Hi there, can you use the copper oxide between two pieces of glass dry as it is !

Yes, you can use dry copper oxide in between two pieces of glass. If you want fine details you can use inclusion pens to draw on your glass, then use a brush to cover copper oxide onto your piece. Glass Schools Metal Inclusions Course goes into more detail which you can find here: https://www.glass-school.co.uk/courses/course-metal-inclusions