I’m a quality minded freelance finish carpenter who’s currently working with a crew that insists on gluing all the miter joints in their casing. They insist that the joints don’t open up with the seasons. I’m all for taking extra steps to keep joints looking good, but I don’t really buy it.
For one thing, the trim is MDF, so the glue soaks into the material before it even has a chance to bind, and, by the time you slightly back-cut your joints, there’s not a lot of positive gluing surface. Plus, in my experience, if wood wants to move, it’s going to move regardless of how you attach it. They say they do the same thing with hardwood trim, and I don’t buy it in end-grain either.
I’ve used biscuits with time-tested sucess, but this budget doesn’t warrant biscuiting all the joints.
Is this hooey? or should I be doing this too? how about baseboard joints and scarf joints? any opinions?
Replies
Caulk -- I can never get them to match well enough for glue.
I glue MDF and have never had a joint open up. You can hit the edge with glue, and if it soaks in and skins over, hit it again as you mate the two pieces together.
I'm sure you're aware that MDF is a slightly different bird than wood, as wood moves more along one dimension than the other due to the grain.
MDF, being "grainless", does not have that differential.
With wood, I plan for wood movement, especially with cross grain joinery.
With MDF, I don't. Biscuits and gravy (titebond) where able, and if no biscuits, then just the gravy.
I glue all miters with Titebond molding glue.
With MDF trim I use extra glue.
The Molding glue forms a strong bond, dries clear, fills small gaps, is "high tack," and does not run.
I also like to clamp (Collins) and pin miters 23ga. or 16ga. Glued, clamped and pinned joints stay together pretty well.
Damn-
you must type faster than me. <G>
I glue pretty much any miter I make- casing, base, crown. And any scarf joints. I use the Titebond moulding glue- it's a bit heavier consistency, so it's less likely to drip.
I don't back cut the joint to make it fit better- I'd rather adjust it at the miter saw, or use a block plane to fine tune it. Either way, I have maximum glue surface.
I also like to let my trim acclimate for a few days or longer inside the house, to minimize movement once installed.
I do glue both surfaces when using MDF trim, since it is so porous. Not a heavy coat, but enough to coat both surfaces to get a light squeeze out. I also like to clamp the miters with the Collins miter clamps. They apply enough pressure to make the glue work in the joint.
Looks like we could work on the same crew!
I glue them. With the season changes in my area i've seen them come apart if they arn't glued. I've taken casing of of jambs that were installed 20 yrs ago and the miters are still stuck together.
I don't glue mitres, especially paint grade. How much is the MDF going to move to make the joint open up anyway?
I'll go the extra mile for a lot of things that will never be recognized by the HO but glueing the mitres on casing isn't one of those things.
I f you ever go back to a job after a year you will find that an unglued MDF joint will pull apart.. The casing is nailed to the jamb and the trimmer which both move.
I have been back at jobs after year and nothing to note. Might be an environment issue.
I glue everything I can catch up to.
On a hill by the harbour
Is this hooey? or should I be doing this too?
You oughta be be doing it the way the guy with the checkbook wants it to be done. And that's the bottom line. If you're just fishing for opinions.... mine is that glueing miters is just good practice and can only help.
i do it all the time... cept i use construction adhesive... liquid nails or whatever i have...... i get squeeze out... after a few min i clean it up with a small razer snap blade knife i always keep in my pocket... i know i'm cheating to a point because my joints only have to be close to end up looking pretty darn good......
p
I glue the mitres and use two of the smaller biscuits in every joint. I've never had trouble selling to a client that their house deserves what is best, not what is quickest. After using Rockler clamps for a couple of years I opened up the wallet and bought 4 of Jim Chesnuts clamps. They are awesome, even considering what it cost me to import them into Canada.
If you check out issue 164 you can read Jim's excellent article on this process.
Have a good day
Cliffy
I glue all my joints, like Basswood says glue, clamps and cross pins for casing.
Scarf joints glued and nailed.
Any casing 3" or wider gets biscuits and glue.
MDF gets a coat of glue on each surface, then nailed on.
At least the glue helps seal the endgrain of the wood. And what could it hurt?
Matt- Woods favorite carpenter.
I'm happy to do it how ever the person writing the check wants it done- looks like according to the responses, maybe I should consider doing it all time. I'll have to do some test glue-ups before I become a total convert- thanks for all the feedback.
I was taught to glue them and most alway have. The ones I haven't glued do tend to shrink and cause a paint crack in the Michingan winters. The glued joints stay tight.I've never installed MDF so I can't speak with any authority on that aspect of it.Edit: if you quit backcutting, the glue will have a better chance to bond. FKA Blue (eyeddevil)
Edited 10/28/2007 12:56 am ET by Jim_Allen
well maybe I take it to far I glue all joints .glue casing to wall and to fillers or door jamb
glue base to wall all the time .I don't care who is paying .that's just the way I was taught I can glue most pieces in about 5 seconds or less keep bottle in my pouch and it is always full .takes to long with a almost empty bottle
I'm in your school, glue all miters.
