Hi there. I’m a new “member”, 25 years as a carpenter, and the occasional piece of furniture or cabinetry. I’m taking my projects to a new level, but am about to walk into a couple of landmines. I think I can avoid them (and any others I don’t know about yet) if I stop now for some ideas.
I’m building a solid red oak display case (no veneers) with stained glass panels in wood doors, mirrored back & glass shelves. The joinery is with biscuits, dowels and yellow glue, clamped until dry. I plan to use an oil-based stain with a polyurethane finish. Now the problems.
I has some glue squeeze-out, most of which I left until I could safely cut or scrape it away, then sand later. Some, however, was thoroughly (maybe!) wiped off with damp rags (NOT distilled water). After some reading in my new subscription, I realize there is probably unseen residue. How can I find and remove it? Will mineral spirits do it? What about distilled water? What further problems might I create doing either? Second, my clamps had rubber pads on when I glued up. I can see spots where a few leached into the wood. There may be more I can’t yet see. How can I dodge this bullet before staining? Will mineral spirits reveal and/or remove them? I don’t think sanding is the answer; it’s probably in too deep. Thanks in advance for any ideas, Erclb.
Replies
It looks like we had similar career paths, although I didn’t stay with carpentry as long as you have.
While it is impossible to prevent glue marks, here are a few things I do to minimize them. Apply as little glue as possible to reduce the squeeze out. This also helps with alignment, since the glue acts as a lubricant and causes things to slide around. There is a certain stage where the glue will be partially cured and have the consistency of rubber. At this point you can safely remove it just by rubbing with your fingers or a some other tool that won’t mark the wood. Another thing I do is to mask off areas where I won’t be able to conveniently reach while clamping. For this, be sure to use the low tack (blue) tape. On moldings, I carve a quick “glue gutter” with veiner gouge near the edge I don’t want glue squeeze out, this works very well. The last thing you’d want to do is to wipe the wet glue, especially when working with open grained woods like oak. This will force glue into the pores of the wood and make what I call a glue slick . I always cringe when I see Norm do this ( sorry Norm).
I use small blocks of softwood and clamp pads and just hold them in place with the same low tack tape I described above. I know the marks you are referring to, as I get the same ones from the little orange pads on my clamps. These don’t go very deep, and can easily be sanded/scraped away. I also get this from my hand screws, where the oil from the finish is transferred to my project
Using mineral spirits will highlight the glue, especially on dark woods. On lighter woods you may have to look carefully under raking light to see them. Distilled water also works, but I think the mineral spirits is more effective.
I’m not a big fan of sanding glue marks ( or any sanding for that matter). PVA glues don’t sand well since they remain gummy. The best way is to plane or scrape the spots away.
If after staining you find an area you missed the glue, you can fix it by, acting quickly, scraping the area and then sanding with 220/320 wet and dry paper dipped in the stain .
Rob Millard
I like squeeze out. The #1 priority is that the piece works and I'm not going to risk a strarved joint trying to get just right amount of glue. If there's no squeeze out there's no way to know you've got enough glue in the joint. I'm not as opposed to wiping and sanding, especially with solid wood. I haven't tried the toothbrush trick per Jewii'ts article, but it stands to reason. I do most of my work in QSWO and I don't bother with distilled water either. The iron stains left by the tap water in my area are really minor and sand-off easily. I don't have the time or desire to watch glue dry to that perfect rubbery state. A paint scraper takes the worst of it off. A Fein Multimaster with the offset scraper blade does a good job on inside corners, then I use it with the triangle sanding pad, which leaves a different scratch pattern, so I go back over it with the RO. Prevention is the best medicine so whenever possible I pre-finish after dry-fitting. Since I almost always spray, I get better finish quality spraying parts vs. an assembly and it's much easier to rub everything out too. I use "Roo Glue" on prefinished stuff because if I miss a little bit it dries clear.
Clamp marks on pre-finished work are another story all together. Even the pipe clamp rubber pads leave marks. I tried stick on felt on my K-Bodies and it left marks too and in a couple of cases they got glued to the piece. I'm going to try some thick leather next. Either way they rub out with a little wax and 4/0 steel wool as long as the finish was well cured in the 1st place. A couple of 2" long PVC pipe sleeves on pipe clamps keeps the iron pipe off the work very well. I have had the serrations on the K Body bars leave marks, nothing that doesn't rub out but I think I will try some split PVC pipe for that as well.John O'Connell - JKO Handcrafted Woodworking
Life is tough. It's tougher if you're stupid - John Wayne
Thanks for the feedback! My project is still unfinished, I'm trying to get the pad spots out before staining. I agree about glue squeeze-out; I just want the most thorough methods of removal. I think scraping is fine, and for me a complete sanding is going to follow anyway. I like the toohbrush idea in the last issue. I have a creek as my water supply, so distilled is probably a better choice. We have lots of iron in the water! I'd still like to hear from anyone on mineral spirits vs. water as a method for catching flaws before staining. Wolud it matter whether you use a water-based or oil-based finish?
The safesest approach would be to use the solvent or carrier for the final finish to wipe down to see the defects, but lacquer thinner or denatured alcohol evaporate too quickly, so paint thinner is the generally accepted solvent. Personnally I wouldn't use it if I was going with waterborne topcoat. Oil and water don't mix, except for W/B dyes under solvent finishes if it's completely dry. When I sand, I turn off the overhead lights and set a 400 W halogen work light at the end of the board. All my sanders are hooked up to a vac so there's very little dust to settle in the imperfections so even the smallest planer mark or scratch casts a shadow. Oh yeah, I set up a fan too 'cause that light sure puts out the heat.
One other tip I came up with when I did a run of 14 chairs (approx. 4000 surfaces to sand!). I bought the Carter vaccum hold down kit from Rockler and build a vac hold down board which runs off a second Fein vac. When sanding with a very strong vac (Fein) hooked up to an R/O sander it tends to grab the piece and wiggle it around thereby wasting the energy moving the wood instead of abrading it. The sanding/router pads don't help much either. With the vac hold down, nothing's in the way, switching pieces is faster than clamps, there's no marks, and the sanding goes much faster. Also your not transmitting vibtration into your left hand/arm and chasing the work piece around the bench.John O'Connell - JKO Handcrafted Woodworking
Life is tough. It's tougher if you're stupid - John Wayne
I use naptha. Doesn't raise the grain, and there are no solvent/finish issues to contend with.
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