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Morris Chair - Final Glue-Up

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In the final glue-up, Marc uses epoxy, primarily for its long open time.  Has anyone used the Unibond 800 for this purpose as well (or know of a reason why we shouldn't use it)?

Reasons to  use Unibond 800:

  1. I have it on hand from the previous step.  I don't have any epoxy and have no experience with epoxy (but I'm more than willing to learn).
  2. Unibond fills gaps like epoxy.
  3. Unibond has a long open time like epoxy.
  4. Epoxy cleans up with alcohol, lacquer thinner or acetone.  Unibond cleans up with water (prior to curing, of course).
  5. The grooves in which the vertical slats sit have slight gaps in places.  These close easily with light clamping pressure and glue.  Unlike other woodworking glues, epoxy needs a fairly thick glue line (0.003" according to West Systems Epoxy) to properly cure and develop strength. Unibond can be pressed tightly (e.g. used extensively in veneering) and doesn't need the thicker glue line.

Point #5 is my primary reason for wanting to use Unibond.  Having cut the grooves in the side rails in multiple passes, the grooves are not absolutely perfect.  There are thin gaps in some places.  While adding the filler pieces between the slats, I used Titebond.  I clamped any of the pieces that showed gaps and everything closed up tightly.  I would like to use the same method when I glue in the vertical slats in the sides.  It seems that I might have trouble doing that with epoxy as it needs that thicker glue line.

Can anyone suggest a reason as to why using Unibond 800 to glue up the Morris chair side assemblies is a bad idea?

Thank you in advance.

 

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1 hour ago, Minarzick said:

Can anyone suggest a reason as to why using Unibond 800 to glue up the Morris chair side assemblies is a bad idea?

I can't because I'm not that familiar with Unibond, but I can recommend that you go ahead and buy a WS kit because it's great stuff to have and use on a regular basis.  I use it almost as much as Titebond at this point.  PVA for all "normal" glue-ups, WS for any complicated glue-up where I need lots of open time, or for tight joints where I don't want the fibers to swell.

I've never heard that thing about the .003"...and I kind of have trouble buying it.  Any joint that has a .003" gap is a pretty sloppy joint.  I personally don't make joints like that, and my furniture hasn't fallen apart yet.  A joint is just right when it goes together without pounding it with a mallet but you can't stick a one thou feeler gauge in it.  Three thou is terrible.

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Short answer: there's nothing wrong with using 800. Decent open time, gap fills to 0.02, color to match, etc.

 

 

Channeling Don at the moment -- so you get the answer without the explanation on point 5 (misapplied info for the application at hand). Unless you get into structural bonding, just ignore the glue line business... For assembling furniture, remember to wet both surfaces and you'll be fine...

 

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Eric,

Please forgive me but what is a WS kit? It sounds like I need to look into having it on hand. 

I agree with you about the sloppiness of a 0.003 inch joint but there are times when I have to settle, move on and make the best of what I have. I'm improving with every project that I complete. The gap filling properties of Unibond 800 and epoxy are useful in certain circumstances. 

I'll post pictures of the Morris chairs when they're done. Probably in about 10 days.

Hhh,

Thank you for your reply. I made a super sloppy test joint last night from a test piece that I used to set up the slot cutter. I slathered Unibond 800 all over ALL of the surfaces and clamped it hard to close all gaps. I haven't removed it from the clamps yet so I'll update this post with my findings.

Easy clean-up is confirmed. Unibond 800 cleans up very easily with warm water. In fact, I'd say that it cleans easier than TiteBond. And water clean-up is a lot nicer than solvent clean-up in my book, though you may raise the wood grain more. 

Thanks again. 

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==>what is a WS kit?

West 105 resin

West 205, 206, 207 and/or 209 hardner

Pump set

 

Note: for longer open time, you should get the 206 (or if budget allows) 207 hardener... If you have budget for only one harder, it should be 207...

Note on note: 207 is not suitable for structural applications -- but plenty strong enough for furniture...

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Ah, West System. You're right. Epoxy does have some very beneficial properties. Does the product have a long shelf life? I work slowly, on evenings and weekends when I have time. I was surprised that Unibond 800 has a short shelf life. It starts to solidify without hardener. I'm on my second round for 1 pair of Morris chairs. I believe that temperature has a lot to do with it. It was stored in a garage in Texas over the summer. Let's be clear: it was hot! I see some people storing CA glue in the fridge. Perhaps the same should be done to increase the shelf life of Unibond. 

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Keep in mind that unibond is some nasty stuff. Hope you are wearing your gloves and dust mask, especially when mixing it up. I wouldn't make it my go to glue. Like Eric, i use epoxy when i need the extra open time.

I look forward to seeing pictures of your completed chair ! Please post them!

Sent from my SM-N910W8 using Tapatalk

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Agreed, dust mask when mixing and sanding. I have the Unibond 800 already from the bent lamination steps. I agree with you: it will not be my go-to adhesive. It's also expensive, hard to get (easy online but I can't find it locally) and has a short shelf life. 

After a few months in the garage, the liquid part of the Unibond 800 had the consistency of mayonnaise. So consider that when you're looking at it as an adhesive. It does not last. 

When new, it starts off very liquid, like maple syrup.

 

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Shelf life is heavily influenced by ambient storage conditions... I've got 20year old West Systems, five year old U-800, etc... You don't have to store them in a fridge, but storage in a dry, dark and cool environment adds years... Conversely, storing adhesives in a shed, garage, etc shortens the shelf life considerably... For most adhesives, freezing or excessive heat is bad...

I do store fish glue in the fridge and cubes of HHG in the freezer...

