Reclaimed rubber is salvaged rubber from old tires, inner tubes, gaskets and hoses that has been ground, softened by heat and re-milled so it can be compounded and cured again. It is weaker than virgin rubber, at 50-70% of the original strength, but it is the largest immediate source of rubber after a collapse and is good enough for floor mats, vibration mounts and low-pressure gaskets. It does not need a plantation, only salvage and a mill.
Part of Rubber Processing
Turning scrap vulcanised rubber back into a workable compound, and what it can and cannot do.
Salvage Is The Largest Rubber Supply Before The First Tree Is Tapped
The carrier lists salvage as the largest immediate source, ahead of every plant. A village with a scrapyard of tires, tubes and hoses has rubber now, while a rubber tree takes years to mature and tapped latex yields only 2-5 kg of dry rubber per tree per year (see Natural Latex Collection).
The catch is that scrap rubber is already vulcanised. Its chains are tied together with sulfur bridges and it can no longer be softened and re-shaped. Reclaiming breaks enough of them to make it workable again, at a cost in strength.
| Step | What it does | Article |
|---|---|---|
| Sort and grind | Separates rubber from fabric and metal, makes crumb | here |
| Devulcanise | Breaks cross-links with heat and a reclaiming agent | Devulcanization Methods |
| Blend | Mixes reclaim with fresh rubber | Blending with Fresh Rubber |
What You Need
- Scrap rubber: old tires, inner tubes, gaskets, hoses.
- A knife and saw to cut tires apart and remove steel or fabric.
- A toothed mill to grind crumb; see Devulcanization Methods.
- A heat source and reclaiming agent such as pine tar or rosin oil, per the carrier.
- A two-roll mill for the last step; see Compound Mixing.
Method: What To Salvage First
Step 1: Sort by type. Inner tubes and hoses give cleaner rubber than tire casings, which carry fabric and wire.
Step 2: Strip contaminants. Remove metal, fabric and dirt.
Step 3: Grind to crumb of 1-2 mm per the carrier.
Step 4: Devulcanise and mill, then compound.
Step 5: Use it where strength is not critical: the carrier lists floor mats, vibration mounts and low-pressure gaskets.
Common Mistakes
- Using reclaim for critical seals. At 50-70% of virgin strength it is not the right rubber for a high-pressure seal.
- Leaving wire or fabric in. It tears the mill and weakens the product.
- Burning scrap to dispose of it. See the danger block.
Safety
Never burn scrap rubber
Burning rubber gives off dense toxic smoke containing sulfur compounds and soot and is very hard to put out (recalled general fact, not from the corpus). Grinding scrap also makes fine rubber dust. Reclaim by heat in a controlled bath or oven, not an open fire, work in moving air outdoors, and keep a bucket of sand to smother a pot fire.
What’s Next
- Learn next: Devulcanization Methods — softening the crumb
- Combine with: Blending with Fresh Rubber — stretching a scarce supply