My F-27 came with a mylar schreacher that had been left in the heat a bit too much. My guess is it was left furled in the sun often, as the leach and foot were faded. But all of the sail that was not directly exposed to UV would have been hot. The whole sail was delaminated. It was a shame, as it was a Smyth sail that looked fine fabric-wise, but all of the mylar had become delaminated. It appeared to me to be the effects of the sail baking in the heat. Not sure how long it took to get in that shape.