Planking & caulking effect

After having cut the deck planks in the appropriate length I tried some different techniques for the caulking effect.

In the end I decided for a black piece of (0,2 mm thick) cardboard glued on the planks as being the most reliable one with has an uniform look and looks good at the same time.

testing why doesn't is show

Planks cut in length

covering the cardboard with white carpenter glue

Position the planks "carefully" on the cardboard without using to much movement 

Apply not to much pressure on the planks until the glue has dried

Gently "cut" (several times and without using too much pressure) in between the planks using a sharp scalpel blade until the cardboard is cut 

This will be the result..