The curing time of deep-poured epoxy resin is not entirely consistent. It mainly depends on three key factors: product formulation, pouring thickness and environmental conditions. The entire curing process can be divided into three stages: gelation/surface drying, initial curing and full curing, with significant differences in the time range of each stage.
The following are reference standards based on general industry norms and Jinhua Resin products (for reference only):
1、Core solidification stage and reference time
The curing of deep-poured epoxy resin is a chemical reaction process between epoxy resin and curing agent, which involves an irreversible transformation from a liquid state to a transparent solid state.
The time reference for each stage is as follows:
（1）Gelation/Surface Drying Stage (touchable without stickiness)
During this stage, the epoxy resin gradually thickens from a liquid state, loses its fluidity, and becomes dry and non-sticky to the touch (i.e., the “tacky cure” state). This typically occurs around 24 hours after mixing, but may extend to 48 hours for some slow-drying products; if the ambient temperature is high (e.g., close to 75°F/24°C), it can be shortened to 18-24 hours. The key function of this stage is to provide an operational window for subsequent multi-layer casting. If multiple coatings are required, it is recommended to complete them at this stage (to avoid the need for additional sanding to increase adhesion after complete curing).
（2）Initial Curing Stage (transportable/for simple processing)
At this point, the epoxy resin has fully hardened and can be handled, sanded, and trimmed, but it has not yet reached its maximum strength. The initial curing time for most mainstream deep-cast epoxy resins is 24-72 hours: fast-curing products reach this state in 24-36 hours (under a standard environment of 70°F/21°C), while conventional products require 48-72 hours. For products used in river tables or large-scale craft casting, it is generally recommended to perform subsequent processing after initial curing to avoid deformation caused by stress before hardening.
（3）Full curing stage
Once epoxy resin has fully cured, it will form a hard, glassy texture, possessing all the properties of water resistance, abrasion resistance, and impact resistance. Only then is it suitable for formal use. This stage takes a relatively long time, typically 5-7 days. For some high-quality products or thick-layer casting scenarios (such as single casting thickness exceeding 1 inch), complete curing may take 1-2 weeks until peak strength is reached.
2、Key factors affecting curing time
深The curing time of epoxy resin is affected by a variety of factors. In actual operation, the following points should be paid special attention to avoid incomplete curing (stickiness, softening) or performance degradation due to unsuitable conditions:
（1）Pouring thickness (the most critical influencing factor)
“Deep casting” of epoxy resin is defined as a single pour thickness ≥ 0.5 inches (1.27 cm). The greater the thickness, the longer the curing time:
• Single pour thickness 0.5-1 inch: Initial curing 24-48 hours, complete curing 5-7 days;
• Single pour thickness exceeding 1 inch: Requires multiple pours (each layer spaced 24-48 hours apart), extending the overall complete curing time to 7-14 days; If a single, thick pour (e.g., exceeding 2 inches) is attempted, it may cause yellowing, cracking, or even failure to cure due to the inability to dissipate internal heat.
（2）Ambient Temperature and Humidity
Epoxy resin curing relies on a chemical reaction, and temperature directly affects the reaction rate:
• Ideal temperature: 60-75°F (15-24°C). Within this range, curing time meets product specifications.
• Temperatures below 60°F (15°C): The reaction slows down, curing time is extended by 30%-50%, and the surface may become sticky while the interior softens.
• Temperatures above 75°F (24°C): The reaction accelerates, curing time is shortened, but excessive heat release may cause yellowing and deformation of the product.
• Humidity: Must be controlled below 85%. High humidity interferes with the curing reaction, causing surface fogging, reduced gloss, and even affecting adhesion.
（3） Product Formulation and Mixing Ratio
There are significant differences in the formulations of deep-poured epoxy resins from different brands, and their curing times also vary accordingly:
- Rapid-curing type: Initial curing takes 24–36 hours, suitable for projects with tight schedules.
- Standard slow-curing type: Initial curing takes 48–72 hours (e.g., Jinhua Resin products). It features lower exothermicity, making it ideal for thick-layer pouring and reducing the risk of cracking.
- Mixing ratio: Most deep-poured epoxy resins follow a ratio of 2:1 or 3:1 (resin to curing agent, by volume). A ratio deviation exceeding 5% will severely impair the curing process, resulting in permanent tackiness or incomplete curing. It is essential to mix the components precisely in accordance with the product instructions and stir thoroughly (for at least 3–5 minutes), ensuring no residue adheres to the container walls or bottom.
3、Practical Operation Recommendations
Prioritize Following the Product Instructions: Curing times may vary across different brands. Prior to official construction, it is imperative to check the labeled “gel time”, “initial curing time” and “full curing time” on the product packaging, as these serve as the most accurate reference criteria.
Interval Between Multiple Pouring Layers: If the total thickness of the project exceeds 1 inch, it is recommended to pour in multiple layers with each layer controlled to a thickness of 0.5–1 inch. The interval between adjacent layers should be 24–48 hours (subject to the first layer being fully surface-dried and non-sticky to the touch).
Environmental Control: Maintain a clean, dry and well-ventilated working environment during curing to prevent dust adhesion. Meanwhile, stabilize the temperature at 60–75°F and avoid direct sunlight or proximity to heat sources.
Curing Test: After initial curing, the curing condition can be determined by a press test—press the edge of the product lightly with your finger; it is qualified if there is no indentation and no stickiness on the finger. After full curing, a hardness test can be performed (e.g., no scratches are left when scratched with a fingernail).
4、Summary
The curing time of deep-poured epoxy resin can be simplified as follows: under standard conditions (60–75°F (15–24°C) and a single-layer thickness of 0.5–1 inch), the initial curing takes 24–72 hours and full curing takes 5–7 days. If the ambient temperature is lower, the pouring thickness is greater, or a slow-curing product is used, the full curing time may be extended to 1–2 weeks.
The core principles are “follow product instructions + control environmental conditions + avoid one-time thick pouring” to ensure complete curing and compliance with performance standards.
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