Something Might Have Gone Wrong

Ugh. Here is how something goes really wrong. This is supposed to be a simple shelf, and early on it got contaminated. Ever since then I've been struggling to seal it, or get the contamination out, or both. In the end I was forced to drench the piece in shellac, and then started topcoating with a waterbase (from a company whom I won't name, but the products tend to piss me off). I never got the nice finish I wanted, so had to sand down again and the thin areas of the finish became partially exposed, so back to shellac. This is the underside, so I pretty much left it at this.

I sanded the other side down to bare wood and began to lacquer it. Generally you do not want two different types of finish on either side since that will give differential absorbtion of humidity which results in warping. On this piece when I sanded it down, because it's purpleheart, I had to expose it to sunlight to restore the color. This caused a differential change in humidity... it dried out, and created a severe cupping. Before going ahead and sanding down the underside completely, I decided to expose it to sunlight to see if I could restore it.

Well either water or some solvents that had not completely boiled off decided to go gaseous under the sunlight much faster and in greater quantity than I had thought. After a morning, the bubbles on the right hand side are what happened.

I'm also wondering if it's actually solvent from the lacquer from the other side, which is a week old, that has been sitting deep in the wood. Purpleheart is very porous, so it would not be much of a problem for a solvent to travel right through a thick piece of wood like this.

Anyway, chalking this one up to major defeat.

Bookshelves in Blood and Steel

This is my current project, and is facing some major challenges, and is skirting the edge of miserable failure. The material is Bloodwood and I was able to find a really beautiful piece to work with. Unfortunately, since cutting it the material has twisted significantly. The original design for the bookshelf was to run four vertical bars through it and use flanges to trap the shelves in place. Since the material twisted, and cupped a bit, there is no way in hell this is going to work, and besides aligning and drilling the holes would be a nightmare.

Enter my brother into the fray. I'm lucky that he happens to have a machine shop. So I altered the design and am using 1.5" round steel stock, and the results I think are better than the original design. I wanted it to feel very open instead of being Just Another Box With Shelves In It. The wood I have is incredibly beautiful, and I wanted to free it up as much as possible to breathe. I will make bookends most likely, or maybe try for some riverbed rocks to use as bookends.

The hope with this new design is that with the pieces bolted down to heavy duty steel, the twist won't be a problem anymore. Once wood has twisted, usually the advice is to throw it out. Cupping can often be fixed, but twisting is something that is in the layout of the fibers of the wood. This wood, when bought, had been cut and was supposed to have been dried properly. However, because of how it was stored, the weight of other wood on top of it probably prevented the twist from coming out. After it was cut and planed, the twist showed up. I can see why it did, the grain pattern is not even, which makes for a spectacular piece of wood but opens me up to this kind of issue. I'll hope that the steel and the weight of the books deals with the problem.

So far the shelves have taken on Tung Oil, and I am beginning to Lacquer them now. I'll let the Lacquer cure out, then will get the holes drilled for mounting, before rubbing out the Lacquer flat for the final finish.

By the way, the Sagulator is an indispensable calculator for anyone who is building wood shelves. It will let you know if your design is going to fail miserably or not.

Japanese Inspired Coffee Table

This was my first big furniture project. Having some computer skills comes in handy, as I am able to model my ideas out in Rhino before cutting wood. It allows me to make sure I have the feeling I want from the piece and know what I am getting into. I model all of the cuts and joints as well, and I try to design for simplicity in construction since I have limited access to tools.

This was my first experience with Bloodwood, and how I learned the hard way not to use Shellac directly on Bloodwood. One thing I strive for is to work with the natural colors of the wood, I am not a big fan of staining or obscuring the wood in any way. In order to provide a nice contrast with the Bloodwood, I chose Wenge which is a favorite wood of mine. The colors go beautifully, and it makes for an unusual looking table. Besides the bold stripe down the middle, I added some accents in the apron that seamlessly appear out of the legs. Overall I am very pleased with the design... I don't like frilly or overly fancy things: first, they're hard to make, and second, I think they look stupid. I aim for clean, modern looks as this suits my aesthetic tastes and also, I can make them.

The trickiest part of this design was the joints of apron and legs. The legs are assembled from four pieces of 0.5 x 3 x 12 inch pieces of Wenge. The edges are cut with the table saw to 45 degrees, then they are assembled into the blocky legs. There is a nice trick to this, you lay the pieces out side by side with the joint surfaces face down on a table, then duct tape down the edges where they line up. This lets you flip them over as a unit, run glue down the joints, then roll them up and tape the final edge. The tape prevents the glue from spilling to the outside surface, and holds the pieces square. It's a nice, and cheap method if you don't have fancy pants clamps to hold them in place.

