The most troublesome problem during the application of deep pour epoxy resin is cracking. Cracking not only affects the appearance of the entire project, but in serious cases, it can directly render the whole project or work unusable. For beginners who are just getting started, they follow the tutorial step by step, so why do cracks still appear?
Today, Jinhua will analyze the common causes of cracking in deep pour epoxy resin and how to effectively avoid it.
First, the most common cause of cracking: inadequate sealing treatment of the substrate. For example, when making a river table, we use wood, which usually needs to be dried, cleaned, and then sealed. Wood contains a large number of internal pores; if it is poured directly without sealing, the wood will absorb the resin, resulting in uneven shrinkage, bubbles, internal voids, etc., all of which may lead to the appearance of cracks.
Second, the common mistake we often mention made by beginners: the single pouring thickness exceeds the product limit. Many people are eager for quick results (especially beginners), wanting to minimize the number of pours to shorten the project completion time. Each deep pour epoxy resin has a maximum pouring thickness limit. During pouring, we should try not to approach this limit to effectively prevent cracking. Sufficient interval time should be reserved between two pours, generally 6–12 hours, until the previous layer of resin is initially cured and the surface is dry and tack‑free before pouring the next layer.
Third, the mixing ratio of epoxy resin and hardener. There are three points to note here: first, a precise digital scale must be used for weighing to ensure an absolutely accurate ratio; second, after mixing, stir slowly and thoroughly without dead corners to fully blend the epoxy resin and hardener; third, the amount of raw materials mixed at one time should not be too large — the larger the mixing volume, the faster the exothermic speed, and the more likely temperature runaway will occur.
Fourth, the issue we often mention: temperature and humidity. Temperature has a great impact on deep pour epoxy resin. Excessively high temperature accelerates the reaction and causes rapid temperature rise, resulting in cracking. Excessively low temperature prolongs curing time and causes incomplete curing. Excessively high humidity causes internal clouding and poor adhesion. The optimal temperature is between 20℃ and 25℃, with humidity controlled below 70%. A good working environment can greatly improve the success rate of the project.
Fifth, we need to allow sufficient curing time for the project. Many people are eager to demold, sand, or apply load once the resin surface is solidified, not knowing that the interior of the resin is not fully cured and the internal structure is still unstable. Premature operation will damage the internal structure and cause cracks. It is recommended to let it stand for more than 48 hours after pouring before demolding, continue curing after demolding, avoid heavy pressure, impact, and sanding within 7 days, and do not place it in a high‑temperature or direct‑sunlight environment to prevent repeated stress from thermal expansion and contraction. Full curing takes about 7 days. Only after full curing should subsequent operations such as sanding and polishing be carried out, so as to ensure the strength and integrity of the epoxy layer and avoid later cracking.
Frankly speaking, most problems encountered with deep pour epoxy resin, such as cracking, bubbles, yellowing, etc., are related to substrate treatment, single pouring, environmental factors, mixing ratio, etc. As long as we grasp the relevant step details, we can improve the success rate of the project.