Skip to content

Is it best to stain your pieces before assembly or after?

Welcome! Forums General Woodworking Discussions Finishing Is it best to stain your pieces before assembly or after?

Tagged: ,

Viewing 10 posts - 1 through 10 (of 10 total)
  • Author
    Posts
  • #548072
    Laci Nagy
    Participant

    Hi Folks,

    I just put together a small table and planned to finish it with oil (Liberon Finishing Oil). However, when I did some tests on the offcuts, it didn’t darken much and I needed to stain the work first. I ended up using an oil (methylated spirits) based dye.

    It was a pain to do once the table was assembled and I found some dark blotches where a stray drip sat longer than the rest of the stain. So for the next one in the pair, I thought I’d stain the pieces individually before they were assembled so that I don’t get any drips leaving darker patches here and there.

    So, my questions are:

    a. Is this the best way to handle staining the timber?
    b. Will the stain affect the joint strength if it gets onto the faces of tenons etc?
    c. Will glue squeeze out be more or less of a problem for the finish if the timber is already stained?
    d. Should I put the oil finish on the unassembled pieces as well?

    Any suggestions or tips would be greatly appreciated.

    Regards,

    Laci

    #548078
    Ed
    Participant

    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.

    #548079
    Laci Nagy
    Participant

    Thanks, Ed.

    I appreciate the time you took to put this all down. The ‘Stain’ I’m using is spirit based and needs to be given a top coat after or it can be added to a clear varnish for a 1 step process. On that basis, I think it’s what you’re calling a dye.

    I think you summed it up with the “…it depends.”. My main concern I guess was that with the assembled table, my application method allowed for unseen drips or runs to form. Essentially that is my own poor control of the process, which is why I thought I’d do the dying while unassembled as it would be easier to control that way as the table top had no problem at all.

    I also used the dye neat, except for the end grain where I put straight Methylated Spirits on the wood first then used a diluted dye to try and stop it absorbing far too much dye to match the faces. Much the same way as you coat with water first. I’ll try this over the whole job next time and give it 2 or 3 lighter coats of dye to build up to the finish I’m after. Hopefully, any drops or runs (not that I will have them this time :)) will be easier to feather or remove if the dye is not as heavy.

    Once again, thanks for the advice Ed. It’s been added to the ‘Useful things to know and think about’ file.

    Regards,

    Laci

    #548080
    Ed
    Participant

    The ‘Stain’ I’m using is spirit based and needs to be given a top coat after or it can be added to a clear varnish for a 1 step process. On that basis, I think it’s what you’re calling a dye.

    Not necessarily. I’d put a top coat over a stain. Probably the single best test is the stir test. When you first opened the can, or after the can has sat for some time, are there solids on the bottom of the can? Can you scoop solids off of the bottom and see them on your stick? If so, the product is a stain or is stain like. If it is like a pure liquid, it is a dye. Some things are in between.

    I also used the dye neat, except for the end grain where I put straight Methylated Spirits on the wood first then used a diluted dye to try and stop it absorbing far too much dye to match the faces.

    Another way to handle end grain is to sand to a higher grit. If the face grain has been sanded to 180 or maybe 220, then you can try sanding the end grain to 320 or 600. This burnishes the end grain, closing the open ends of the wood fibers that soak up the stain or dye. You need to experiment to determine how much sanding to do. Remember that curves can expose grain that will be somewhere between end grain and face grain. A cabriole leg is a good example. The top of the foot, the top of the shoulder, and the bottom of the shoulder are close to end grain and can easily go very dark. To prevent this, you can sand those parts of the curves with higher grits while only going to 180 on the more face-grain portions to try to balance the color. Most of the curves on Paul’s stuff are gentle and face the floor, but there are a few where you could choose to use this method and benefit from doing so.

    By the way, one problem with applying color with things taken apart, even if only removing drawers and tops, is that you have no feedback to help to make each component be equally dark as the others when applying the color. It’s easy to be off a bit. Usually, it’s not much and it doesn’t matter, but sometimes it does. This is where that trick of using another coat of dye on top of a barrier coat is handy. It can equalize the color. Since you are working on top of the barrier coat, you have a lot of control, so you can do much of this tint coat with things put back together and, also, the changes are small and easy to wipe off if needed.

    • This reply was modified 1 year, 6 months ago by Ed.
    #548243
    Laci Nagy
    Participant

    Thanks, Ed.

    The tin has no solids in it, it looks like a black coffee that’s slightly transparent. Maybe it would be better to put a single coat of tung oil on first as a barrier coat, then use the dye as you suggested. The manufacturer actually suggests doing that for porous woods. I’m happier with a slower, but a more controlled process, so putting 2 or 3 coats of stain on to slowly build up to what I want sounds like it would be worth doing.

    Thanks again

    Laci

    #548248
    Ed
    Participant

    Hi Laci,

    Just keep in mind that, once you put down a barrier or partly close the wood, as I expect will happen with the tung oil, you reduce how strong the color can ever be, generally, often by a great deal. You can still achieve good results. It just depends on what effect is desired. Also, while I mix water and oil based products on the same project (different layers), they are specific products that I know work together and that are actually claimed to be compatible by the manufacturer. You’ll need some way of confirming that the products you want to use are compatible. It sounds like the manufacturer is giving the nod, though.

    Taking what you said literally: Multiple coats of stain (rather than dye) have increasingly little effect, most of the color coming from the first coat, since the stain has finish / binder in it that seals the wood. Similarly, once I put a barrier coat over my dye, the change in color that is possible afterwards is subtle because there’s no place for the pigment to go other than to lay in a thin layer on top of the barrier coat.

    #548679
    joeleonetti
    Participant

    There are some things I plan to make where it will make sense to finish it before final assembly. I plan to use blue painters tape to cover up the bits that will later get glue on them. Hope this helps.

    #548691
    Laci Nagy
    Participant

    Hi Ed, just realised that I said “Stain” when I meant “Dye”. So I’m hoping I can sneak up on the colour in multiple sessions.

    #548692
    Laci Nagy
    Participant

    Hi Joe,

    Great idea. I think that may be something I look at as well. Firstly to prevent the wood joints from getting sealed before the glued up with the dye (unlikely but why take the chance) and then with the glue up to protect from squeeze out over stained pieces.

    Thanks

    Laci

    #550821
    Brian A
    Participant

    Glue is the enemy of finishes, unless that finish be glue.

    .

Viewing 10 posts - 1 through 10 (of 10 total)
  • You must be logged in to reply to this topic.