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Glue - before or after finish

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Forum topic by jonlan posted 03-29-2016 03:37 AM 781 views 0 times favorited 13 replies Add to Favorites Watch
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jonlan

35 posts in 355 days


03-29-2016 03:37 AM

Im a newer wood worker – so this might be an obvious question. My wife asked me to build a book shelf for our sons room and she wanted one made of oak, something heavy duty that he could keep once he moves out etc. My usual approach to building is to glue as I build then finish (including sanding) at the end. The bookshelf is largely dowel construction and I’m quickly realizing that this approach wont work. There are just too many places that are much easier to sand before putting the thing together.

My real problem is glue though. Despite my best efforts, I’ve managed in a couple of spots to have glue come out of the joints when clamping. While this usually isnt a big deal, there are some inside corners where its done this and Im worried about how to get it out without it showing up in the finish when I stain it.

So this made me wonder – do other people finish the boards entirely and then glue it all together? That certainly seems like it would help on the glue end of things but Im not sure.

Any thoughts? I know I need to get better at glueing and limiting how much I put down.


13 replies so far

View cdaniels's profile

cdaniels

1311 posts in 969 days


#1 posted 03-29-2016 04:33 AM

first off you actually want the glue to squeeze out the joints when you put them together. if you don’t than the joint will be starving and most likely not stay together. Me personally I like to sand and apply my pre stain (if i’m staining) or put down a coat of shellac after I sand and before I glue if i’m putting a topcoat on after. when you do clamp the joints together just get a paper towel wet and wipe out the glue from the corner, the wet rag cleans all the glue off the outside so you don’t get discoloration.

-- Jesus was a carpenter... I'm just saying

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shipwright

7175 posts in 2265 days


#2 posted 03-29-2016 04:58 AM

I stopped worrying about all that when I switched to hide glues. I would never go back to PVA glues as this is only one of the many advantages hide glues give me. They clean up with water either right after glue up or the next day and don’t block finishes.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees. http://thecanadianschooloffrenchmarquetry.com/

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gfadvm

14940 posts in 2157 days


#3 posted 03-30-2016 12:02 AM

I apply a coat of shellac to the inside of my boxes (NOT on the surfaces to be glued) prior to assembly (glue up). Any squeeze out then scrapes off easily with a sharp chisel or razor blade. I like to scrape the glue out of the corners when it is at the dry but soft stage (peels off very easily at that stage).

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

View Dark_Lightning's profile

Dark_Lightning

2635 posts in 2576 days


#4 posted 03-30-2016 02:30 AM

Off the original topic,but you can build a bookcase out of knotty pine for a ton less money than oak, and it will still hold the books.

On topic, I usually glue, then finish. I’m building a tool chest at the moment, and I have reversed my usual process, as I have veneered the substrate (Baltic Birch Plywood), and used contact cement to adhere the veneer. I didn’t want to get into wetting the veneer at the edges with more water based glue when I put the thing together. Maybe that would have been OK, but I always sweat the details, especially where I have little experience.

-- Random Orbital Nailer

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JBrow

819 posts in 387 days


#5 posted 03-30-2016 03:15 AM

jonlan,

I sand parts to final grit before assembly, except near joints that will have to be flushed up after assembly. Once the project is ready for finish, I generally give the entire assembly a light hand sanding immediately before applying the finish.

I rarely apply any finish before glue-up; however there have been times when I did applying finish before assembly because it made sense for the project. I have not pre-finished parts for the purpose of dealing with squeeze-out, although that may make removing tacked or cured glue easier. Keeping the finish off areas that receive glue is critical for a good glue bond when pre-finishing parts.

I consider the difficulty of removing squeeze-out when I apply glue. In areas where removing squeeze-out would be difficult, I pay close attention to the amount of glue and how it is applied. In these areas, I try to strike a balance between a strong glued joint while minimizing applied glue.

I have cleaned glue squeeze out with a wet rag as soon as the assembly is set in the clamps. I have also scraped squeeze-out with a card scrapper, paint scrapper, or chisel after the glue has tacked up, usually after an hour or so. I have also waited until the glue has cured and then scrapped, but usually sand the squeeze-out off to avoid tear-out. All these methods have advantages and disadvantages depending on the nature of the assembly.

View splintergroup's profile

splintergroup

832 posts in 690 days


#6 posted 03-30-2016 02:11 PM

It depends on the project, but I’m a fan of pre-finishing when possible.
For something like your bookcase, if it has a typical recessed back, I’d finish last since all parts are easily reachable. The back would then be finished and attached.

