Stupid newb question #162

If, for example, epoxy-based lightweight sandable filler is laid over still-green fiberglass & epoxy, where does the amine blush go?

What happens to amine released from the epoxy-based lightweight filler?

I realize amine is not an issue in the above scenarios, but I am just curious what happens to it.

Curtis

 

Amine blush doesn't go anywhere, it doesn't have legs, though you can smear it around with solvents or even your hand if you want.

To be more technical, blush forms under certain conditions with most of the usual formations of epoxy that we use, even the ones that are supposed to be blush free. Basically it's a byproduct of a reaction with the environmental conditions, which can form on the surface of curing epoxy. This can be amplified with over or under mix ratios, placing the the phenol or glycol side out of balance, so some residual material reacts on the surface, typically because of moisture vapor.

If you place a fairing compound over still chemically active epoxy, the blush from the underlying epoxy will not form, because it's covered by the fairing compound, protecting it from environmental reaction. Of course, this assumes a blush hasn't yet formed. If it has, then over coating it with fairing compound can understandably, cause issues with the subsequent bond.

 

Thanks, Paul, that makes sense.