I bought these three years ago and used them to glue over 100 picture frames. Yes, there is no guide for this, but you will find out for yourself (Google, YouTube). Start with some pressure so you can make small adjustments, then increase the pressure, wait 30 minutes and your picture frame is ready to sand. With a little practice it becomes very easy to use and the results are fantastic. Over the years I've also found other unexpected uses for them, such as gluing the body for a flux capacitor