Natural resins are useful, diverse, and valuable to any material collector. Particular trees (such as fir, pine, spruce, and frankincense) yield sweet sap that can heal skin ailments, amongst other things. For millennia, many civilizations across the world have used tree resins therapeutically, burning them as incense for spiritual guidance, cleansing and piety - amongst other things. To this day world religions still make use of resin to help facilitate prayer and deepen sensory experiences within holy places. Resin from conifer trees smell citrusy and fresh whereas the aroma of frankincense is sugary and clings heavy by comparison. Frankincense also contains compounds which actively calm the nervous system when inhaled.
Survivalists may use tree resin to start and maintain fires (through fatwood), and speed up the process of wound healing, by melting and mixing it into a multipurpose salve. It is easy to collect by finding resinous trees, most of which have sap naturally coagulated on the bark - especially around places where the trees have sustained damage, in the manner of a scab. It is easy to harvest resin sustainably and even without hurting the tree, as long as you don't remove too much, resulting in the tree leaking further. However, harvesting frankincense is a dying profession which involves deliberately making incisions along the tree bark from which gum can leak and harden, but the overall process takes time and respect, built up over years.
Resin is also an amazing waterproof material that can also be used for glue which is how I intend to - at least for beyond its medicinal and cultural purposes – which I admit I value it for the most. It can serve as an excellent sealant that renders surfaces waterproof, but it's tough to melt and messy to use without designating equipment exclusively to the craft. That being said a smooth, thick layer will harden adequately without cracking, and fully dried resin will lose its stickiness, unless manipulated out of that state again. Resin can be melted and hardened continuously, with little to no risk of undesirable changes such as brittleness.
Gum arabica is also an ingestible resin commonly used in food, cosmetics, and adhesives. Rosins made from various tree saps are also used to enhance friction and improve the grip between surfaces that lack these qualities. All resins can be used as thickening agents.
Depending on your desired use, tree resin is certainly a valuable material to keep, as it offers diverse solutions to one’s material experiments, both in and out of the atelier. Here’s to gradually collecting and sampling from all over the world!