Because of its importance, the mixed viscosity of many deep-pour resins is captured in the summary tables of the “ 2023 Epoxy Resin Online Buyers Guide for Woodworkers,” when that information is provided by epoxy resin kit suppliers. The viscosity of most Deep Pour epoxy resins for use in river tables and thick castings are between 250 cps and 600 cps, mixed.The higher the cps number, the thicker or more viscous it is, and the slower bubbles will rise. Viscosity is usually measured in centipoise, or cps. First, Stokes Law also describes how much faster bubbles rise from a low viscosity (or thinner) resin vs. What can we do to minimize micro bubbles in resin? Several things.Meanwhile, the larger bubbles in epoxy continue to rise, though more slowly than at first, up until gelation occurs. They no longer are able to overcome the resisting force from the increasing viscosity, even before resin gelation. So, as the viscosity rises from low viscosity resin during cure to higher viscosity resin, micro bubbles in epoxy are the first to completely stop rising. However, from the image above you get the idea that small bubbles have less rising force than bigger bubbles in resin. After it gels, no more bubbles in resin can rise. The viscosity continually gets thicker and thicker until the resin gels and then hardens. As the reaction between the A-side and B-side of the epoxy resin mix continues, the viscosity increases. Micro bubbles in resin are also the slowest to rise for another reason.It turns out that lower viscosity is much more important than our intuition may lead us to believe, for “how to get bubbles out of epoxy.” Stokes Law is helpful, though, for quantifying the differences.Bubbles rise slower out of thick, highly viscous liquids like epoxy resin or honey. This is intuitive too: We all know: Bigger bubbles rise faster! We also all know that bubbles rise faster out of thinner liquids like water. An easy ‘science lesson': Stokes Law states that the Velocity of bubbles rising in a liquid is proportional to the bubble’s Radius squared, divided by the liquid Viscosity.#2 Bubble Blog: WHY use a lower viscosity resin, with a longer cure time? Because: BOTH are KEY, for “How to remove bubbles from resin!” Bigger bubbles rise faster than micro bubbles in resin: Stokes Law It can also be used in epoxy COATING applications (0.05-0.25”), with 4% PRO ACCELERATOR, for a 6-hour gel time, tacky and ready for a deep pour the next day.It has the longest gel time (~24 hrs.), the lowest exotherm for deepest pours (4”), is the clearest, and has the best UV protection: UV Absorbers + HALS.The BEST epoxy resin for woodworking, for deep pour applications like casting river tables, is PRO RESIN plus PRO HARDENER (185 cps, mixed, for the fewest micro bubbles). Slower gelation times allow a longer time for bubbles to rise out of resins. ![]() Bubbles rise faster from lower viscosity resins (thinner, less thick resins).If the above limitations are YOUR practical reality as well, then the ONLY way to do BETTER, is to buy low viscosity epoxy resin that gels slower, as professionals do, because:.Then they “pop” the bubbles in one of several ways (read on). FACT: Usually, professionals simply rely on bubbles in epoxy resin formulations to naturally rise to the top.FACT: Most professional woodworkers mix their resins fast, with a mixer on a drill, which whips in loads of bubbles.FACT: Most professional woodworkers do not vacuum-degas their epoxy resin mixes, especially if in production because it takes time.SUMMARY: If you’re the kind of person who wants to “cut to the chase,” then here’s the short version of all three blogs relating to bubbles: Use the lowest viscosity resins you can find that work in your applications, with the longest gel time. What to AVOID (Propane Torches!), and what to DO!.Removing air bubbles from the surface of resin pours.What to AVOID (Solvents, and Heating), and what to Do.Removing air bubbles from deep within resin.Fast mixing with a drill and mixer whips bubbles deep into epoxy resins!.#3 Bubble Blog: How to get rid of bubbles IN resin? How much faster do bubbles rise from lower viscosity resins? See for yourself!.Bigger bubbles rise faster than smaller bubbles.YOU ARE HERE! #2 Bubble Blog: Why Use Low Viscosity, Long Gel-Time Resins. How to totally AVOID bubbles in resin? 100%? Use Static Mixers!.Apply a seal coat to avoid bubbles arising from air in wood.How to best mix and dispense epoxy resins, AND avoid bubbles in resin.#1 Bubble Blog: AVOID BUBBLES When Mixing Resins!
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