Streaks happen for one reason: the surface dries before the cleaning solution gets squeegeed off. Cheap services rush — they spray, swipe, leave. The solution dries faster than they work. The streak-free formula has three parts. First: right solution. Biodegradable, no ammonia. Ammonia-based cleaners (the blue stuff at Canadian Tire) leave residue when they dry. Pro solutions self-rinse. Second: right tool. Squeegee with a clean rubber blade. Microfiber for finishing edges. Never paper towels — they leave lint and friction-marks on glass. Third: right pace. Top-to-bottom in overlapping S-strokes. Wipe the squeegee blade between strokes. Finish edges with a dry microfiber. Why we guarantee streak-free: two-person crew works systematically — one washes, one finishes. Water-fed pole for upper floors uses pure deionized water that dries spot-free without squeegee. Walk-through inspection with you before invoice. 7-day callback guarantee — if you spot a streak after we leave, we come back. What about hard water stains? Mineral deposits from sprinkler overspray or rain runoff need a separate treatment. Quote add-on after assessment — most stains under two years old come off cleanly. How often to clean Toronto windows: twice yearly is standard. Lakefront homes (The Beaches, Mimico, Long Branch, Port Credit) twice yearly minimum, sometimes three times.