soot
炱 centers on the dark, powdery residue left by fire: soot.
炱 combines 台 (a phonetic component) with 火 (fire), suggesting a word for soot or fire residue with a sound related to 台.
Fire 火 under a platform 台 produces black soot that rises and coats the platform above.
For タイ, imagine a tie-dyed cloth getting covered in soot from a fire: tie -> タイ, and the soot ruins the tie-dye pattern.