#2 Bubble Blog: Use Low Viscosity Resins!

#1 Bubble Blog: AVOID BUBBLES When Mixing Resins!

  • How to best mix and dispense epoxy resins, AND avoid bubbles in resin
    • Semi-automatic mixer.
    • Hand mixing to avoid bubbles.
    • Apply a seal coat to avoid bubbles arising from air in wood.
  • How to totally AVOID bubbles in resin? 100%? Use Static Mixers!

YOU ARE HERE!  #2 Bubble Blog: Why Use Low Viscosity, Long Gel-Time Resins.

  • Bigger bubbles rise faster than smaller bubbles.

  • How much faster do bubbles rise from lower viscosity resins?  See for yourself! 

#3 Bubble Blog: How to get rid of bubbles IN resin?

  • Fast mixing with a drill and mixer whips bubbles deep into epoxy resins!
  • Removing air bubbles from deep within resin.
    • What to AVOID (Solvents, and Heating), and what to Do.
  • Removing air bubbles from the surface of resin pours.
    • What to AVOID (Propane Torches!), and what to DO!


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

  • FACT: Most professional woodworkers do not vacuum-degas their epoxy resin mixes, especially if in production because it takes time. (It’s always a good idea though.)
  • FACT: Most professional woodworkers mix their resins fast, with a mixer on a drill, which whips in loads of bubbles. Why? Because it saves time.
  • FACT: Usually, professionals simply rely on bubbles in epoxy resin formulations to naturally rise to the top. Then they “pop” the bubbles in one of several ways (read on).
  • 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:
    • Bubbles rise faster from lower viscosity resins (thinner, less thick resins).
    • Slower gelation times allow a longer time for bubbles to rise out of resins.

Solution? Lowest Cost ($59.99/gal. delivered + tax), BEST Deep Pour Epoxy!

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). 

  • 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.
  • 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. 

#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 

  • 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. You can forget the math. 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. Bubbles rise slower out of thick, highly viscous liquids like epoxy resin or honey. That’s all Stokes Law says.

  • Stokes Law is helpful, though, for quantifying the differences.  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 predicts: bubbles in epoxy, how to avoid bubbles in resin, how to remove air bubbles, best epoxy for no bubbles, how to get bubbles out of resin, and how to get rid of resin bubbles.

How much faster do bubbles rise from lower viscosity resins? Stokes Law:

  • A scaled relationship for bubble rise rate vs. size of bubbles is shown in the image below, per Stokes Law. It helps to gain perspective about the difficulty of removing micro bubbles in resin. 

  • Now, we can clearly see that when ”4X” sized larger bubbles have already reached the top of a liquid, “2X” sized bubbles are only 25% up, and “1X” sized smaller bubbles have barely begun to rise! Further, if there were any “0.5 X” micro bubbles in resin (not shown), those would barely be off the starting line.

  • This is why micro bubbles in resin are so difficult to remove

Alt. text:  It is much harder to address the question, “How do you get bubbles out of resin?” when there are micro bubbles in resin.
Micro Bubbles in resin rise MUCH slower than larger bubbles!

    • Micro bubbles in resin are also the slowest to rise for another reason. As the reaction between the A-side and B-side of the epoxy resin mix continues, the viscosity increases.  The viscosity continually gets thicker and thicker until the resin gels and then hardens.  After it gels, no more bubbles in resin can rise. However, from the image above you get the idea that small bubbles have less rising force than bigger bubbles in resin. 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. They no longer are able to overcome the resisting force from the increasing viscosity, even before resin gelation. Meanwhile, the larger bubbles in epoxy continue to rise, though more slowly than at first, up until gelation occurs.
    • What can we do to minimize micro bubbles in resin? Several things. First, Stokes Law also describes how much faster bubbles rise from a low viscosity (or thinner) resin vs. a thicker one. Viscosity is usually measured in centipoise, or cps. The higher the cps number, the thicker or more viscous it is, and the slower bubbles will rise.

