I have been asked recently what tool I use to prepare groundwork in preparation for veneering. It is generally good practice to tooth glue faces for improved adhesion of veneer and mouldings etc. (when using horse sauce), but I am hesitant to say I use a ‘toothing plane’ because there are different styles of toothed blades available with totally different purposes.
A toothed blade (that is, a blade with coarse teeth like your corn-pipe-smokin’, hog-chokin’, cousin-pokin’ friend Billy Bob) is not the tool for this job. A toothed blade is useful for taming the surface of gnarly wood prior to final clean-up with a smoothing plane or scraper, but the broad teeth can create furrows in groundwork wide enough to crackle some veneers as the glue in the furrows shrinks and pulls the veneer down. These toothed blades are used in bench planes and usually cut at an angle of around 45°.
The blade best used for preparing surfaces for gluing has a finely serrated edge that creates a series of fine scratches to which the glue will grab tenaciously, but which aren’t wide enough to have any detrimental effect on the veneer’s surface. These saw-tooth-like blades are used in scraping planes at angles between 0° and 25°.