Once the legs are cut, I made some square caps on the table saw and cut a bevel in with the router, then ran them upside down on the table saw to cut the slots where the apron would come together. I then drilled and chiseled out the slots. The bloodwood highlights were added to the short crossmembers of the apron with a lap joint, and a gooseneck. I was worried about strength in case the tabletop warped so tried to design the joint to resist the upward pressure well. The angles on the apron ends represent a 30 degree right angle triangle which has a nice feeling to it.

The tabletop panels use a lap joint, I don't have any equipment to make anything more fancy than this and it seems fine so far. Another trick when gluing together long panels like this is to run tape all along the seams of the join (the photo is of another similar table I built afterwards). When you clamp it all together, any glue squeezeout ends up on the tape. There are no worries then about glue cleanup, just pull the tape off when you're done.

The table assembles pretty simply, though there was some painful hand-tuning of the intersection of the apron with the legs. Because everything is hand-sanded, the apron would vary in thickness by a millimeter or so and that caused a lot of unhappy times. After shellacing though, the results I thought were very beautiful.

This project suffered badly from sandpaper contamination, so I had to redo the finish a few times (the pain). Nothing would stick. Furthermore I had really soaked the Wenge with Tung Oil, so much so that there was little chance of it ever properly curing out. That gave me many, many days of re-sanding and re-attempting to put a finish on. Very sad and tedious, and could have been avoided by (a) being sparing with the Tung Oil, there is no need to flood, and (b) making sure to clean all sanding dust. Failure to do so can prevent the finish from adhering. See my on Sandpaper Contamination.

Relative Merits of Finishes

Finishing is a real art, and each of the types of finish has relative merits. Some are harder to apply, some are easier. At some point I'll walk through my approaches for what they are worth. For the beginner though, some guidance can be had here I think.

Your basic finish types are reactive vs. evaporative. Reactive finishes form one-way chemical bonds that will not break when their solvent is re-applied. Evaporative finishes will re-dissolve in their solvent. There is a third type, Coalescing finishes, which are typically waterborne and feature some evaporating and some reacting.

The main reactive finishes one will encounter as a beginner poking around through Home Depot or someplace similar are: Tung Oil, Linseed Oil, Danish Oil, Polyurethane and other Varnishes. Note that Waterborne Polyurethane or "Crystal Clear" Polyurethane is a Coalescing finish, covered later.

Tung Oil and Linseed Oil need only to be applied sparingly, unless being wet sanded for pore filling. Their purpose is mainly to impart color and depth to the wood. Linseed Oil on its own may never dry, so the version people should buy is "Boiled" Linseed Oil (this contains catalysts that speed the drying up to about 24 hours). Both Tung and Linseed react with oxygen in the air and change to a solid... this is not drying like an evaporative finish, but it is a one-way reaction. They are easy to apply: dip a rag, and wipe on sparingly. No errors, no problems. Not very durable, and little resistance to anything. They can impart a darker, more dramatic color and figure than a varnish will alone, and varnishes can be applied over oil.

Polyurethane and Varnishes also chemically react with the air and are a mix of one of the above oils, and a resin. Drying takes a couple of hours (the solvent boils off), curing for full hardness can take a week (bonds between the molecules form). They are difficult to work in general, the manufacturers have to ship them minimally thinned so that only a pro could apply it due to EPA regulations. Even if you thin them out, you get problems like runs, sags, dust, brush marks, dried varnish flakes, pools... you name it. These can be dealt with, it's a subject for a new posting though. Overall, difficult to apply, but very durable and resistant to spills. They are difficult to repair. Polyurethane is technically a Varnish but is usually spoken about on its own. Polyurethane in particular breaks down in UV light, so if using outdoors, you absolutely must buy an outdoors version which will have UV blockers in it.

Danish Oil is basically a long oil varnish. It has very little resin in, so applies easily like an oil, and features more resistance than an oil finish would have due to the resin. It's a great choice for the beginner provided the piece is not going to get a lot of wear. You can get very beautiful results. I like the Deft danish oil product.

The Evaporative finishes that one will usually see are Lacquer (Nitrocellulose) and Shellac (a resin secreted by the Lac beetle). Because these finishes can re-dissolve in their solvents, they can be repaired easily. Both of these finishes impart very dramatic effects and are very clear. They both dry very quickly, Shellac can dry in seconds. Overall they work in a way that offers much fewer surprises and "wtf" moments than Poly and Varnish offer. Shellac is more difficult to work with because of its rapid dry time, but otherwise the two are very similar.