    • The viscosity of most Deep Pour epoxy resins for use in river tables and thick castings are between 250 cps and 600 cps, mixed. 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 fact that half of the deep pour epoxy kit suppliers don’t report mix viscosity, shows they don’t grasp the importance of low viscosity. Yet it’s especially important in deep pour resins, where resin bubbles have a long way to travel vs. bubbles in coating resins, which are applied thinly.

    • The lower the viscosity, the faster bubbles rise from resin. It’s almost that simple! Lower viscosity is the ONLY way to speed bubble rise in resins without applying a vacuum.

    • Viscosity:  The graphic below compares the effect of viscosity on the relative  rate of bubbles rising, for five resins with increasing viscosity: 

    A vacuum degassing chamber is not needed with low viscosity resin.  Using low viscosity resin is the best answer for how to get air bubbles out of resin.

      Using low viscosity epoxy resins for deep pour river tables lessens the need for a degassing chamber.

      • The above figure shows clearly that the lowest viscosity deep-pour epoxy resin mix will have the fewest micro bubbles trapped in epoxy resin when cured if all else is equal. For example, we are assuming that all of the above resins have thesame gel time, the same size microbubbles, and only differ in viscosity.

      • The BASELINE case has a 185 cps mix formulation. This is the lowest viscosity deep pour epoxy resin mix reported (PRO EPOXY and PRO HARDENER, www.RiverTableEpoxyResins.com). Consider that here’s a microbubble size that JUST barely makes it to the surface of this low viscosity resin before gelation, and pops. In this scenario, the lowest viscosity (185 cps)  PRO EPOXY will have:

        • 41% fewer microbubbles than 260 cps resin mixes:
          •  www.Ecopoxy.com “Flow-Cast" and
          • www.MASEpoxy.com “MAS Deep Pour Epoxy”
        • 127% fewer micro bubbles than 420 cps resin mixes:
          • www.FGCI.com parent company to www.SuperEpoxySystems.com; “Super Clear 2.0”
        •  175% fewer micro bubbles than 510 cps epoxy mix:
          •  www.RyverEpoxy.com  “R-Cast 2.0”
        • 224% fewer microbubbles than 600 cps epoxy resin mix:
          • www.SpecialtyResins.com  “Epoxit Deep Pour"
      Low viscosity epoxy resin is the best answer for how to get bubbles out of resin. The lowest viscosity deep pour epoxy resin is PRO EPOXY and PRO HARDENER from www.Eco-nomicResins.com. Otherwise BEWARE the Microbubbler!

      NO! means NO! to MICROBUBBLES! 
      Protect the purity of your River Tables

      • You may be thinking, “Aw C’mon, So what? Hocus-pocus-gobbledygook! Does lower viscosity epoxy REALLY matter?” for 'How to get bubbles out of resin,'” you know, when REALLY making EPOXY RIVER TABLES?

      • A very well-respected leader making hundreds of epoxy river tables annually, has extensively used both EcoPoxy.com 260 cps “Flow-Cast,” epoxy AND SuperEpoxySystems.com “Super Clear 2.0” 420 cps epoxy mix. They see that Super Clear 2.0 epoxy entraps noticeably more microbubbles than Eco-Poxy, just as predicted from theory. Trapped microbubbles are a REAL problem for Super Clear 2.0.  So, YES! It REALLY matters! (And it’s the BEST way to get rid of bubbles in resin!)

      THEORY = FACT, for micro bubbles!

      • If you want to know, “Which is the best epoxy for no bubbles?” almost all you have to do is to compare mix viscosities. The Best Epoxy for no bubbles is always the one with the lowest viscosity (as long as gel times are similar).  There’s no need to run an experiment. It’s just Physics gobbledygook!
      • The best buy for deep pour epoxy resin kits is from www.Eco-nomicResins.com: PRO EPOXY and PRO HARDENER. It’s also the epoxy with the fewest bubbles.  It’s the lowest viscosity epoxy. It’s the epoxy with the best UV protection. It’s the epoxy with best price. It’s the epoxy with the deepest pour. Deepest pour epoxy. Thickest cast epoxy. Coolest epoxy. Lowest exotherm epoxy.Fewest Microbubbles! “PRO EPOXY and HARDENER” with 185 cps mix viscosity from www.Eco-nomicResins.com, has 41% fewer microbubbles than even “Flow-Cast” while also being far more economical!  $59.99/gallon delivered with state tax, vs. $116.28/gallon for EcoPoxy “Flow Cast.” OUCH!

