With so many different options on the market today, you might find yourself wondering, is it even safe to smoke out of metal? The truth is, it depends on what metals you’re choosing, how these metals are processed, and whether or not the company has a proper chain of custody. We’re going to have to use a little science and engineering to understand how metals react to heat, but we’ll try and keep it simple, the full equations are much more complicated.
Let us consider the three most common types of metals used when smoking flower: brass, aluminum, and stainless steel. To evaluate if a metal will release air-borne atoms when exposed to heat we need to take into account three parameters: the melting point (both for liquid and gas phase), the Specific Heat Capacity (how much energy needs to be put into an object to raise its temperature), and the mass/shape of the object. To help explain how these parameters interact, we will use our old friend water as a base line, more specifically an ice cube from your freezer. Water turns to liquid at 0˚C and turns to gas at 100˚C and it has a specific heat capacitance of 1 Btu. If you were to flick your lighter and hold it up to the ice cube, over time the ice would melt into water and then if you were to hold the lit lighter over the pool of water eventually the water would heat up, turn into a gas, and escape into the room. As you can imagine, this process could take hours to fully vaporize all of the water of the ice cube, due to the specific heat capacity of water and the mass/shape of the ice cube. Now consider that instead of an ice cube from your freezer we look at a snowflake the size of a quarter and as thin as a piece of paper, it has much less mass than the ice cube and the mass is very spread out. If you flick your lighter under the center of the snowflake you will see it very quickly evaporate, the lighter is hot enough to take the water from the solid phase, right through the liquid phase and into the gas phase.
Circling back, let’s consider the three types of metals in two forms: thick like an ice cube or 14mm bong bowl, and thin like a snowflake or screen. In the case of a thick object, all three metals will stand up to a lighter’s max temperature of 1970 ̊C. The specific heat capacity as well as other thermal transfer properties ensure that heat introduced can be passed through and radiate away from the metal before the melting temperature is reached. This is not true for thin objects, like a screen. Aluminum screens aren’t available, so we can eliminate them from the discussion. Brass has a melting point of 900˚C and stainless steel has a melting point of 1500 ̊C. While at first it would seem that both screens would burn with a lighter, more detailed thermal analysis reveals that the lower specific heat capacity and higher thermal conductivity of brass allow the screen to heat up rapidly and reach melting temperatures quite quickly. Stainless steel’s 600 degree advantage over brass and more stable thermal properties make them impervious to a lighter’s flame, even a mini torch can’t damage this metal!
Now let’s switch gears to something called chain of custody. This tracks the product from manufacturing, to shipping, to assembly, and on to shelves for sale. Safeguarding the process is just as important as what materials you choose to use. Purchasing cheap knock-offs puts the consumer at risk of poor quality materials. For example, many types of brass contain up to 8% lead (which melts at 327˚C), leaving the consumer to guess if they are getting lead-free brass or not. We at Invincibowl keep a close eye on our manufacturing and know definitively that our products are made of hard anodized 6061 aluminum and 304 stainless steel.
We go above and beyond to ensure that our customers are consuming their cannabis in the safest way possible. In addition to choosing the most durable and chemically inert materials, we have created a proprietary secure-screen system. This system permits your flower to be in contact with only 304 surgical stainless steel. The insert and the screen are what make up the structure of this system. The insert holds the screen in place allowing the user to easily flip over the bong bowl to discard ash.
Both stainless steel and anodized aluminum are corrosion and oxidation-resistant. This makes them easy to sanitize and promotes sustainability and re-use. Brass on the other hand can oxidize when in contact with water which causes it to tarnish to a black-green color.
In summary, we would not recommend brass in any configuration. Screens will definitely melt with continuous lighter exposure, while thicker pipes may have 2-8% lead content which could leech from the brass, putting you at risk. There is no configuration where stainless steel is subject to erosion by a lighter’s flame and is safe to use for both screens and pipes. Aluminum is protected from melting and erosion when in bulkier forms, and a hard anodized coating ensures that the entire object maintains cohesion.