Found a picture of my half baked sunflower oil thermal stressing "experiment"
I stuck the printer paper on my (dirty) office window to get some backlighting (the black dot at the top is some Blutack) but the sun was setting, so its rather dark.
No proper laboratory equipment was harmed during the making of this picture.
I used half a drinking straw full of Sunflower oil, in a (washed-but-used) aluminium custard-tart cup, on a hotplate, quenched before sampling by floating the cup in a dish of chilled water.
Sampling used the end of an empty ball-point pen tube, dipped and then brought to the surface of the oil, and left on the surface of the printer paper for about 3 seconds.
I used SFO for a first look because I assumed I'd be likely to see an effect on a short timescale, and I was doing it in a kitchen. The dish was just on the smoke-point of the oil, but I dunno what its actual temperature was.
Spot diameter decreased over the time course, probably due to viscosity increase, though this probably also reduced the volume of sample transferred.
The two later time (100 and 140 minutes) points were also noticably darker in colour, but there wasn't much structure in any of the spots.