One of today's jobs has a rookery right by the back windows. As you can imagine they are always a mess. Never had an issue just using cold pure till today. One bay window luckily ground floor was properly covered. Gave it a good scrub most of it came off. However it's left behind about a dozen thick sticky deposits. They are almost like silicon but realy hard. Only had a plastic scraper with me an it snapped. I typed soaking with ubick. No effect. Got to go back Monday with another scraper. Or can enyone offer an alternative.