A few times in the last couple of months people have raised eyebrows when they have seen me using black PLA. Its not been through choice, COVID-19 for whatever reason has made printer filament hard to come by, with white PLA especially scarce.
The other day, whilst testing differential thrust on the Grumman Mallard, I had a small incident. I hadn't affixed the wing to the fuselage properly, the wing moved with the differential thrust and the prop took a few bites out of the fuselage. Whilst examining the fuselage to see if I could save it for the maiden flight I left the wing in the sun. Its was only 22C outside but was a bright day...
After literally only 5 minutes in the sun the darker colour PLA has warped and deformed, not too much that the model is dead, but enough in 5 minutes to make me think twice in future. It doesn't seem to be temperature that is the problem but direct sunlight. Even grey PLA deformed, the orange PLA however remained unchanged.
So, to all those who raised eyebrows about my choice of dark PLA, you're absolutely right!
My advice going forwards, use light colours where possible, if you can't, don't leave your models in direct sunlight.