Archive for the 'Finishing' Category

The wonders of shellac

Published on December 30, 2011 in Finishing. Closed

Shellac flakes

Shellac is one of my favorite finishes. It’s clean-smelling, quick and easy to apply, and rubs out beautifully to a gloss finish. It also has the virtue of hardening even over problem surfaces, such as the pitch pockets we sometimes find in cherry or pine.

Finishing Class students are often surprised to learn that shellac is an all-natural finish, and completely safe (if dissolved in food-safe alcohol). In fact, 90% of the shellac coming into the United States goes into the food and pharmaceutical industries, to give a gloss to fruits and vegetables, and to provide a time-delayed release coating on some medicines. People sometimes cringe when I tell them it’s an insect secretion (from the lac bugs of India and Thailand). These bugs suck the sap out of host trees and secrete shellac and wax which covers the tree branches. Under this coating, the insects mature. But if you like honey, you like insect secretions.

I just came across a company called shellac finishes.com which sells shellac flakes and has videos on the mysterious process of French polishing. It’s worth a look. Also worth a look is a video the owner made, showing how shellac is harvested and made into flakes. You can watch it here.

The final product

Published on February 9, 2011 in Finishing and Jigs and Fixtures. 2 Comments Tags: , , , .

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The "flag", laid out on an offcut from the turning

The last step was to make the “flag” that signifies an 8th note in musical notation. I actually didn’t care about the musical timing, but needed the flag to hang the note on its stand.

I bandsawed off a slice from that large bulge I originally turned on the bottom of the blank, drew the flag, then scribed a line on the right, where the tenon would begin. Scribing this way keeps the wood fibers from fraying at the cut line, giving a clean cut. I scribed both sides.

Cutting the tenon on the flag

I cut out the flag and tenon area on a scroll saw, then mounted the piece on a horizontal router table to cut the 1/8″ thick tenon. Here you see it elevated on a scrap, secured by clamps. A 1/2″ spiral straight router bit comes in from the right, held by the horizontal router. The router table allows me to set a depth of cut, then move the workpiece horizontally to cut one side of the tenon. The router is held on a plate attached to a 16TPI threaded rod. Once I’d cut one side of the tenon, I just turned the vertical control handle 10 turns, to raise the router by the diameter of the bit plus the 1/8″ thickness of the tenon.

With the tenon cut, I carved a slight flat around the mortise on the stem so the flag would sit flush, then glued it place. I sanded everything, applied three coats of shellac, then waxed and buffed the note.

The note on its stand

Finally, I brazed together some cold-rolled steel—1/8″ rod and 1/8″ x 1/2″ flat stock, into a musical “staff”. I attached the staff to a steel plate at the same angle the note hung at, sprayed everything with black lacquer, and the project was complete.

I’ll mention in passing how handy it is for woodworkers to have a bit of metalworking capability. Brazing is easy (like high-temperature soldering), strong, and can be done with a MAPP gas torch in your driveway. It let me make a light, strong stand in scale with the note—something harder to do with wood, which isn’t as strong in small sections.

Time for some alcohol

Published on December 23, 2010 in Finishing. 8 Comments Tags: .

Posting’s been slow of late—not because of alcohol, but from a combination of the usual holiday madness and the labors in launching a start-up company. But presents are wrapped, the PowerPoint file is saved, and I have a few minutes to tell about an interesting finishing solvent. (BTW, I’m just a satisfied user. I have no connection to the company.) I used this on the leaf plate mentioned in the last few posts.

White lightning shellac solvent

Tools for Working Wood’s wholesale division, Brooklyn Tool and Craft (BT&C), recently introduced a shellac solvent that’s 99.5% ethanol (drinking alcohol), with a little bit of rubber solvent as a denaturant.

So what, you say? Well, if you’re a fan of shellac finishes (as I am), you’ve probably used hardware store “denatured alcohol” to thin your shellac or dissolve the flakes; typically Kleen Strip’s S-L-X brand. However, BT&C’s product, while admittedly harder to find, has some advantages.

