In this video I show how to fill the grain with pumice powder, this process is very easy to do and once you have filled the grain you can go on to polish your guitar.
To build your own classical guitar in your own workshop using my step by step 40 hour plus video course series visit:
https://onlineguitarmakingcourse.com
If you are interested in building a guitar in my workshop in Spain all the information that you will need about the 4 week course is available at:
http://guitarmakingcourse.org