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Common Resin Issues

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Film or oily surface after epoxy has cured

The cause is most likely due to a side chemical reaction of moisture (humidity) in the air, interacting with a curing agent (also common when the ratio's are not maintained correctly). This is known to epoxy chemists as "amine blush" or "amine bloom". Avoid conditions where moisture is coming out of the air as temperatures drop. Also can stop subsequent products from fully curing, or performing correctly and yellowing unless removed properly. To remove, thoroughly wash the cured epoxy with clean warm water, all-purpose soap and a stiff brush. Aggressive solvents like acetone will not remove the blush. Unfortunately doing resin work at night are exposing epoxies at the lowest temperatures and the highest humidity further compounding the problem.

Fisheye or creator effects

Substrate contamination is the most common problem that causes fisheyes and pin holes in epoxy coats. Dust, dirt, wax, silicones and even the oil form your fingers when touching the part prior to coating with epoxy will deter epoxy resins from laying flat and curing with a perfectly smooth surface. Additionally, trying to extend the epoxy by brushing it too thin, will create a creator effect where the epoxy shrinks away from the thinner parts.


Bubbles in epoxy

There are several ways and several types of bubbles. When bubbles appear in a freshly applied epoxy coating, the most common culprit is something called "outgassing". Outgassing is a site condition that allows air or gas from the concrete (or timber) substrate to escape in excess and cause blisters, craters, bubbles or pinholes this is called off-gassing and it results in air bubbles in the resin, sometimes hours after you have poured and torched. To help prevent this you need to pre-seal your work, prior to resining. If you are casting into molds, choose a resin that is designed for casting (the long 'open' time of casting resin is to allow bubbles to rise to the surface from such a deep casting. The shorter the set time the less time for the bubbles to get out of the system. Use a flame or IPA to release surface bubbles. Many of our non-toxic, FDA Food Grade epoxies require no special requirements as they are self degassing, but with some other normal resins the cold weather will hold bubbles when mixing (simply heat resin to over 25 deg C in hot water prior to mixing helps this)

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Snail tracks on the cured resin

Surface is smooth but has what looks like snail tracks is usually a direct result of not fully mixed resin. The ratio may be correct but the hardener is not mixed correctly. Picture in your head that part A as being white paint, while the part B is black paint. If you add the black into the white and partially stir it then you will get streaks of black within the now mostly grey paint. If fully mixed then you would have grey paint only with no white or black visible. When stirring your epoxy, scrape the sides because that is possibly where the streaks are coming from.

Cloudy epoxy - after using

Cloudy or dull epoxy is typically caused by excessive moisture. Specifically, moisture from excessive humidity in the area where the epoxy was applied or excessive moisture in/on the application surface. It can also be caused by moisture that has gotten directly into the mix of epoxy, but this is a rare occurrence. When the epoxy turns white in some areas it suggest that your epoxy system contains what is called "blushing". This is usually caused by high humidity (moisture content in the air) when the coating was applied or your substrate was not totally dry at the time of application. A more common situation is that the user mixes the epoxy in a late afternoon or evening? They applies the resin and go to bed? What happens is that the night is the coldest part of a 24 hour day. Epoxies do not work well in cold conditions (well known and documented). So during the long cold night? The epoxy components are exposed for a long period to the atmosphere and can absorb gases like Carbon Dioxide. This then alters the surface characteristics. Cold weather and high humidity are great contributors. Solution? If you must operate this way? Then heat your resin to about 28 deg C, mix and apply. Keep the room warm and dry.

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Sticky spots or uncured resin

The cause is most likely due to not fully mixing the epoxy even if measured at the correct ratio or alternatively mixing epoxy that has not been measured at the correct ratio (or the weather is too cold to effect a cure). To remove, manually dig out all the sticky resin. Wash with aggressive solvents like acetone and when dry, grind or sand the surface to apply a second coat of epoxy. Curing of epoxy takes a lot longer in winter than in summer. In cold nights at below 10 deg C, the epoxy will stay wet for days until the temperature rises.

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