"Agki Strodon" wrote in message
news:4TCEc.20861$bs4.13057

Spaces in glued up joints produce weakness because theres no glue in the
spaces to form a bond.

Now you are showing signs that you might understand the point that I was
trying to make.

You said,

"A roughed up surface holds better than a smooth one because there's more
glue in the between pieces volume, ain't it?"

Roughed up surfaces often cause spaces in the glued up joint. A smooth
surface is Ideal for glue.