Last weekend I bought a Infinity longboard “seems fairly new” to make a template and noticed it has black glue lines on each side of the stringer. It looks nice but I am curious. There is nothing but a serial # on the board.
My question is " anyone might know the blank manufacturers that do this?"
Clark Foam use to do this. You could specify the color of the glue. I think US Blanks also does this currently. I am sure that most manufacturers that do custom rockers should be able to do this.
All the blank companies will put some color in if you ask.
It is just resin with some pigment, easy to do but it really makes a light(bass wood) stringer stand out. I request it a lot on my boards it is free and adds a lot in my mind anyway, not real found of blue, green or red, but black is nice.