Looks incredible shell! Wood glue will seal it. I did a grout background on my 125 way back when, but the wood glue I used to seal it with cured with a yellow tint. I never did like it. Personally, I prefer 2 part epoxies for anything that will have water running on it. It's a lot tougher and doesn't submit to erosion as easily as other compounds. Of course, that's only if you have it available to you.


Education is the most powerful weapon we can use to change the world ~ Nelson Mandela