What Is Epoxy Resin?
Epoxy resin is a two-component plastic consisting of resin (Component A) and hardener (Component B). Only when both components are mixed does a chemical reaction (polymerization) start, transforming the liquid mixture into a solid, crystal-clear and extremely durable plastic.
Unlike other resins (polyester, polyurethane), epoxy shrinks only minimally during curing (approx. 1-2%). It adheres excellently to most materials, is chemically resistant and achieves high mechanical strength.
Common Mixing Ratios
2:1 by volume: The standard ratio for most all-purpose epoxy resins. Two parts resin to one part hardener. Easy to measure, good processing properties, medium pot life of approximately 25 minutes.
3:1 by volume: For slow-curing systems used with large casting volumes (river tables, jewelry). The longer pot life of 45+ minutes allows working with larger volumes without premature gelling.
5:1 by volume: For thin coatings and sealants. The high resin proportion yields a very thin-liquid mixture with excellent flow properties. Ideal for garage floors and countertop sealing.
100:45 by weight: The European industrial standard. Mixed by weight, which is more accurate than volume. 100 grams resin to 45 grams hardener. This ratio is found in most professional systems.
The Most Common Mixing Mistakes
Mistake 1: Wrong ratio. Even small deviations (10-15%) lead to poor curing. The result is a sticky, soft surface that never properly hardens. Solution: Always use a scale, never estimate by eye.
Mistake 2: Insufficient mixing. If resin and hardener are not completely blended, soft sticky spots remain. Solution: Stir for at least 3 minutes, scraping sides and bottom of the container. Then pour into a clean container and stir for another minute.
Mistake 3: Mixing too much at once. The reaction is exothermic (heat-releasing). Large quantities in a tall container can heat above 100 degrees, causing immediate gelling, discoloration and in extreme cases smoke. Solution: Mix maximum 500ml at once and pour flat immediately.
Mistake 4: Wrong temperature. Below 15 degrees Celsius, epoxy becomes viscous and difficult to process. Curing slows drastically. Above 30 degrees, pot life shortens considerably. Optimal processing temperature: 20-25 degrees Celsius.
Understanding and Using Pot Life
Pot life (also working time or open time) is the timespan between mixing and the point where the mixture becomes too thick to process. It depends on resin quantity, temperature and hardener type.
Typical pot lives: Floor coatings 20-25 minutes, laminating resins 25-30 minutes, casting resins 40-60 minutes. For every degree above 25 Celsius, pot life shortens by approximately 5%.
Pro tip: Pour the mixture flat immediately after stirring. In a bucket, heat concentrates and pot life halves. Spread on a flat surface, the resin remains workable longer.
Applications and Layer Thicknesses
Garage floor coating: 2-3mm thickness, consumption approx. 3-4.5 kg/sqm. Two coats recommended (primer + topcoat). Curing: 24h walkable, 7 days fully loadable.
River table / casting resin: 20-50mm thickness. Pour maximum 20mm per layer, otherwise the mass overheats. Wait 24 hours between layers. Consumption: 1.1 kg per liter of volume.
Crack filling: Epoxy is injected into cracks with a cartridge gun. Consumption depends on crack width and depth, typically 0.5-2 kg per linear meter.
Sealing: 0.3-0.5mm thickness, consumption approx. 0.15-0.25 kg/sqm. One coat suffices for dust protection, two coats for mechanical loading.