In a tubular lead-acid battery, the positive plate is not a flat grid — it is a row of woven polyester tubes packed with active material. Those tubes, the gauntlet, are the only thing holding the active mass against the spine through years of charge and discharge. If the gauntlet softens, swells, or loses its shape, active material sheds to the bottom of the cell and the battery loses capacity. The binder that stiffens that fabric is doing more work than its cost suggests.
Why a Gauntlet Binder Is Needed at All
Woven PET on its own is flexible. Inside a cell it has to stay dimensionally rigid while sitting in sulphuric acid, at temperature, under the mechanical stress of active material expanding and contracting on every cycle. The binder impregnates the weave and cures into a stiff film that locks the tube’s geometry — while leaving the fabric porous enough for electrolyte to move freely. Stiffness and porosity pull in opposite directions, and that trade-off is the whole design problem.
What the Binder Has to Survive
Three service conditions decide whether a gauntlet binder holds up: the acid, the heat of curing, and long-term oxidation inside the cell. A binder that passes on stiffness but fails on oxidation resistance will embrittle and powder over time.
| Property | GT-1000 |
| Chemistry | Self-crosslinking acrylic copolymer |
| Solids content | 45 ± 1% (105°C, 3 hrs) |
| pH | 6 – 7 at 30°C |
| Viscosity (Brookfield) | 80 – 120 cps, RVT #2 / 20 / 30°C |
| Viscosity (flow cup) | 14 – 18 seconds, B4 Ford Cup at 30°C |
| Cured film | Slightly hazy and brittle, 100 micron film |
| Thermal stability | Up to 215°C curing temperature |
Note the film description: slightly hazy and brittle is the specification, not a defect. A gauntlet binder is one of the few acrylic applications where a soft, clear, flexible film would be the wrong result.
Impregnation and Curing: Step by Step
- Impregnation — dip 100% PET woven tubular gauntlet fabric into the emulsion, adjusting weight pick-up to 25–30% via padding rolls to reach target stiffness
- Drying — dry the impregnated fabric at 70°C for 30 minutes
- Cutting and rodding — cut to required dimensions and insert stainless steel rods into the gauntlet tubes
- Curing — cure at 200–215°C for 10 minutes to activate crosslinking
- Finishing — de-rod and pack
Weight pick-up is the variable worth controlling tightly. Too little and the tube stays limp; too much and you close off the porosity the cell needs.
Focus Polymers GT-1000
GT-1000 is our self-crosslinked acrylic copolymer emulsion for PET tubular gauntlet fabric. It requires no external crosslinker, resists sulphuric acid and oxidation inside the cell, and is stable to 215°C curing. It is supplied in 55 kg and 220 kg packs with a four-month shelf life, stored between 5°C and 35°C and protected from freezing, and is manufactured at our ISO 9001:2015 certified plant in Roorkee.
Full specifications and the technical data sheet are on the GT-1000 product page. For trial quantities, contact our technical team.