How to know when to rosin my bow

The bow hair does not have enough rosin if the bow does not slide easily and produces no sound or just a slight, thin sound. But if the bow is very scratchy, then there may have been too much rosin in it. Optically: with a thumbnail, you can scrape through the bow fur.

because of the importance of consistency in data collection. but we have to evaluate the resource or information, and not just accept what is posted online since information available on the internet is not regulated for quality or accuracy.