Sealing ring made of natural rubber: Nothing drips
Part four of our soulessentials series is dedicated to a small but truly powerful part of our soulbottles: the natural rubber sealing ring. Nice and soft, colorful, extra-tight – but what exactly is natural rubber and how is it processed?
Elastic, as a band, as a ring, or to chew: The word "rubber" probably brings to mind a lot of different things. But what's in our natural rubber sealing ring—and why isn't all rubber created equal?
What is natural rubber?
Rubber is a rubber-like substance found in latex—latex, in turn, is just another name for the milky sap of the rubber tree. Latex can also be obtained from other plants, but the majority comes from the tree in question, also known as Hevea Brasiliensis. Today, this tree grows primarily in Asia, including Indonesia and Sri Lanka. The rubber tree originated in the Amazon rainforest. A cut is made all around the bark of the tree, just deep enough for the sap to drip out and be collected.
But before this raw material can be used for everyday products – like our natural rubber sealing ring – it must be further processed. There are various different variants: Liquid, so-called centrifuged rubber is the basis for such wonderful products as condoms. To create a solid mass, from which rubber boots or our soulbottles sealing ring are made, a process called vulcanization is used . In this process, the natural rubber is treated with heat (maximum 160 degrees Celsius) and, traditionally, with sulfur. This ensures that the mass no longer sticks and at the same time remains elastic. The more sulfur, the harder the end result. Vulcanization is essentially what transforms natural rubber into the rubber we know.
And this is being done on a very large scale: According to the Federal Environment Agency, there are a total of 40,000 products worldwide that use natural rubber. By far the largest consumer is the tire and automotive industry. Also according to figures from the Federal Environment Agency, they account for around 85 percent of imported natural rubber on the European market.
Is natural rubber really sustainable?
Our small sealing rings made of natural rubber obviously can't compete with the quantities of car tires produced with this material. And that's a good thing! The huge demand is not without its problems for a natural product that once grew hidden in the Amazon rainforest. To put it briefly: The product of the rubber tree was already being used by humans in the 17th century. With the development of vulcanization in the mid-19th century, a veritable rubber boom followed. To meet demand, vast rubber plantations were established, which are now found primarily in Asia. The fact that cultivation, harvesting, and processing sometimes took place under completely unsustainable conditions has led, among other things, to the founding of initiatives like Fair Rubber .
Since 2018, we have been sourcing Fair Rubber-certified natural rubber as raw material from Sri Lanka. In Germany, the rubber is further processed into our sealing rings. In addition to three percent natural sulfur (which is as little as possible), oxides and natural chalk are added. This special blend of additives is necessary to achieve the desired rubber consistency. However, we can assure you that the mixture developed specifically for us has been rigorously tested to rule out any health-related findings. What we consciously avoid in our rubber rings are petrochemical-based chemicals and plasticizers. You can read about the contents of the latter here – which, for us, are enough reasons to avoid plasticizers.
Sealing ring made of natural rubber for soulbottles: That's why
One reason why natural rubber has won our hearts: It's plastic-free. And thus corresponds to our goal of avoiding plastic in everyday life whenever possible. The majority of other bottle caps are sealed with silicone, which belongs to the group of synthetic polymers. This doesn't mean that we can simply consume valuable raw materials like natural rubber carelessly and without regard for losses just because we want to avoid synthetics. This made the aforementioned Fair Rubber certification all the more important to us, as it not only strictly regulates consumption but also makes it more transparent. Another advantage of natural rubber: The rubber tree stores large amounts of CO₂ , thus reducing the amount of greenhouse gas in the atmosphere. The natural rubber sealing ring is robust and can therefore be used again and again. It only needs to be cleaned regularly, just like your soulbottle. Cleaning tips can be found here.
And now we've almost forgotten the crucial feature of our stylish drinking bottles : The thing is leak-proof. The rubber ring fits between the ceramic lid and the bottle neck. Once closed, the rubber-ceramic team keeps your drink drip-proof in the bottle. Incidentally, it also keeps tea, juice, or whatever you like.
The advantages at a glance
- 100% plastic-free
- drip-proof
- Fair Rubber certified
- without petrochemical-based chemicals
- without plasticizers
By the way: All of our drinking bottles have natural rubber sealing rings, including our three new stainless steel drinking bottle versions : soulbottle steel. And if you ever need to replace your sealing ring or want a different color, no problem: You can also purchase them individually. Just stop by our shop .
