What is rubber surfacing micro foaming?

Micro foaming happens when the binding agents in a Rebinder or any conditioning agents come in contact with moisture in the EPDM granules. All polyurethane binders don't get along well with water. This is why we always pick a dry day to do a fresh poured in install, repair an existing surface or rebind a surface. This part seems to be easy for most installers. Just look at the weather forecast and pick a dry day. The part that is a bit trickier is making sure the surface is completely dry. 

poured in place rubber microfoaming

In the picture above you can see micro-foaming from an aliphatic based Rebinder. An aromatic based rebinder will produce more of a yellowish foam. (Shown in the picture below). If you take a microscope to the area affected you will actually see tiny bubbles. The only way these bubbles occur is if moisture is involved. It's a chemical reaction that is completely expected when these two components meet. 

Microfoaming in rubber flooring


What to do to avoid micro foaming while maintaining my rubber flooring?

  1. Pick a nice hot and dry day to rebind.
  2. Don't start rebinding too early in the day. Dew and moisture might still be present .
  3. Check under decks and in shady areas for moisture.
  4. If you are expecting rain in the next 6 hours, don't rebind.

 What to do when you experience micro foaming

  1. If it's not that bad, leave it alone. The foam area is an exposed surface and will be take care of by foot traffic
  2. If it's too unsightly, you can use a plane sander to sand the area
  3. You can power wash the area. But be careful not to dislodge granules. Use a wide angle nozzle 

A couple things to note. One is that some installers will push the roller too hard and will leave squeak marks on the surface. That's not micro-foaming. That's excess material, which will also go away with time and foot traffic. The other is that if you ever need to sand the affected surface, you will not have to rebind again as the system is still flush with rebinder between the granules. We don't care as much about the top of the granules as that thin layer of rebinder is removed by foot traffic anyway. Finally, If there is a sprinkler system in the area and the water has a high lime content, you might see a film of whiteness on top of the surface. This can happen a few days later. The film looks very different from micro foaming. Something to watch out for.

If you have any questions about maintaining your playground rubber surface or pool deck rubber surface, please give us a call at 203-659-0456 or email us at info@trassig.com