Lacquer ships dissolved in a real witches brew of solvents... if these solvents come in contact with any of the other finishes usually a big mess is the result. Of them all, this is the one that you do NOT want to get on your skin. Lacquer is more durable than Shellac, but both can be hard to apply and get good results. Best results are usually considered to be had by spraying. Watco though makes a brushing Lacquer that I am very happy with, for me it flows out much nicer than Deft's product, and it leaves little to no brushmarks and bubbles are a non-issue. Lacquer is generally considered the best all-around finish when weighing out the pros and cons. Because of the witches brew of solvents, Lacquer dries to touch quickly but has a time where it is almost the consistency of a gel for an hour or two... after this, depending on how thick and how rapidly you put it on, it make take a week or more for all of the solvent to completely evaporate off. This for Lacquer is the cure time, where final hardness is achieved.

Shellac on the other hand is only dissolved in alcohol. This can really dry your hands out if you stay in prolonged contact (and be painful), but if you spill some on yourself it is no big deal. Best results for the amateur with Shellac are usually from padding. For this, you dilute some Shellac using a squeeze bottle and alcohol, dampen a pad with it, and rub on quickly. It will dry seconds after your pad is gone, so there is a need for a light and quick touch here. When properly applied, Shellac is probably the best looking of all the finishes. To apply it properly though, is an art for in and of itself. Shellac will also cure under the same principles as Lacquer.

The Coalescing finishes are those that are waterborne. They will say somewhere on the can that they should be cleaned up with soap and water (which is a nice feature), they have much less solvent (another nice feature), and many of them are completely colorless, which may or may not be a nice feature depending on what you want. These finishes work by suspending particles of solvent bonded to resin in a bath of water. When the water evaporates, the solvent activates and the resin particles become bonded together. The bonds are not as strong in general as those formed by polyurethane, but this technology is constantly improving and will probably be the way of the future.

The main downsides of these finishes are that they are extremely difficult to apply in any way other than spraying, they don't level very well and they can easily foam and bubbles can get locked in because they dry so fast. Furthermore, most of them look cold, and cheap compared to any of the above finishes. Manufacturers are desperate to advance these technologies and convert users of traditional finishes, so (in my opinion) make a lot of Big Claims that do not bear out in practice. The hardnesses of these finishes are exaggerated ("diamond hard"), the ease of application is exaggerated ("formulated specifically for brushing and padding" says one manufacturer... except, not.).

The one thing that generally holds true is that they do clean up very easily and tools are easily reused. Sometimes the uneven leveling common to these finishes will clear up overnight as slower reactions in the solvent take over from the initial evaporation of the water. I've found that the best waterborne finish out there is the common Varathane. All of the higher end "premium" waterborne finishes that I've tried have not met up to the claims that the manufacturers have made, and none of them settled out as flat as Varathane has (in some cases, perfectly flat). So, sprayed on Varathane from the can is actually a decent choice for a beginner or DIY-er. Note that the "Professional" Varathane is an oil-based finish, not the waterborne I'm speaking about here. In general these will be more durable than Shellac and Lacquer, but less durable than Varnish.

So for the beginner, the best two finishes to use would be Deft's Danish Oil, and a spray can of Varathane (not on the same project!). Both of those are very hard to screw up if you follow the directions and both will give very different looks and durability. From here, move to Lacquer at medium skill, and then to Varnish or Shellac at high levels of skill.

The only finishes you should not worry about a solvent mask are Shellac, and Tung or Linseed Oil. Everything else has a bad solvent, even waterborne, don't breathe it and apply in a well ventilated environment.

I'll write more one day on what I do to apply each of these. Finishing is usually a struggle, but with some perseverance, good results can be had.

Finishing Bloodwood

The tables below are made with center strips that feature Bloodwood, which is a gorgeous crimson color with orange and yellow highlights. Like Purpleheart, it features chatoyancy and the associated play of color with a changing orientation towards the light source.

Like Purpleheart, this wood has some caveats for finishing. As waterborne finishes make a mess of Purpleheart, Shellac makes a mess of Bloodwood. The reason for this is that the colorant in Bloodwood is rapidly brought into solution by alcohol, which is the solvent for Shellac. Alcohol and water are both polar solvents, unlike mineral spirits, turpentine, etc., which are used as solvents for oil based varnishes. When building with Bloodwood, this aspect of the finish has to be taken into account. Any attempts to pad or french polish on shellac is going to fill the pad with Bloodwood dye and bring red color elsewhere into your project.

