Reply To: Is it best to stain your pieces before assembly or after?
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The guy that taught me finishing gave the exceptionally clear advise of, “it depends.” You need to think through the details of your piece and your finish and decide. First, you need to distinguish between dye and stain. Stain has both pigment (color) and binder. Stain is like color plus top coat mixed together. With a dye, you can apply coat after coat and each will be darker because there’s no finish to seal the wood against the pigment. Stain, on the other hand, seals the wood, at least in part, on the first coat and then successively more on each subsequent coat. Thus, additional coats only darken the color slightly. This is why your drips and runs are so visible with the dye. Note that both dyes and stains can blotch. That’s a separate story.
Dyes can often be adjusted after application. A rag wetted with the dye solvent will often be able to take dye back out of the application. At times, this allows you to adjust dark spots and feather the work together. Other times, it makes a mess. A rag wetted with dye or dye plus the dye solvent can be used to feather things together…or can make a mess.
Generally, I will apply color and finish after assembly, but I will adjust the construction to suit finishing. Drawer bottoms and cabinet bottoms will be removable, if possible, to give better access. If I have a panel (frame and panel), I’d rather get color on it before gluing up because, at least around the bevel, because, if it shrinks later, it shows a line. If it gets dinged up, I can adjust/repair.
I’m not sure if your dye was really a colored shellac or if it was an alcohol based dye. Alcohol based dyes are harder to work with than water based dyes because they dry so much faster. The trick with water based dyes that I was taught was to spray the dye in a light, dry coat working rapidly to get dye uniformly everywhere without runs and then open up and really get things wet. Finally, wipe it back. The idea is to not risk any runs (which are like double coats) to occur until there was enough dye everywhere to control. I think what’s really happening is that the first go-over gets things wet but without runs, which slows down the effect of the heavy run that may occur as you get things really wet and gives you time to wipe things back. Darkness is controlled by diluting the original dye. If you cannot spray, you can use the same general idea by making sure to not allow runs first, working up to a wet coat, and then wiping back. Clearly this is a mixture of magic and practice. I’m still not comfortable with dyes by hand and always hold my breath. I have a wet rag ready to wipe back dark spots and I use water based dye. Now for the real secret: I wipe my piece down with water before I apply the dye. This reduces how fast the dye can be absorbed. It can help with reducing blotching. But, be aware that it also reduces how dark the finish will be. It’s dye, though, so you can put on another coat.
This shows how to help think about assemble vs. not assemble and, just as important, the order in which to do various parts of the work. If I’m doing a table, I clearly do *not* want the top to be attached. The top would be in my way and would lead to runs down onto the apron. If there is a shelf, I want it to be removable, if possible. If there is a door, I want the door to be off. If there is a drawer, I want to finish it as a separate component, bottom out. When I do a top, I decide whether I want dye on the show face first or last.
Some things are hard to cope with, like Craftsman style, because of all of narrow gaps that can be present. This may affect how you choose to finish. If you have oak, as is common for Craftsman, blotching isn’t an issue. I might choose stain in this case because it has fewer issues than dyes for runs. On the other hand, I really like dyes, so maybe not. But, I’d have a plan for how to deal with all those nooks and crannies.
By the way, yes, finish can keep glue from working. Tape off joints if you decide to apply anything ahead of glue up. If you are using a true dye, it is less of an issue, but still tape first. General Finishes brand dye (my current favorite) seems not to be a pure dye and has some binder, so you never know. So, tape it. With stain, definitely tape it. To date, though, I’ve not finished anything prior to glue up. The day will, though.
You need to think through this all over again for the top coat. Shellac is nice because it is so workable. Miss a spot? No biggie. Catch it on the next coat. You can use a brush or a fad and get into any place you want. Water based finish or polyurethanes? Well, they don’t melt into the last coat. I like them, but getting into tight places, like on Craftsman, can be tricky. Since I have spray equipment, I’d likely brush into the tight places (and everywhere) with light fist coat(s), and then spray the final coat. On the final coat, I’d not worry about getting into the nooks and crannies. I will only spray non-combustible finishes, which pretty much means only water based.
There’s another reason to color before assembly. My instructor’s work often looks like a vandal has hit it with random bits of pale dye. A bit here, a bit there. This is during construction and dry assembly. I asked why and was told, “So the grain doesn’t fool me.” He uses figured woods. Chatoyance leads to wood looking very different from different angles and sometimes you cannot see the effect until the color is on. This is a big problem in book matching and is why bookmatched, figured wood can look very light on one side and dark on the other. So, he uses diluted, pale dye to decide the orientation of his material during construction. He then sands / scrapes it all off before real finishing and sometimes before glue up.
One thing to keep in mind is that dyes give a problem that stains do not. Since there’s no binder, you can take the color back up with solvent (water, alcohol, etc., according to the particular dye). This means that your finish coat can pull up the color and that the dye can migrate up into your finish. I know from experience that the General Finishes oil and water based finishes can be used together and with their dyes, if done properly and if allowed to dry. Thus, what I will do is to apply the GF water based dye, let it dry, and then hand wipe a coat or more of GF oil based finish such as Arm-R-Seal. The Arm-R-Seal is not water based and will not lift the dye. Once the A-R-Seal is dry, I can now go back to water based finish or shellac without worrying about lifting the dye or having a finish run turn into a little river of dye. The other thing I can do is use that barrier coat as a substrate. If my dye isn’t uniform, or if I want to tint it, I can put GF dye on top of the Arm-R-Seal. It won’t be a big color change, but I can even things out and tint a bit. This is the real meaning of “build a finish.” Build a finish doesn’t mean “build up,” it means you adjust and tune as you go, just like joinery. The first layers don’t need to be perfect. I’m confident you can address your runs.
…Sorry this ended up being a book.