I have blessed candles that are 100% beeswax, but when I asked the SSPX priest to bless a small box of wooden matches he all but laughed out loud and said there was no blessing for the matches, and the candle should light itself in case of the 3 Days. I felt pretty dumb, especially since I had gone to the trouble to decorate the matchbox with a picture of OLF.
He shouldn't have basically laughed at you for asking an innocent and sincere question. Laughter and mockery are what demons do to demoralize or alienate you. And I never heard of any part of the 3DD prophesy that states the candles will light itself. People still need to light the candles which will remain lit and uninterrupted, if you follow the other instructions of prayer, covering the windows, not looking outside, etc.