I have made a few End Grain Cutting Boards lately following the stanard procedures. I glue up panels of contrasting woods (mesquite, maple, cherry, purple heart, walnut and etc.) using Tite-Bond III, plane the panels so that they are flat, rip them into 1-1/4" sections and then glue and clamp them together with Tite-Bond III for a minimum of 24 hours.
Then using a combination of a Random Orbital sander and a wide belt sander and I finish them to 220 grit. I go through 60 grit, 100 grit, 120 grit, 150 grit and end with the 220. I know that I have skipped a grit or two but I am using what I have. By the time that I am finished with the sanding the board is very smooth and I am satisfied with the results.
To finish it I use mineral oil and parafin wax mixed approximately 6 to 1 and I apply 5 or more warmed coats. No here is where the problem comes in. About the time that I am finished with the mineral oil finish I can actually feel the glue lines. How can I avoid or eliminate this? Do I need to wet sand the mineral oil finish as I am applying it? What is causing this?