Why is sandpaper not recommended for use on glue joints?

The choice that states sandpaper is not recommended for use on glue joints because it clogs pores and rounds edges highlights a critical issue when preparing surfaces for adhesion. When wood surfaces are sanded with sandpaper, the abrasive material can create fine dust and debris that fills the pores and fibers of the wood. This clogging prevents the adhesive from properly penetrating the surface, which is essential for forming a strong bond.

Additionally, using sandpaper can inadvertently round the edges of the joint surface. A rounded edge reduces the surface area available for the glue to bond, leading to a potentially weaker connection. Properly prepared joints should have crisp and clean edges to maximize surface contact between the adhesive and the wood, thus ensuring a stronger bond.

Other options, while they present valid concerns, do not address the fundamental problem associated with bonding surfaces for adhesive applications as precisely as the point about clogging pores and rounding edges. Therefore, this choice correctly identifies why sandpaper is not suitable for glue joints in woodworking and aviation applications.