One builder I finished houses for specified casing glued to wall. I never got the hang of glue to jamb, too much run out.
The only time I ever had broken miter joints was on a series of houses that were tyveked without siding. The builder called me back to repair the window casing and I could not believe the miters opened. By the third house I finally figured out it was the siders hammering the heck out of the exterior walls that was causing the miter pops and started charging for the repairs.
Gord
Molding glue, or caulk, every miter/scarf, and cross pin. If the budget allows, biscuits and clam clamps.
Go Sox.
"I am the master of my fate, I am the captain of my soul." Invictus, by Henley.
What's that two part stuff that is brushed on and then spritzed to activate? Sets up in maybe a few seconds, just enough time to position.
I think I read that Blodgett uses it. Hey Jim?
What's that two part stuff that is brushed on and then spritzed to activate?
You may be thinking of this: http://www.amazon.com/2-P10KIT-2-P10-Adhesive-Kit/dp/B00008US7G.
But you can get cyanoacrylate glue (also called CA, superglue or krazy glue) through hobby centers for less money.
It works well. The downside is that it's very expensive (unless you're doing very tiny molding) and it doesn't have a good shelf life.
I've used contact cement with good results when I wanted to pre-assemble the molding such as faux paneling.
Fastcap P-10. Katz uses it (or did, I watched him pre-assemble crown pieces using it at JLC a few years ago.)
I tried it, but it didn't work so well for me, so I went back to Titebond/caulk.
"I am the master of my fate, I am the captain of my soul." Invictus, by Henley.
FastCap 2P-10. IE: Two Part-Ten Seconds
As already stated, it's got a short shelf life and is pretty expensive. I do keep some around for self returns of various parts and pieces. I don't own a 23ga pinner, so the 2P-10 often fulfills that role for me. Also nice if you want to build up a small corner of built-up trim on a bench instead of in place. Once it's all together, I'll take it to it's final resting place and nail it home... as well as nailing off all the joints.
That being said... I prefer TiteBond II for pretty much 95% of routine miter and scarf joints. It's cheap, easy, and effective.View Image
View ImageThink Lester will do it?
And if he doesn't, guess who's next?
Edit, spelling
"I am the master of my fate, I am the captain of my soul." Invictus, by Henley.
Edited 10/28/2007 3:19 pm ET by NickNukeEm
I've no idea Mongo. Really. That's why I love baseball though. He could... meaning he has the potential with some pretty nasty stuff.... but whether or not he brings it tonight is up in the air. Ask me again in about 4 hours. ;)View Image
I use the Titebond II for exterior joints, but go to the molding glue for interior. Less chance of drips making a mess to clean.and for the OP, I am one more who always glues wood joints. I think it is even more important to glue MDF joints because it is a wood that can flake apart.
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I glue every casing miter as I assemble. On paint grade, the excess glue squeezing out of the miter is wiped off with my finger and then I wipe the glue off my finger on the front pocket of my tool pouch.
While my hand is down there, I scratch, then grab the piece of 100 grit cloth backed sandpaper (which I buy in 100' rolls 2" wide) and I sand the miter. All of this is performed in about 5 seconds, and I am rewarded with a gap free, I can come back in 10 years its tight miter.
I`ve always glued and sanded miters so the process is painless. My glue bottle, sandpaper, all reside in the same place in my pouch for years. I don`t have to look for them.
I never cross nail MDF miters, they split, and I use finer grits of sandpaper when using hardwood trim.
As an added bonus, the only thing I get from the painters is a big smile.
Gord
Keep both eyes on the other carpenters, they know what their doing. I always glue miter joints,no matter if hardwoods,softwoods or mdf.
mike
ALLWAYS GLUE YOUR JOINTS. If the joints are tight and you glue it the joint will be stronger than the wood (or MDF). I recently took a small track job and I still glue all my joints. It adds only seconds per door and I can walk away feeling like I did things correctly.
I also find that (no reflection on you) the guys a run across who don't glue tend also not to use sand paper and and generally do lesser quality work. THhey pride themselves on how fast they work over the quality of their work.
I always glue miters, scarfs, notches, and anything that is joining two pieces together. Exactly like Shep said, I never undercut, but rather rasp & block plane it to perfectly fit. Always dry fit everything first, it only takes a second, and when it's perfect or near perfect, that's when the glue bottle should come out with the brad gun hanging off your belt ready to shoot as soon as it's in place.
MDF is no problem, I was just doing 3/4" MDF casings this afternoon in my own house,that I milled myself. For something that large & thick I like to use biscuits in my joints with the glue and one nail to hold it till it dries.
The molding glue is good although lately I've been using up the plain interior yellow glue which I have a ton of.
I've found Titebond 3 to be really good too, not just for exterior. The setup time is less and the strength is proven to be much stronger.