Ribbed smoked sheet rubber is made by rolling coagulated rubber into sheets 3-5 mm thick, hanging them in a smokehouse and smoking them with hardwood smoke at 50-60 °C for 5-7 days. The smoke acts as a fungicide and antioxidant and colours the rubber amber to brown. Kept dry and cool, the sheets store for years, so smoke curing is the way to hold rubber between harvests and vulcanisation runs.
Part of Rubber Processing
Drying and preserving rubber sheet in wood smoke for storage and trade.
Smoke Preserves The Sheet While It Dries
Wet coagulum goes mouldy and rots in days. Rolling it thin and holding it in warm smoke dries it and coats it with smoke compounds that resist fungus and oxidation. The corpus’s Latex Processing article says the smoke provides antimicrobial phenols; the carrier calls the smoke a fungicide and antioxidant. Both agree on the mechanism.
The two articles give different schedules.
| Item | Carrier | Latex Processing |
|---|---|---|
| Sheet thickness | 3-5 mm | not given |
| Temperature | 50-60 °C | 40-55 °C |
| Time | 5-7 days | 3-5 days |
| Storage | Years if dry and cool | Unvulcanised rubber stores 6-12 months |
The ranges overlap only at 50-55 °C. Treat that as the safe common ground and judge the end of the cure by the sheet itself: it should be uniformly amber to brown, dry and translucent when held to the light, with no wet white core.
What You Need
- Washed coagulum from Acid Coagulation.
- A hand roller or mangle to make 3-5 mm sheets. Ribbed rollers put the characteristic ribs on the sheet (recalled, not from the corpus).
- A smokehouse with a low fire, hanging rails and a way to measure or judge temperature; see Latex Collection and Preservation for the timing before the sheet.
- Hardwood for the smoke; avoid resinous softwood.
- Talc, chalk or fine clay to stop sheets sticking in storage.
Method: Smoking A Sheet
Step 1: Roll the coagulum into sheets 3-5 mm thick.
Step 2: Drain briefly, then hang the sheets in the smokehouse without touching.
Step 3: Smoke at 50-60 °C with hardwood smoke, keeping the fire low and steady.
Step 4: Check daily. Turn or move sheets that sit near the hot side.
Step 5: Finish when dry and amber. The carrier says 5-7 days.
Step 6: Dust with talc and store dry and cool.
Worked Example
Smokehouse load: a sheet 3-5 mm thick and, say, 50 × 30 cm (an assumed size) has a volume of 50 × 30 × 0.4 = 600 cm³ at 4 mm, which at roughly 1 g/cm³ (an assumption, rubber is a little lighter than water) is about 600 g wet. If the latex-processing article’s 40-60% water content applies, the dry rubber is 240-360 g per sheet, so 100 kg of dry rubber needs about 100,000 ÷ 360 ≈ 280 to 100,000 ÷ 240 ≈ 420 sheets hanging at once or in rounds.
Common Mistakes
- Smoking too hot. Rubber melts in heat and the carrier says it degrades.
- Resinous wood. Tarry smoke leaves a sticky, dark surface.
- Sheets touching. They stick and dry unevenly.
Safety
Smokehouse fire and carbon monoxide
A smokehouse is a fire in a closed building. Keep the fire in a metal or brick firebox away from hanging sheets, which are combustible rubber, keep a bucket of water or sand beside it, and never sleep in or enter a smoke-filled house without ventilating it first, because smoke carries carbon monoxide (recalled general fact, not from the corpus).
What’s Next
- Learn next: Sulfur Vulcanization — turning sheet into durable rubber
- Combine with: Crepe Rubber Production — the alternative to smoke