I remember reading years back in the old SPI forum Barry mentioning the chemical name of what the flex additive actually is. And he also pointed that it stays on the paint for only a few months. I kinda figured it was one of those products that companies like to sell just for the sake of making some extra coin. I have no idea if it's snake oil or if it has any real value to the quality of the paint job.crashtech said:Standox's most modern 2K products still require the addition of a flex additive (15% before activation) so I'm not sure what to think about the whole flexibility thing sometimes. I know there are a lot of primers out there that shouldn't be used on flexible parts.