Description

MACt Defoamer (20KG)

Description:

When GRFCs are mixed, often air is entrained and forms bubbles within the cured GRFC. A small amount of air is not a problem, but when the bubbles group together the strength and surface finish can be damaged. In the more extreme cases this can ruin the GRFC or the finish totally.

The big question is why does the GRFC have air in it in the first place? The answer is surprisingly due to the polymer and plasticiser that’s used. Most polymers either come as an emulsion or as a redispersible powder. To make an emulsion or to get the polymer to disperse into the water surfactants are used. It’s a different story for plasticiser as they are wetting agents in their own right and will entrain air often used to enhance the plasticising effect.

No matter how the air is drawn in, the effect is the same. The bubbles form a two-layer boundary film on their surface between the mix water and the trapped air. This film attracts other bubbles through Van der Walls forces causing the bubbles to cluster together forming rafts as the film between the bubble does not break down.

To improve the performance of your GFRC it a good idea to get rid of the air, and to do this you add a MACt Defoamer (20KG). Defoamers can be of a number of different types depending on the where your foam is and how you need to get rid of it. In a GFRC the foam, even though its on the surface of your piece in the mould, needs to have the air in each adjacent bubble to join up so that the air becomes big enough to float up through the GFRC and escape.

At MACt we use a special polymer that forms a hole in the film between the bubbles causing the bubbles to merge together to form one bigger bubble. This happens time and time again until the bubble grows so large that it floats up through the GFRC and escapes.