Question

You have to explain the observation of the following experiment. Both the experiments below have the same observation, so you can use either. But please do not spam and answer only if you know. You can guess in comments only.
Experiment:
Take a printed paper, preferably with large or bold letters in black ink. Take a magnifying glass and focus sunlight on a letter [Carefulllll, do not burn it]. Now slowly hover the letter under the focus. The letters shine when placed in appropriate lighting conditions. But this does not happen always.
OR
Take a printed paper and iron iron it using a cloth iron. It may shine.

Answer 1

in the first experiment.. this happens because sun light is refracted at such a very sharp angle