Bodybuilding With Wiping Varnish: All The Instructions You Won’t Find On The LabelComments (0)
This article is from Issue 63 of Woodcraft Magazine.
All the instructions you won’t find on the label
Wiping varnish is one of the most popular finishes available to the small shop woodworker, and for good reason. It’s easy to use, attractive, and versatile, allowing you to create any sort of build that you like. For example, you can wipe on a series of light coats, buffing off the excess between each one to create a thin “in the wood” look, which is fine for decorative items that won’t suffer abuse. On the other hand, you can build it up pretty much as thick as you like for tough, durable protection on tables, chairs, and other furniture that sees a lot of use.
However, building up a truly protective coating with wiping varnish requires a lot more finesse than the relatively simple “wipe-on, buff-off” approach appropriate for a thin decorative finish. Unfortunately, the product label only has room for the basic instructions, often leading to a lot of head-scratching and disappointing results. Here, I’ll walk you through a process that yields a beautifully lustrous finish that scoffs at liquids and abrasion, and begs to be touched.
The 4-Day Schedule
Day 1: Brush on a thinned coat, let it soak in, and then wipe off the excess.
Day 2: Wet-sand with 400-grit wet/dry paper lubricated with mineral spirits. Then wipe on the first full-strength coat.
Day 3: Wet-sand with 600-grit wet/dry paper. Then apply a second full-strength coat, and let it cure for at least 3 days.
Final Day: Rub out with 0000 steel wool. Then wipe on a thin coat and buff it off almost immediately. Let dry overnight, and you’re done.
To watch a short video featuring some of the moves in this story, visit woodcraftmagazine.com, and click on “Online Extras.”
What is “wiping varnish”?
Wiping varnish is basically a thinned version of brushing varnish that has been modified with a relatively small amount of oil (often tung oil). Because of its high-solids content, it dries hard and can be built up. This is in contrast to many oil and oil/varnish formulations that contain larger amounts of oil, and which result in a softer finish that won’t build well. Unfortunately, vague product labeling can make it difficult to distinguish between wiping varnish and softer oil-heavy formulations. To identify wiping varnish, apply a few drops to a piece of glass, and then let the finish dry for a day or two. If it then resists fingernail pressure without leaving an indent, it’s likely a wiping varnish.
There is a variety of good solvent-based wiping varnish products on the market, some of which are shown in Photo A. I’m partial to General Finishes’ Seal-A-Cell and Arm-R-Seal, but other brands can be applied in the same manner.
Preparing to finish
Sand the work through 220 grit, brush or blow away the dust, and then inspect the surfaces for flaws under a strong, raking light. Ensure that your shop environment is between 65-80°, with only moderate humidity. Cold impedes drying, and heat can accelerate it before the varnish has a chance to level properly.
Clean your finishing area, and don dust-free clothes. Set up a lamp for reflection, or work near a window with light banking off the workpiece toward your eyes. Prepare appropriate work supports, such as triangular sticks or screw boards. Finally, plan your finishing sequence to maximize accessibility and to ensure that the most visual surfaces are left for last.
Apply the first coat
The first coat serves as a sealer, so it needs to be thin enough to soak into the wood. This is where I use Seal-A-Cell, which has a watery viscosity compared to the more syrupy Arm-R-Seal topcoat. If you’re using a different product, you’ll need to thin it for the first coat. Just pour some into a jar, and thoroughly stir in enough mineral spirits to create a watery consistency that easily runs off your stir stick. For most products, add about 50%. For thicker formulations, such as Tried and True varnish, I add as much as 100%.
Flood the varnish on using a brush (Photo B), which works faster than a rag. Let the finish sit, reapplying it to any thirsty areas where it has soaked in. When it just starts to get tacky, thoroughly wipe off the excess with a clean, soft cotton rag. Then let the piece dry overnight.
Making a Rag Pad
Back-folding a rag creates a smooth face for applying varnish without leaving track marks. Simply fold the rag back onto itself several times, and then pinch it closed to create a smooth, slightly convex application surface.
Wet-sand the first coat
To prepare the surface for applying the second coat, wet-sand it with 400-grit wet/dry silicone carbide paper, lubricating it liberally with mineral spirits to keep it from clogging up (Photo C). For curved or narrow surfaces, use folded paper, dipping it frequently in spirits. For broader flat surfaces, wrap the paper around a soft backer. (I use a pliable foam block I cut from material sold as a kneeling pad for gardening.)