First, there’s safety. Read both Material Safety Data Sheets (MSDS). Of course ethanol has its hazards, but they’re more to do with inebriation than casual exposure. Observe the cautions on the label and MSDS, but it’s a pretty safe solvent. S-L-K’s Denatured Alcohol, on the other hand, is 50%–55% methanol, a more dangerous alcohol which can cause severe central nervous system reactions, according to its MSDS. BT&C’s shellac also has a flash point about 12 ºF higher than S-L-K’s, giving a little more explosion safety.

Second, there’s a usage advantage. I used BT&C’s alcohol to dilute shellac both for spraying and French polishing. Confirming what the manufacturer claims, my coats seemed to dry harder and faster than the same shellac thinned with the S-L-K product.

You won’t find this stuff in most hardware stores. However, it’s available on line at www.toolsforworkingwood.com, and also at Woodcraft stores. Give it a try and see what you think.

The end of the autumn (leaf, that is)

Published on November 23, 2010 in Finishing and Woodturning. Closed Tags: , .

Some of you’ve wondered if I went to sleep or moved away. It’s been days between posts. But actually I’m working with a little start-up, planning their marketing. And, like all new companies, it takes a lot of time. Plus, the holidays are starting to take their toll in tasks.

this spot of end grain created some finishing challenges.

Anyway… I sprayed several coats of amber shellac on the leaf plate, but the blotch in the photo, where a branch passed through the plane of the plate, absorbed finish unevenly. The result was a dull spot. Fortunately, since I used a shellac finish, the solution was ready at hand—French polish.

French polish was probably the first gloss finish, before the age of sandpaper. It’s achieved by applying lots (and lots) of super-thin coats of shellac to a piece. It’s very labor-intensive, so it’s rarely used anymore, but it’s a quick solution to problems such as this.

I put three cotton balls in the middle of a small, lint-free, cotton rag. I poured a little clear shellac into them, then twisted the rag tightly around them to make up a “rubber”. I took care that the bottom was smooth, without wrinkles. Then, I put a drop of oil on the bottom of the rubber, which was just damp with shellac.

Here’s the leaf plate wearing its final finish.

Now, using a motion like an airplane landing and taking off again, I “touched down” on the spot and glided off again, let it dry for a moment, then did it again and again (and a lot more). Each time, the spot got a little glossier. Finally, the sheen matched that of the surrounding area, and I could let things dry for several days.

Coming back to the piece once it was thoroughly dry, I did my favorite final rubout. I rubbed the piece with 0000 steel wool, using paste wax as a lubricant. I let the wax harden for half an hour or so, then buffed the surfaces to an even, satin sheen. Now the plate’s on the shelf, ready to be a Christmas gift.

The colors of autumn

Published on November 7, 2010 in Finishing. 9 Comments Tags: , .

Airbrushing with transparent acrylic paints.

Raw wood doesn’t look much like autumn, and I deliberately chose birch for this project to provide a neutral canvas. I’d previously dyed the wood with yellow water-based dye, and now it was time to add the subtle color gradations of falling leaves.

I wanted the grain and woodburning to show, so I chose transparent acrylic airbrush paints. I could build them up in layers to get the color effect I wanted, and an airbrush would let me place the colors precisely.

Airbrushing in process

I mixed each round of color, then diluted it 50% with airbrush diluting medium so I could build layers more slowly. I began spraying green around the edges of the leaf, overlaid with redder and browner tones toward the center. I used the original photo of the maple leaf to guide me, but tried to capture its feel rather than copy it slavishly (which I couldn’t have done). The photo shows the leaf partway through this process.

Amber shellac—the next stage

When I was done airbrushing the leaf had lots of color, but it looked a bit garish. It needed mellowing, and my favorite solution in situations such as this is amber shellac. I cut Zinsser’s amber shellac 50% with BT&C’s excellent anhydrous alcohol (more about this in a future post), then sprayed seven coats with the detail gun you see in the picture. The result was a deep, mellow amber cast that blended the airbrush colors and looked like autumn.

But the finish wasn’t done yet. That pesky knot with its uneven gloss will be dealt with next post.

Details, details

Published on October 29, 2010 in Finishing and Woodturning. 3 Comments Tags: , .

Burning veins into the leaf.

We recognize a leaf by more than its shape. There’s veining and color as well. Time to add those things.

