The Secret Belgian Binding (originally named Crisscross by its creator, Anne Goy), is a versatile structure that begs to be experimented with. You can change the colors of the threads in the weaving pattern, paint the covers, collage them, cover them with bookcloth. I photocopied a copy I had of the Why Cheap Art? manifesto from Bread and Puppet Theater and used it as my covering material, both over the main boards and over board scraps. I sealed it with acrylic gloss varnish. My post on Secret Belgian Binding is here. Instructions are featured on pages 159-161 in Making Handmade Books: 100+ Bindings, Structures & Forms.
Comments
Here are a few thoughts for a tighter binding:
—Make sure your spinepiece is not too wide or add more signatures to fill it.
—Weave the covers with enough space to get your needle between them, but not more, then keep it tight as you go.
—Try either a smaller book dimension or more holes (an even number only: try 8 instead of 6), then sew around the extra pair like you do for the other two sets, leaving the ends free, as usual.
—Make sure you are using a curved needle.
—Check the stitches and tighten them one by one before you make a square knot or kettle stitch.
Best wishes and keep trying!