I have been asked recently what tool I use to prepare groundwork 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° (fig. 1).
Fig. 1. Toothed blade for use in a low-angle bench plane. (Veritas)
Fig.2. Broad furrows created with a coarse, toothed blade (click to enlarge).
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° (fig. 3).
Fig. 3. Finely serrated blade for use in a scraping plane. (Veritas)
Fig. 4. Scored surface created with a serrated blade (click to enlarge).
Jack Plane
Pegs and 'Tails 
Glad I saw this. I was going to try emulating some of your work with a toothed blade for my LA jack.. I only see antique tools with this tooth configuration.
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Old scraper planes such as this one crop up regularly at all your favourite on-line auction sites. Lie Nielsen and Lee Valley both make scraper planes with serrated blades; though LN’s 18 TPI blade would be my choice (it also fits the LV scraper plane).
JP
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Just a couple of observations…….
Recently, I made myself a veneer hammer and had a go at veneering with hot hide glue. I found the veneer adhered better when the substrate was toothed and better still when the veneer is toothed, too. Toothing the commercial 0.6mm thick veneer was done carefully and with the grain. I have never read or heard of toothing both surfaces before.
I soaked a box made in the latter half of the 1800’s in boiling water to dissolve the glue with the aim to see how it was constructed and to effect some repairs. The substrate was not toothed but the thick veneer (about 1.0mm) was rough on the glue side. To me it looked like it was a sawn rather than sliced veneer and the rough marks looked like saw blade marks rather than toothing plane marks.
And a couple of questions………….
Is the toothing of the substrate (and possibly the veneer) only of benefit when using hot hide glue and hammer veneering? (My reading suggests when using modern glues the surfaces should be smooth and flat to ensure a good bond.)
Jack, when you repaired veneered wooden articles was toothing evident on the substrate?
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I should emphasise, the period copies I make employ veneer ranging in thickness from 3/64″ (1.2mm) to 3/32″ (2.4mm). Thicker veneer can occasionally be difficult to hammer so any advantage is welcome and it’s robust enough to be toothed
I wouldn’t tooth veneer less than 3/64″ (1.2mm) thick. At that thickness, veneer is very pliable and easily laid it’s just not necessary to tooth it; plus it’s fragile and could easily be damaged by toothing it. Good glue alone is usually all that’s required to pull modern thin veneer down successfully.
I agree, sawn veneer’s rough surface is preferable to modern knife-cut veneer’s smooth surface. Roughing the glue side of the veneer lightly with 40-grit paper can be of benefit.
I have no experience of veneering with modern adhesives, so I can’t really comment on their efficacy, but as they work entirely differently to animal glue, I can’t imagine there would be any benefit to toothing either the groundwork or veneer when using them.
As a restorer, I frequently encountered toothing on both the groundwork and the under side of the veneer.
JP
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I don’t EVER want to meet that Billy Bob…
And thank you for the information, it’s one more piece of the puzzle.
– John
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Jack, In the post you speak of not using a corse toothed blade, then mention on the LN you would choose the 18 tooth when a finer 25 is also availible, would it be that the 18 could also be used to level figured woods, or is the 25 too fine a tooth ?
Joe
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Lie Nielsen describe their 18 TPI scraper blade as “coarse” (the 25 TPI blade is termed “fine”), but in comparison to a ‘Billy Bob’ blade it is very fine indeed. LN recommend their serrated scraper blades “for working exceptionally difficult grains” – and I have used mine once or twice for just that purpose – but I believe it’s a better groundwork blade than a grain-tamer.
I was given a Lee Valley scraper plane with a 25 TPI blade and found it too fine for veneering (hence I know a Lie Nielsen 18 TPI blade fits the Lee Valley plane).
JP
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“One more thing”… Would you choose using a low angle plane with a toothed blade or perfer the scraper planes with the toothed blade. I have the experience with a L/A plane that even with a toothed blade left enough tearout that it made final smoothing difficult. but that was on an “un-veneered” surface. of course any heavy tear out would telegraph in the modern thinner veneer. So I suspect only a scraping plane would be your choice.
Thanks again
Joe
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If we’re still talking about preparing groundwork for veneering, then a toothed scraper blade is my sole recommendation.
Taming cranky grain is another kettle of fish – for which I would usually reach for a ‘Billy Bob’, but as you indicate, sometimes even that isn’t up to the task and a scraper plane is called for.
JP
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I thought it might be useful to update this post: Lee Valley now offers 17 tpi and 25 tpi toothed blades for their bevel-up smoothers, small smoothers and low angle jack planes.
http://www.leevalley.com/en/wood/page.aspx?p=72096&cat=1,230,41182,43698
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