Your objective is to remove any dust nibs and minute hardened air bubbles, and to further smooth the wood. Feel free to sand fairly aggressively except on edges and corners, which should receive just enough pressure to knock down any coarseness. When you’re done, thoroughly wipe off the slurry of sanding dust and mineral spirits.
As an alternative to wet-sanding, you can rub the surfaces down with a synthetic non-woven abrasive pad, as shown in Photo A. In that case, work dry, using the least coarse pad that will smooth out any roughness. Afterward, wipe down the surfaces with mineral spirits to remove any dust.
Apply the second coat
Pour some well-stirred undiluted varnish into a dipping container, and then form a wiping pad from soft cotton cloth as shown in the sidebar (above). Dip the pad into your finish just deep enough to cover its face, as shown in Photo D.
Begin wiping the finish onto the work, moving swiftly and smoothly while applying just enough pressure to transfer the finish to the surface without wiping most of it away. I usually begin with the edges, following up with the faces. To avoid drips, don’t pull inward against corners and edges; always wipe along them or away from them.
On broad surfaces such as tabletops, work in long strokes, partially overlapping each previous swath. Rather than trying to begin a stroke at the very edge, swoop in a couple of inches away from it, and then pull the finish outward toward the edge to complete the swath. At joint intersections and other complex areas, form the pad to allow it to tuck into the spot, as shown in the Photo D inset.
This second coat will start to tack up much faster than the sealer coat did, so work small sections until you get a feel for the timing. While the varnish is still fluid in a dedicated area, use the pad to very lightly wipe over the entire section to even out the thickness of the coat. Then inspect it under reflected light to check for consistency. If all looks good, leave it alone; don’t re-wipe an area that has started to tack up because it will cause streaks. (If that happens, apply more finish to re-wet the surface and smooth it out.) When you’re done with the entire piece, let it dry overnight.
Wet-sand the second coat
Wet-sand the second coat (Photo E), as you did the first. However, this time you can use 600-grit paper, since this coat will probably be smoother than the sealer coat. Use 400-grit paper only if needed on particularly rough areas, and then revisit those areas with 600-grit. Thoroughly wipe off any residue with a clean, soft cloth.
Cover the surface thoroughly, using light pressure to transfer the varnish to the work, slightly overlapping previous swaths.
Apply the third coat
Wipe on another full-strength coat of varnish in the same manner as you did for the second coat (Photos F & G). Again, work in dedicated sections, thoroughly covering each area and then leveling off the fluid finish with very light pad strokes before moving on. Make sure to scrutinize the surface for imperfections under reflected light.
At this point, set the work aside for at least three days to let the finish cure hard enough for the final rub-out and topcoat.
Rub out the third coat with steel wool
At this point, you should have a sufficiently protective build of varnish on the work. It should feel fairly smooth, but look a bit too glossy. To smooth out any remaining dust nibs and take down the gloss, scrub the surface vigorously with 0000 steel wool (Photos H & I). Work in the direction of the grain wherever possible, and expect to get some exercise.
When the steel wool stops biting, refold it to expose a fresh cutting surface. Pay particular attention to edges and corners. When done, wipe all surfaces with a clean, dry cotton cloth, and then scrutinize them for a consistent luster under reflected light. Finally, run your fingers across the work. If any nibs remain, target them with dry 600-grit paper, applying only enough pressure to level them. Then re-scrub that area with steel wool.
Apply the final coat
Now for the crowning touch. Finishing up with a very thin “wipe-on, buff-off” final coat will fill in the steel wool scratches and bring the sheen back up enough to create the kind of beautifully lustrous finish shown on page 62.
Apply the coat as before, using a rag pad, but loaded with less finish this time (since most of it will be wiped away anyway). Apply just enough to cover the surface, wait a few minutes for it to start tacking up, and then use the application rag to vigorously buff off the excess (Photo J). Work at it until the rag doesn’t catch at all on the surface. Inspect everything under reflected light for any cloudy streaks that require additional buffing. After the piece dries overnight, it’s ready for service. Prepare for compliments.
You must be logged in to write a comment. Log In