Finishing end grain

Overview

End grain is the cut ends of the wood's tubes, and it behaves like a bundle of straws. The USDA Forest Products Laboratory's Wood Handbook says the end grain of wood is commonly 100 times more porous than the side, so it absorbs much more stain or other finish. Two things follow: stained end grain turns much darker than the faces, and, for water, the Wood Handbook says liquid water enters wood 10 to 100 times faster through end grain than through the other faces, which is why sealing it is called critical outdoors (Outdoor finishing).

When to use

• On any stained piece with exposed end grain: tabletop ends, breadboard ends, the exposed end grain at the top and bottom of raised panels, and turnings and carvings (Southwick: turning or carving wood also exposes end grain that can cause distracting discoloration).
• On everything you finish with a film. The Wood Handbook notes that a film-forming finish applied to all sides, including the end grain, will likely slow moisture change in the wood; see Wood moisture and acclimation before finishing.

Materials and tools

Sandpaper; a washcoat (Pre-stain conditioner and washcoat) or straight clear gel varnish; a brush or rag (Gel stain, Oil-based pigment stain).

Steps

1. Sand the end grain more. Popular Woodworking's cabinet-grade guide says darkened end grain is primarily the result of inadequate sanding. Sand it more thoroughly than the faces (Sanding schedule).
2. Seal it before staining. Target a washcoat just to the end grain with a rag or brush (cabinet-grade guide). Southwick's method for a tabletop: apply straight clear gel varnish to the end grain only and then immediately apply any oil-based stain, which also matches the end colour to the surface and shows the end grain's figure.
3. Do the same for raised-panel end grain and turned parts (Southwick).
4. Check often. Southwick (on pine) notes it is tough to get uniform penetration on end grain, and says to wipe it occasionally during staining to check its appearance, and to experiment on end grain, face grain and veneered stock.
5. Finish the ends with the same coats as the faces. The cabinet-grade guide finishes door edges fully; see Wipe-on application and Spraying with HVLP.
6. For outdoor work, the Wood Handbook says to seal all end grain, before assembly where you can: it is often impossible to reach afterwards. Where it cannot be reached after construction, it recommends flooding it with a water-repellent preservative.

Common problems

• Ends much darker than faces. Mostly inadequate sanding (cabinet-grade guide), plus no sealer. Fix both before staining.
• Ends look blotchy on softwood. Pine end grain is hard to colour evenly (Southwick). A washcoat evens it (Eastern white pine).
• Open vessels leave low spots. The Wood Handbook says vessels let a lot of finish flow in, leaving thin, low spots in film finishes; fill the pores first for a flat film (Grain filler (pore filler)).

Safety and environment

Oil-based stains and gel varnish rags can ignite spontaneously: see Oily rag safety. Fine sanding dust of end grain is hazardous like any wood dust.

Related

• Pre-stain conditioner and washcoat, Gel stain, Grain filler (pore filler), Sanding schedule
• Finishing sheet goods (plywood, MDF, MDO) where plywood and MDF edges behave like end grain
• Outdoor finishing, Wood moisture and acclimation before finishing