I could see the veins clearly in the original photo, so I added them with pyrography—burning freehand sweeping curves into the wood with the skew-chisel-shaped handpiece you see in the photo. I kept the heat relatively low, about 4 on a scale of ten, so lines would stay narrow and sharp with minimal charring of the surrounding wood.

Coloring with water-based dye.

Coloring the leaf with water-based dye.

Once I was satisfied with the veining, I laid down an overall color wash using water-based dye. Since the background color of the leaf in the photo seemed to be yellow, I used W.D. Lockwood’s Canary Yellow dye. This is a water-soluble powder that I mix up and keep in concentrated form in squeeze bottles. Then, when I need some for a project such as this, I dilute the concentrate with distilled water. I like to keep the dye a bit weak, since I can always put on more coats to get a stronger color, but it’s a little harder to evenly remove too strong a color. In the photo, I’ve stained half the leaf so you can see the effect relative to bare wood.

Leaf with background color drying.

Water-based dyes raise the grain, so I lightly sanded with my final grit (#220) to cut off the whiskers between coats.

At left you can see the leaf as it looked on the drying mat when this stage was complete. The veins show nicely through the yellow dye. Note that the branch area, at about 2:30 in the picture, took the dye differently from the rest of the plate. This would also be an issue later, when time came to apply a finish.

Next, adding detail colors.

An autumn leaf plate

Published on October 22, 2010 in Finishing and Woodturning. Closed Tags: , .

A turned autumn leaf plate

Recently, a turning class student asked how to make sculptural turned plates, such as the (approx. 9″) plate at the left. The answer involves bowl turning, cutting, woodburning, and coloring—enough stuff to make it interesting. As it happens, I need to make something such as this for my turning club’s “seasonal” project next month. The next few posts will take us through the creation of such a plate.

The features of the plate are its shape and color. This means selecting a wood without distinctive grain so it won’t compete for attention.  I chose birch, a light and relatively soft wood that turns well, though it can fuzz up a bit.

The birch plate, ready for processing

The first step was to turn a plate—an open form with a shallow foot. This would give me the overall shape, and would allow the finished piece to actually hold something—candies or cookies, perhaps. I sanded all surfaces to #220. If you look closely at the picture on the left, you’ll see a tiny crack hear the rim at the 1PM position. I’ll have to plan my cutting around it.

The plate bottom, showing a small foot and the crack.

I need a “seasonal” theme. Around my home, leaves are turning from summer green to autumn flame, so a brightly-colored leaf seems perfect. A quick search through Google Images for a large “autumn leaf” yields lots of choices. I download a picture of a grape leaf with a shape I like, and print it out, above. This gives me a reference for color and vein position.

I open the leaf image in a drawing program (Adobe Illustrator, in this case), and have the software trace the leaf for me, so I can isolate it from its background. Then I can smooth and simplify the illustration to produce an outline I can use to cut out the leaf.

Next: cutting out the leaf shape.

Work by others

Published on September 19, 2010 in Finishing, Joinery and Others' work. 1 Comment Tags: , .

I’ve been busy this week; teaching classes two evenings, then at the Ornamental Turning Society meeting this weekend in San Jose, CA. Not much time in between.

Julien made this mahogany box as a gift to his wife for his 5th anniversary. Good move, Julien!

Occasionally I’ll feature work by others. Today I’d like to introduce Julien, a regular at The Sawdust Shop in Sunnyvale, and a student in some classes I’ve taught there. He’s becoming a fine woodworker and finding his voice in his craft as he builds his skills. He sent me pictures to share of a keepsake box he built for his wife to celebrate their 5th anniversary. He explains as follows.

“This box is African Mahogany, stained with a brown mahogany gel stain. The center piece of the lid is figured maple, dyed with a honey amber dye. The finish is shellac, wiped with a folded cotton cloth (no brush marks!) The frame uses splines, also made from African Mahogany, which you can barely see on the photos. All other joinery is just straight miters. I used blue tape for the glue up of the miter joints. The bottom is lined with black velvet.

Here's the inside of Julien's box, showing tight joints and a neatly mortised hinge.

