Thick Pour Resin Compared To Table Top Or Resin Art Epoxy
Deep pour casting resin, sometimes called river table epoxy resin is often a thinner material when mixed which allows for thicker pours. This is the simplest of terms, there is actually quite a bit more which makes the two very different epoxies. Each type of epoxy serves a different use and should be used specifically for those uses.
Deep Pour Resin Characteristics
There are many characteristics which make thick pour resin unique compared to a coating epoxy. Most notably, and most obvious to the end user, is the mix ratio. Casting resins which are meant for thick pours are often 2:1 by volume mix ratios. Normally, this is two parts base resin to one part curing agent or hardener. Coating epoxies, on the other hand, are often 1:1 by volume mixtures. Occasionally, thicker pour resins will come in varying ratios such as 3:1 or include a different type of catalyst which may require only a few drops.
Reaction & Cure Time
Because the ratios are not evenly proportional, the reaction and cure time of deep pour is much slower compared to coating epoxies like table top epoxy. Table top epoxy will often begin reacting as soon as the two parts are mixed. In fact, these types of epoxies must be poured immediately after completely mixing. Leaving large amounts of mixed epoxy in a container will often result in an accelerated reaction which causes the epoxy to cure too fast. Coating epoxies will begin to gel in roughly 20-30 minutes, tacky to the touch in 4-6 hours and hard to the touch in 12 hours. A full cure can take up to a week to cure throughout the layer. Casting epoxies take much longer to react and cure. The heat release or exotherm is much lower on a deep pour which is critical to thick pour application. Casting epoxies may take up to 48 hours to cure. Because these take so long to cure, it is very important to keep the project in a clean, dry, dust-free environment throughout the entire cure process.
Heat & Exotherm
Heat production is a direct result of the chemical reaction caused by combining the two parts of epoxy. The reaction with bar top epoxy (coating epoxy) occurs almost immediately after mixing. User may even notice the mixing container warm up slightly while mixing for 3-5 minutes. The epoxy also may appear hazy while mixing while the two parts bond. Properly mixed epoxy needs to be poured directly after mixing or the epoxy will continue to product heat. This reaction is compounded with more mass. By pouring the epoxy immediately after mixing, the mass is reduced which allows the heat to dissipate. Casting epoxies react much slower and produce much less heat. Reaction and cure times can often take 36-48 compared to 12-24 hours with coating epoxy.
Max Pour Depths
Maximum pour depth per application is dependent on heat production as the reaction occurs. If table top epoxy is poured too thick, heat will build up and cause the epoxy to discolor, crack, bubble, etc. Therefore, the maximum recommended pour depth on coating epoxies is usually 1/4" or less per application. Because heat production is much less with deep pour epoxy this can be poured much thicker. Brands vary in recommended max pour depths but several offer 2" pours, some can be poured even thicker.
River Table Epoxy Resin
When choosing an epoxy for a river table or a live edge product, the intended use must be defined. If the river is deep, 1/4" or more, then deep pour resin must be used OR a table top epoxy must be layered. Most river tables are much thicker/deeper than 1/4", therefore, most craftsmen and craftswomen choose to use a thick pour resin to fill the river. However, thick pour resin is not intended for coating applications. Deep pour resin does not possess the self leveling properties of a coating epoxy.
Therefore, a river table project may also require a table top epoxy to coat the top, after the river has already been filled/cured. Needless to say, the deep pour epoxy should be used for deep/thick applications and table top epoxy should be used for coating applications. However, thats not to say that a coating epoxy cannot be used for casting applications. Coating epoxy can be used for casting projects, even river tables, but the epoxy must be poured in layers. Normally, the next layer can be poured when the layer prior is tacky to the touch (with a gloved hand). This is often four to eight hours depending on temperature. On the other hand, deep pour resins should not be used for coating applications. Because thick pour material is much thinner it will not level or build up as thick as a coating epoxy. River tables and deep cast will often require a dam/frame to contain the epoxy so that it cannot flow out of the intended area.