Furthermore, the movement of the dye is likely to reduce the overall contrast in the appearance of the Bloodwood.

It is possible to spray on waterborne finishes onto Bloodwood, and in this case, I would recommend spraying them on very lightly to begin with so that they dry almost immediately (waterborne tends to dry fast anyway). Build up the first couple of coats very slowly in this manner until a barrier is formed over the wood.

If a "colorless" waterborne finish is used (the manufacturers will often say "water clear" or "crystal clear" to denote these finishes), the effect on Bloodwood can be quite striking. After the application of a blonde shellac or any oil based finish, Bloodwood takes on a color similar to the tones one sees in fire. By going for a crystal clear waterborne finish, the wood is left with a very pure and striking red tone. Varathane in fact appears somewhat bluish, and this can even be topcoated with Shellac in the case of a piece like my tables here (the Purpleheart would be taped off to protect it from the Varathane seal coat).

Otherwise, striking finishes can be had with any of the standard finish types when applied to Bloodwood.

I Hate Pore Filling

However, it's pretty essential if you want to go for a glassy piano like surface. High gloss brings out the most color and depth in wood. This is because a satin or semi-gloss surface achives its affect by scattering light back to the viewer's eye, and this scattered white light creates the whitish glow on these finishes, and it's that whitish glow that obscures detail (including flaws!) and reduces contrast, making colors seem more dull.

When working with wood that features chatoyancy, where the play of light on the fibers of the wood creates different colors when changing the angle of view towards the light, the best finish to maximize this effect is going to be a flat as flat, glossy finish.

One finish I have used often lately starts with a mix of 75% tung oil and 25% polyurethane, thinned with mineral spirits. This is applied like a danish oil, flooded, and rubbed in for 15 minutes, then dried off by hand until the surface is clear of any oil. This is then left a day to dry.

On the third coat, I use wet/dry sandpaper and sand the wood. The slurry of tung, polyurethane, and wood dust has a lot of body, and when wiping this coat dry, wipe at 45 degrees or 90 degrees to the grain of the wood. This will leave a lot of the slurry in the pores, filling them up after a session or two. The wood here is Purpleheart and it has very large pores. This is the fourth coat of the tung/poly mix. It takes a few days to get this done, but the eventual results are worth it.

I build some middle coats once the pores are filled with a mixture of 5:1:5 poly:tung:mineral spirits, this is a wiping varnish. The final coats finish up with a 2:1:1 poly:mineral spirits:naptha wiping varnish. The naptha blows off quickly and is only there to ease application. I don't want this too lacking in body because runs and sags can develop when wiping on. The mineral spirits stays to help with leveling and bubbles for a longer period than the naptha does.

The final finish following this schedule is quite dramatic. Here are a some pictures of two tables I built previously and completed with this finish.

Sandpaper Contamination

Non-Stearated Sandpaper. Important words.

I recently spent a lot of time trying to fix problems that I had no idea I was giving myself by not thoroughly cleaning off sanding dust from hand-sanding with Norton 3X stearated sandpaper.

Sandpaper normally clogs up, moreso if you are sanding a finish. Ways around that include wet sanding, or using stearated sandpaper which self-lubricates and resists clogging. The result is faster results that are more uniform than you would get otherwise. Norton, bless them, claims that their sandpaper is compatible with all finishes but my own experience says otherwise.

Once contaminated and poorly cleaned, shellac will form tiny pellets and a rough surface, while polyurethane will pull away from the contaminated areas. If poured on, shellac will fisheye as will lacquer. After laying down shellac thick, I've been able to come back with my thumbnail and run it along the finish, peeling it off with medium pressure.

It's possible to seal these contaminations in by repeatedly coating it over. The coats adhere very slightly and build somewhat horizontally to finally cover over the contamination, but it's best to just avoid this entirely. With polyurethane or varnish, when rubbing out, you can give yourself a real headache by burning through... since the contaminated areas are difficult to close up they tend to be easier to burn into since they may have a thinner set of layers of finish on top. And then once burned open the difficulty of closing them up raises its ugly head again.

The solution if you think you have a sandpaper contamination problem after you've started finishing, is to sand down the affected area, then wash it first with water, then with a 50/50 or 100% methyl alcohol wash. I've stuck pieces under running water and rubbed them.

The alcohol will help dry out the water, and then leave the piece overnight to be sure it is thoroughly dry before attempting to continue your finishing project.