There are several tricks to controlling glue squeeze out. A simple one is a good grade of painters (blue) masking tape placed right on the joint line before assembly. I also like Waxlit, a more viscous paste wax that is rubbed in the wood near the joint with the parts assembled, before gluing. The wax makes any squeeze out pop right off and the wax is removed with a few wipings of mineral sprits after the glue has dried.

For projects that have impossible to reach areas after assembly (like a bookcase with a back permanently attached), I’d do all sanding and finishing first, then glue/assembly. You could try to avoid getting finish on any areas that will be glued or you can remove the finish from the glue surfaces after finishing with sand paper or a quick swipe with a plane or scraper.

View Joel_B's profile

Joel_B

294 posts in 848 days


#7 posted 03-30-2016 06:51 PM

I use blue tape. Don’t wipe off the squeeze out when wet, let it dry until its gummy about an hour then remove with a cabinet scraper. Waxlit approach sounds interesting.

-- Joel, Encinitas, CA

View BinghamtonEd's profile

BinghamtonEd

2281 posts in 1837 days


#8 posted 03-30-2016 07:24 PM



I use blue tape. Don t wipe off the squeeze out when wet, let it dry until its gummy about an hour then remove with a cabinet scraper.
- Joel_B

I do this, too, when I’m concerned about squeezeout, and it works well for me. I do a dry assembly to test parts for fit, and once I’m happy with it, I apply the tape prior to disassembly.

When the application allows, I’ll skip the tape, glue it up, scrape off the squeeze out when it’s gummy, and then give it one or two swipes with a #4.

-- - The mightiest oak in the forest is just a little nut that held its ground.

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TTF

154 posts in 2645 days


#9 posted 04-02-2016 03:51 AM

I stain parts, keeping glue surfaces bare, then glue up. If stain gets on the glue surfaces, I use poly glue. After assembly, scraping and sanding, I stain again. Pretty happy with the results.

-- Troy | http://tf-workshop.com | The more I see nature, the more I am amazed at the Creator. - Louis Pasteur

View jonlan's profile

jonlan

35 posts in 355 days


#10 posted 04-02-2016 02:34 PM

Thanks for all the replies guys. Lots of good tips here. I’ll give some of them a try.

Thanks!

View Tootles's profile

Tootles

780 posts in 1969 days


#11 posted 04-03-2016 12:50 AM

Dark Lightning, Please don’t take this the wrong way, it’s just that I had to chuckle (though that may just be my weird sense of humor) when I saw that you wrote this …


Off the original topic, but you can build a bookcase out of knotty pine for a ton less money than oak, and it will still hold the books.

- Dark_Lightning

You are right of course. You know it, I know it and I am sure most LJs, including Jonlan, knows it. And apart from being cheaper, knotty pine would probably have been easier to work with. Except for one small detail in his original question …

My wife ... wanted one made of oak.

- Jonlan

And that is why Jonlan used oak.

-- I may have lost my marbles, but I still have my love of woodworking

View madburg's profile

madburg

146 posts in 310 days


#12 posted 04-03-2016 07:01 AM

I always finish what I can before gluing up. Particularly insides of boxes etc where you can’t get in to clean up the internal corners. I totally finish my internal surfaces, (I only use multiple coats of polyurethane) including the final wax polish and buffing. I then don’t worry about any squeeze out as it doesn’t stick to the buffed wax surface. I leave a few days so any glue runs a quite dry, and then its easy just to peel off the squeeze-out. If you try to take the squeeze out off to soon it won’t be dry and you’ll just spread it all over again. Some times I might use a damp cloth to clean off the squeeze out, but again any residue left doesn’t stick to the buffed wax surface and can be peeled off easily. I have used masking tape, but you can get tiny bits of it the sticking to the glue right in the corner and then its very difficult to get off! I also use plastic razor blades to ease up the corners of dried squeeze outs.

If you don’t finish before gluing up, then wiping off of glue with a damp cloth can well end up staining your wood, leaving a small filet of glue in the corner. Damping will probably lift the surface, requiring some refinishing.

It also hard to sand into corners – you can’t get right in.

-- Madburg WA

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OSU55

1063 posts in 1457 days


#13 posted 04-03-2016 01:42 PM

I always glue before finishing. Projects are designed with finishing as an integral part of the design, so access is made available for finishing. The edges of a contained panel do get stained and sealed, and there are a few other exceptions, but for me it is by exception rather than rule. Sometimes glue on the surface is an issue, dealt with by touch ups during finishing. I find touch ups and blending easier than trying to keep glue surfaces clear when pre-finishing. Both can work, it depends on preference, and there are always exceptions either way.

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