Here’s an innovative idea for putting ink on glass. This avoids using a plastic substrate to adhere to the glass. But not nearly as easy and convenient to use.
In the end, Speedball’s nontoxic water-soluble inks, though not endorsed for window applications by the manufacturer, held up well while being a more environmentally responsible choice than vinyl for the same job. Graphics applied to windows in this way are easily removed with a common scraper to get ready for new image application.