By Ken Evans
Even though painting is one skill and staining wood is another, most painters still get asked to finish staingrade trim, wainscoting and wood interiors. Who else but painters are clients supposed to ask to tackle this kind of work? And whether you’re comfortable with stain or not, there’s money to be made and reputations to be built getting good with this kind of wood.
Traditionally speaking, stain-grade finishes colour the wood in the first step, then coat it under urethane or some other kind of sealer for protection in another. But to keep things simple, I’ll call any transparent, interior wood finish “stain-grade” – whether or not it includes a step to change wood colour or not. Most of the process is the same, and all transparent wood finishes start with the same, crucial step.
Start With Sanding
Even million dollar homes I visit frequently suffer from inferior stain-grade finishing. It’s a shame, and while lack of sanding is the most common reason why, it’s easy to see where the trouble comes from. Sanding wood is a pain, especially when that wood is trim around a door or window and it’s been milled to an intricate profile. Pain or not, excellence demands that all new wood be sanded before any transparent finish goes on. This means every inch of trim and every visible piece of flat stock. That’s because even seemingly smooth wood has subtle marks left behind by the milling equipment that shaped it. Invisible at first, these mill marks show up quite noticeably after the first coat of stain goes on. It’s ugly.
Even million dollar homes I visit frequently suffer from inferior stain-grade finishing.
How to succeed with stain-grade finishes on wood
If you’re lucky enough to be finishing flat woodwork, start with a belt sander spinning an 80- or 100-girt abrasive, followed by a half-sheet inline sander with 120- or 150-grit paper, finishing up with a quarter-sheet finishing sander and 180 or 220-grit sand paper. All this said, as a painteryou won’t often enjoy situations where sanding flat, horizontal surfaces are so convenient. More than likely, most of your stain-grade work will involve profiled trim and moulding. It may even already be mounted on a wall, and this is where a trick comes in.
A Canadian power tool accessory called a sanding mop (877-287-5017; (www.stockroomsupply.com) is unique among sanding tools because it makes it so fast and easy to sand curve shapes and molded profiles. The sanding mop is made of cloth-backed sandpaper mounted on a mandrel that spins in a drill press or hand-held drill. All those spinning layers allow curved and intricate surfaces to be power sanded to remove mill marks, all without rounding off any crisp details – even fine ones. You wouldn’t think this thing would work, but it does. Sanding mops can be used in a hand-held drill for already-mounted trim, or in a drill press for sanding trim before installation. Check out my video and see for yourself: goo.gl/Qge1y0
Finishing Option #1 Stain-Free and Sealed
This is for clients who want natural wood colour and grain to show through with no added colour, and it’s the simplest stain-grade option going. The easiest product to brush on in the field is urethane, but you need to choose up front between waterbased and oil-based.
All else being equal, oil-based urethanes are easier to succeed with than waterbased because they dry more slowly, allowing brush marks to flow out. On the downside, governments everywhere are restricting the sale of oilbased urethanes for air quality reasons. That’s why they’re getting rare on store shelves. Oil-based formulations also usually impart a yellowish colour to the wood – a great thing for some clients and situations, and a bad thing for others. Always use waterbased urethane when clients want the whitest and lightest results on pine, maple, eastern white cedar or other light coloured woods.
Waterbased urethanes are almost always quick drying (too quick in my book), so you can only brush a given area once. Get this wrong and you’ll create visible brush strokes and hardened bubbles. Not good. You’ll get better results adding a retarder to waterbased urethanes to slow them down and allow some flow-out.
Regardless of how thoroughly you sand before urethane application, your wood will be quite a bit rougher after that first coat dries. That’s because all types of urethane – both oil- and waterbased – cause surface fibers to swell, stand upright, then harden in the upright position. The surface won’t look much different to the eye, but the wood will feel like it’s got a bad case of 5 o’clock shadow. This is normal and it’s why sanding lightly with fine sandpaper before the next coat is vital.
I use 220- or 240- grit open coat sandpaper in a quarter-sheet finishing sander for flat areas, and a 3M rubbing pad or Siawool for profiles and rounds. This synthetic steel wool substitute works exceptionally well where regular steel wool would leave residue behind that would rust in the presence of waterbased urethane.
Finishing Option #2 Stain and Sealed
Staining traditionally happens first, as a separate step before sealing, because this approach creates the greatest clarity of grain. Both liquid and gel stains go on in the same way, but liquid stains benefit most from a trick I’ve learned. Daubing liquid stain onto the wood with a brush every 4” to 6” then rubbing it out with a rag is better in two ways than rubbing stain on directly with a rag. First, it’s easier to put on just the right amount of stain by daubing. And second, a brush lets you apply stain into nooks and crannies of molded profiles much more thoroughly than with a rag.
Always rub the daubs of stain evenly into the wood with a rag, working parallel to the grain only. Most stains these days are still oil-based, and you can safely coat them with either oil- based or waterbased urethane when they’re fully dry. Waterbased stains can also be sealed with oil-based urethane after a day or two of drying time. Check out my video to see the waterbased staining process in action: googl/1K2NGK
A versatile painter is a busy painter, and since clients usually turn to painters for help finishing transparent wood, why not take on the work? Even if it doesn’t involve paint, it’s usually worthwhile just the same.
Although you can certainly apply a combination of stain and urethane to any kind of wood, a problem emerges when you’re dealing with high-wear surfaces like stairs, railings and wooden countertop edges. Traditional staining and sealing looks great at first, but when the urethane layer wears out, followed by the stain layer, you’ve got ugly light wood exposed and two problems. Besides looking terrible, it’s impossible to renew that worn finish seamlessly without stripping back to bare wood and starting from scratch. Lack of repairability is the problem, and this is where coloured oil finishes make all the difference.
Polymerized tung oil is excellent for sealing bare wood without adding colour, but when I need to darken and protect high-wear wood, my favourite option is oilbased, coloured finishing oils. I find that dark walnut shades are especially good at imparting a rich, dark hue, even on hardwoods that aren’t particularly absorbent. I finished an ash staircase in 2009, for example, and the treads and handrails are still as dark and even as black walnut today.