      • As costly as that is, you may as well eat off your arm and a leg. Mmm-y!  Dang! – Ouch, mmm! Ouch! – Ouch!! It’s a "Hurty frog-leg meal!"

      • BEWARE! “Super Clear 2.0 traps 127% more microbubbles  than lower viscosity PRO EPOXY and PRO HARDENER from Eco-nomicResins.com.

      LONGER GEL TIMES also allow more bubbles to escape!

      •  Consider two deep pour epoxy resin mixes having the same starting point viscosity, but one gells in 6 hours (as many do), and the other gels in 24 hours, as the best deep pour epoxy resins do.

      • The slower gelling deep pour epoxy resin will have 400% more time for bubbles in resin to rise to the surface, and will also have four times (400%) fewer microbubbles trapped after cure.

        • This is one reason it is relatively easy to degas deep pour epoxy resins used in river tables just by letting them sit! They have longer gel times than coating formulations (usually just 45 minutes or less), as required to allow the heat-of-reaction to dissipate from THICK epoxy castings.

      • One well-known vlogger, deep in the black forest, recommends cooling mixed resin, to slow the cure and give bubbles more time to rise. However, cooling resins also greatly increases their viscosity, greatly slowing the rate of bubble rise. We don’t pretend to know everything. Depending on your resin system, the trade-off may be worth it – he’s got loads of experience. You have to respect that.

      • However, it’s simpler and better overall to start with the lowest viscosity, slowest-curing resins available, especially for deep pours.
        • That's: PRO EPOXY and PRO HARDENER from Eco-nomicResins.com:  185 cps mix viscosity PLUS 24 hour gel time.

      • The thinner the pour (as in inches or cm), the easier it is for bubbles to rise to the surface. Coating resins are rarely applied over 0.125 inches thick at one time, vs. 1-3 inches for deep pour resins.

      • This is one reason why epoxy coating resins can be higher in viscosity than deep pour resins. Epoxy coating kits are typically 1,000-2,500 cps when mixed (vs. 185-600 cps for deep pour epoxy resin kits, mixed.) Low viscosity epoxy resin matters most for deep pour resins.

      • The main reason that coating resins usually are usually formulated with higher viscosity is that users often want a "high build." High-build coatings allow one coat to create a shiny, glazed glass-like finish. If the coating resins were too thin, they’d just run off the tabletop or bar top (unless dammed).

      • On the other hand, coating resins usually are formulated to cure gel in 30-45 min., vs. 6-24 hours for deep pour resins, so they also have far less time for bubbles to rise to the surface. It’s all a matter of trade-offs.

      • Fortunately for you, Eco-nomicResins.com Clear Deep-Pour PRO EPOXY and PRO HARDENER, can be converted into an extremely low viscosity coating resin as well (<200 cps) by adding up to 4% PRO ACCELERATOR. Gel time drops from 24 hour to 6 hours. Still slow, but perfect if you’re using it for a seal coat on your river table and intend to do the final deep pour the following day. It’ll be mostly cured but still tacky the next day, for great adhesion to the final deep pour.

        • LOW viscosity and long gel time: There won’t be any trapped micro bubbles remaining in this coating resin!

      “The end:”  #2 Bubble Blog: Use Low Viscosity, Long Gel-time Resins.


        #1 Bubble Blog: Avoid Bubbles When Mixing Resins.

        Discusses how to mix and dispense epoxy resins while minimizing or 100% avoiding all micro bubbles in the first place.

        #2 Bubble Blog: Use Low Viscosity, Long Gel-time Resins.

        Discusses the importance of low viscosity resin and long gel times for how to get bubbles out of epoxy.

        #3 Bubble Blog: How to Get Rid of Bubbles IN Resin.

        This blog on “How to get bubbles out of resin, discusses the resin degassing chamber, as well as how to get rid of bubbles in resin SURFACES.


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