Ark Composites
2:1 Epoxy Resin
2:1 Epoxy Resin
SKU:AR8
Ark Composites 2:1 Epoxy Resin (Part A) is our water-clear, low-viscosity, no-blush epoxy, formulated for boat building and repair. Combined with ARK Fast, Medium or Slow Hardener at 2 parts resin to 1 part hardener, it coats, laminates, bonds, fills and fairs wood, fiberglass, plastic, metal and concrete.
Choose the hardener for your working time and shop temperature, using the cure-time tables below.
At a glance
- Mix ratio: 2:1 by volume (100:50); 100:43 by weight
- Hardeners: ARK Fast, ARK Medium or ARK Slow
- Finish: water clear, no blush. No blush wash is needed between coats unless you are working in freezing rain.
- Recoat window: 2–6 hours while the previous coat is still tacky
- Casting depth: up to 1 in (25 mm) per pour with ARK Slow Hardener
- Pigment: up to 5% ARK Pigment; also accepts metal flake, fabric, powders and virtually any dry additive
- Thickeners: ARKTHIX, colloidal silica, cotton fibre, wood flour or microballoons for glue, gap filler and fairing compound
- Sizes: 8 oz (237 mL), 16 oz (473 mL), 1 quart (946 mL), 1/2 gallon (1.9 L), 1 gallon (3.78 L) and 4 gallons (15.14 L)
What it's for
- Waterproof coating for wood, metal and most porous surfaces
- Fiberglassing canoes and small boats; laminating fiberglass, carbon and Kevlar
- Gluing, thickened with ARKTHIX, colloidal silica or cotton fibre to prevent run-out and fill gaps
- Sandable fairing compound and structural gap filler
- Clear casting and pigmented pours
- Fiberglass, metal and plastic repairs on boats, ATVs, PWCs and polyethylene kayaks
Application
1. Prepare the surface
Surfaces must be clean, dry and free of oil, wax and paint. Wipe with acetone on a clean cotton cloth, and sand cured epoxy, fiberglass, metal and plastics. Do not use Varsol or petroleum-based solvents.
2. Measure and mix
Measure 2 parts resin to 1 part ARK Hardener in graduated containers. Too much or too little hardener will prevent a proper cure, so never estimate. Mix thoroughly, scraping the sides and bottom of the container, then add fillers if needed. Mix only what you can use within the pot life; pouring the batch into a paint tray or other flat container extends working time.
3. Apply and recoat
Spread with a solvent-resistant brush, roller or squeegee. Apply the next coat as soon as the previous one is tacky, between 2 and 6 hours depending on hardener and temperature. After 8 hours, or once the epoxy has cured hard, sand with 80-grit paper before applying more epoxy or any other coating.
4. Finish
Allow full cure (2–7 days at 22 °C / 71 °F, all hardeners) before painting or varnishing. Two-part polyurethane paint performs best over epoxy. Cured epoxy will chalk in sunlight unless protected by varnish or paint.
Hardener selection and cure times
At 22 °C / 71 °F
| Hardener | Pot life | Gel time | Sandable | Full cure |
|---|---|---|---|---|
| Fast | 8–10 min | 15–20 min | 6–8 hrs | 2–7 days |
| Medium | 10–15 min | 20–40 min | 8–12 hrs | 2–7 days |
| Slow | 15–20 min | 30–60 min | 15–24 hrs | 2–7 days |
At 12 °C / 54 °F
| Hardener | Pot life | Sandable |
|---|---|---|
| Fast | 15–20 min | 10–14 hrs |
| Medium | 20–30 min | 12–20 hrs |
| Slow | 35–40 min | 24–48 hrs |
Pot life, gel and sanding times vary with temperature, mixed volume, time in the mixing container and laminate thickness. As a rule, they roughly double for every 8 °C (about 14 °F) drop in temperature and halve for every 8 °C rise.
Technical data (with ARK Medium Hardener)
| Property | Imperial | Metric |
|---|---|---|
| Viscosity @ 25 °C | Resin (Part A): 600–950 cps; mixed: 300–700 cps | |
| Specific gravity | Resin (Part A): 1.13–1.15; mixed: 1.08–1.10 | |
| Gel time, 150 g mass in cup @ 22 °C | 15–20 min | |
| Tensile strength (ASTM D638) | 7,617 psi | 52.5 MPa |
| Tensile modulus (ASTM D638) | 163,464 psi | 1,127 MPa |
| Elongation at break (ASTM D638) | 6.6% | |
| Compressive strength (ASTM D695) | 10,558 psi | 72.8 MPa |
| Compressive modulus (ASTM D695) | 232,985 psi | 1,606 MPa |
| Flexural strength (ASTM D790) | 14,339 psi | 98.9 MPa |
| Flexural modulus (ASTM D790) | 459,688 psi | 3,169 MPa |
| Hardness (ASTM D2240) | 84–85 Shore D | |
Typical lab values for ARK Epoxy Resin cured with ARK Medium Hardener; these are not specifications. Liquid properties are measured at 25 °C. Gel time is a lab test of a 150 g mass in the cup, not working time on the job. Metric values are converted from psi.
Safety and storage
ARK Epoxy Resin (Part A) is labelled WARNING: harmful if swallowed; causes skin irritation and serious eye irritation; may cause an allergic skin reaction. ARK Hardeners (Part B: Slow, Medium and Fast) are labelled DANGER: causes severe skin burns and eye damage; may be corrosive to metals; may cause allergy or asthma symptoms or breathing difficulties if inhaled; may cause an allergic skin reaction; may cause damage to organs (lungs, kidneys) through prolonged or repeated exposure. Vapours and mists are corrosive to the respiratory tract.
Wear chemical-resistant (nitrile) gloves, chemical splash goggles (no contact lenses) and long sleeves, and work in a well-ventilated area; do not breathe vapours or mists, and use an approved respirator if ventilation is inadequate. Clean epoxy off skin with soap and water, never solvents. Store at room temperature in the original, tightly closed containers, upright and off concrete floors; keep hardeners locked up and away from metals; do not freeze.
Data sheets
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