saves you from that specific frustration of having a fully loaded bong and nothing to smoke from. We've been selling these since the early days of the shop, and the customers who come back annoyed are always the ones who didn't grab a backup.
A conical glass bowl is the removable slide that sits in your bong's downstem joint. You pack it with ground herb, light it, and the smoke travels through the downstem into the water. The conical shape funnels herb towards the centre for even airflow. It's the most common bowl shape for standard water pipes.
Measure the inner diameter of the female joint on your bong or downstem. 14mm joints are roughly the width of a pencil; 18mm joints are noticeably wider, closer to the diameter of a 1-cent coin. When in doubt, measure with a ruler or callipers. The two sizes are not interchangeable.
It fits any bong or water pipe with a standard ground glass female joint in the matching size (14mm or 18mm). That covers the vast majority of glass bongs on the market. It won't fit silicone bongs with rubber grommet connections or non-standard proprietary joints.
Strongly recommended. A conical bowl has an open hole at the base, so finely ground herb can pull through into the water. A small glass daisy screen or metal gauze screen stops this. They cost almost nothing and save you from drinking bong water — always a good trade.
Soak in 90%+ isopropyl alcohol with a tablespoon of coarse salt for 10–15 minutes. Shake gently, then rinse with warm water. For stubborn resin near the narrow base, use a pipe cleaner or cotton bud. Clean after every few sessions to maintain airflow and flavour.
Yes. Borosilicate glass handles thermal shock — the rapid heating and cooling cycle of lighting a bowl — far better than standard soda-lime glass. It's the same type of glass used in laboratory beakers and high-end cookware. It won't crack from normal use the way cheap glass does.
A standard conical bowl holds roughly 0.15–0.3g of ground herb, depending on how tightly you pack it. For the best draw, pack loosely — air needs to pass through the herb evenly. Overpacking restricts airflow and makes you work harder for less smoke.
Last updated: April 2026