The biggest challenge with this project was to sand the frame. I used
masking tape to prevent sanding marks across the grain. Unfortunately,
when I applied the stain, it revealed that I had not done enough sanding. At that point, I could have wiped off the stain, sanded some
more, and reapplied the stain later. However, with the anniversary date looming, and me wanting to move on to other projects, I decided the sanding marks would become a “unique” feature of that box. My wife never noticed, and I tried to hide those in the photo. The great equalizer (time) may help making those disappear.”

LESSONS

Julien used gel stain on the mahogany; a fine choice here, and even better on blotch-prone woods such as cherry and pine, because its thick texture minimizes the uneven absorption which causes blotching. He switched to dye stain for the figured maple panel, knowing that gel stain (or any pigment stain) would have suppressed all that lovely figure, while a dye stain (which amplifies differences in absorption) “pops” the maple’s grain.

He cites some trouble with sanding scratches, which a pigment stain tends to highlight (as its large pigment particles settle into surface scratches and pores). Several things help prevent these problems. One is to level joints with a hand plane or card scraper, rather than sandpaper, minimizing the heavy sanding. Skew the cutters at 45º, roughly following the joint line instead of the grain of either frame piece. The second is to make a sanding block with ends cut at 45º. That way it’s easier to see when you’re sanding right up to the joint. The last tip is to wipe the joint area with alcohol when you think you’re done, then hold the surface up to a glancing light. It’ll reveal scratches you might not otherwise see until you apply a finish.

Thanks, Julien, for sharing this project with all of us. We all learn together.

If you’re reading this and would like to send in a project with some commentary for this blog, please contact me.

Doorbell: Finishing up the feature panel

Published on August 23, 2010 in Finishing and Routing. Closed Tags: , .

Here's the feature panel, all inlaid and with the lines flushed to the surface, ready to finish.

I probably should have added these pics to the previous post. The first pic is of the panel after all the grooves have been cut and filled with cherry veneer slices. I leveled them and sanded the whole panel, then pre-finished it with shellac before adding the frame. I did this because the frame projects out a little from the surface of the panel, and it’s easier to rub out something that doesn’t have those little “walls” to stop your hand on each stroke.

Here's the panel wearing its mahogany frame.

The second picture shows the panel wearing its mahogany frame. The frame was moulded from flat stock with a router, using the same techniques as the larger mouldings I blogged about earlier. I masked the edges of the panel before gluing on the frame pieces, then finished them with shellac and rubbed them out to a satin finish with 0000 steel wool and wax.

Doorbell project: bleaching

Published on June 22, 2010 in Finishing. Closed Tags: .

Sometimes, wood’s almost the right color.

The highlight of this project is a panel that echoes the floor of the entry hall, where the doorbell lives. That floor is 20″ squares of sand-colored limestone with 1/4″ grout lines. So I planned to scale it down 90%, making a cross-hatch of 2″ squares separated by .025″ inlay stringing. With that in mind, I perused my on-line veneer sources.

I found the perfect stuff, a long sheet of quilted maple with billowy cloud figure. But when it arrived, it was much redder than it appeared in the vendor’s pictures. It didn’t go with the floor at all. It looked beautiful, though.

I thought about  returning it, but there’d be a couple weeks of delay, and no guarantee its replacement wouldn’t have the same problem. So I decided to bleach it, once I’d pressed it on an MDF panel. (I’ll talk about the vacuum veneering process in another post.)

I used Wood Kote's Lite-N-Up to bleach the red tone from this maple veneer, leaving it sand-colored.

Chlorine bleaches will remove dye colors, but don’t affect wood’s natural color. To get rid of the red tint I needed a two-part bleach, available at woodworking stores and on line. I used Wood Kote’s Lite-N-Up.

This product consists of two chemicals, hydrogen peroxide and sodium hydroxide. By themselves, neither does much to wood. But mixed together and brushed on, they form a powerful oxidizer that will remove the natural color from bare wood. An advantage of Lite-N-Up is that it is self neutralizing, so it doesn’t require a separate step later.

I brushed on a coat and let it dry, but decided it hadn’t removed quite enough color. So I gave it a second coat. In the picture you can see a piece of the original veneer on the left, and the bleached veneer (with a few coats of blond shellac on it) on the right. The red is gone, and it’s now a good match for the floor color.