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Quick follow-up:

I know that as woodworkers, we can sometimes beat the details to death - a sort of analysis-paralysis.  I am guilty of this from time to time, though I'm trying to get better through self-help books and videos (kidding).  

After further thought and carefully watching the videos, I may have an answer as to why epoxy is used for the glue-up instead of Unibond 800.  First, I believe that Marc, like many of you, has epoxy in his shop as a standard stock item.  I am less sophisticated.  I generally don't stray from TitleBond - my projects haven't required it.  Though just recently, I did add CA glue and activator to my arsenal.  CA glue is a fantastic product - it allows me to make repairs on the fly and continue working without having to wait for the glue to dry.

The other reason that I believe Marc chooses epoxy is the thickening agent.  The mortises on the chair back are small and he applies glue to them using a popsicle stick.  Unibond 800 is too thin for that application - about the consistency of maple syrup (you could always load it into an application syringe and spread it with a Q-tip (not sure how well that would work in practice, but it's one idea).  Epoxy can be thickened substantially with filler.  West Systems' website shows that thickener can be added in order to change the consistency from think liquid to something akin to peanut butter.  A thicker adhesive would allow it to be handled easier, being less runny.  It might fill gaps in the joinery better than a thin liquid.

That said, I have secured West Systems epoxy and I'm 90% certain that I'm going to use it in the same ways that Marc does.  What I don't know yet is (1) which hardener to use - I have the fast setting hardener (#205).  Perhaps the #206 slow hardener is preferred for a longer open time.  Marc also uses a thickener but doesn't say which one.  After some research on West's website, I have settled for #406 (colloidal silica adhesive filler).  

Please comment if: (1) you are Marc Spagnuolo or (2) you have reasonable experience with epoxy formulations.  Keep in mind that the garage is cool this time of the year (60 F) so that should help slow the epoxy reaction.  Only very small batches will be made - think one quarter to one third of a Dixie cup.  Which thickening agent do you prefer?  Would you recommend the slow hardener (#206) over the fast hardener (#205) for this application?

Thank you for your input.

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From West Systems website:

West Systems 205 Fast Hardener
Pot Life at 72F (22C): 9 to 12 minutes
Cure to a solid state: 6 to 8 hours
Cure to maximum strength: 1 to 4 days
Minimum recommended temperature: 40°F (4°C)

West Systems 206 Slow Hardener
Pot life at 72°F (22°C): 20 to 25 minutes
Cure to a solid state: 10 to 15 hours
Cure to maximum strength: 1 to 4 days
Minimum recommended temperature: 60°F (16°C)

West Systems 209 Extra Slow Hardener
Pot life at 72°F (22°C): 40 to 50 minutes
Pot life at 95°F (35°C): 15 to 20 minutes
Cure to a solid state at 72°F (22°C): 20 to 24 hours
Cure to a solid state at 95°F (35°C): 6 to 8 hours
Cure to maximum strength at 72°F: 4 to 9 days
Minimum recommended temperature: 70°F (21°C)

I think that I should be in the "Extra Slow" category - though my mom tells me otherwise.

West Epoxy Filler Selection Guide.JPG

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1. I'm not Marc.

2. Twenty years experience with various epoxy compounds including West Systems.

3. I rarely use additives for furniture making... Use them all all the time in marine applications, but not furniture... When I do, it depends on the species and application. What species is your project? What is the application? I seriously doubt you need additives. For furniture, usually 406 or 405.

4. Unibond is just fine, you can mix it thicker if you like...

5. Small batches are prone to formulation errors... You must dispense at least one full pump.. Or mix by weight.

6. If your garage is too cool for adhesive curing, get an electric blanket.

7. 206 and 207 are more useful for furniture.

==>The mortises on the chair back are small and he applies glue to them using a popsicle stick.  Unibond 800 is too thin for that application.

??? -- Morris didn't have epoxy or Popsicle sticks... You can mix U800 pretty thick if you like. Or you could just use HHG/LHG -- kinda like Morris... :)

Executed several Morris chair builds in my time (not Marc's build). If you know what you're doing, there is little need to thicken adhesive for the build. If you do use a thickening agent, you need to wet both surfaces with unadulterated epoxy, then follow-up with a thickening agent (if needed). Any other technique is wrong -- doesn't matter where you read it or who's videos you watch...

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hhh - thank you - interesting information.  My Morris chairs are in figured cherry.  I finished gluing the foot stools last night (using TiteBond).  Gluing the chairs is next.  There are a lot of parts to glue together in each chair side, including the vertical side slats.  I believe that epoxy is being used for its long open time.  I figure why not use the 209 Extra Slow hardener for more time.  It does require a warmer temperature, but I can put the project together in the garage and then bring it into the house to cure.

My thinking (just my idea - I may be wrong) is that the thickening agent is used to thicken the mixture, making it less viscous and easier to handle/drop into small mortises and fill gaps in joints.

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209's fine. Use it for when long open time is the most desired feature and/or bonding in hot weather. Potential drawbacks: 3:1 mix ratio, doesn't cure as clear as 207, high minimal cure temp, long cure time and cost... For furniture, my goto is 207 or 206, in that order. BTW: 207 is suitable for structural applications -- so if you plan to use 207, you should get some 205/206 for general-purpose or structural applications...

 

==> thickening agent is used to thicken the mixture

yes.

But more correctly: modify handling properties during pot life, tint or modify the texture of the cured mix.

 

==>making it less viscous

yes.

 

==>and easier to handle/drop into small mortises

maybe.

It you need to get epoxy into small mortises, the best approach is unadulterated mix and  http://www.amazon.com/gp/product/B001EMEXNI?psc=1&redirect=true&ref_=oh_aui_search_detailpage

The tenon should be whetted only. Smearing epoxy on the tenon-side of joinery is considered poor practice. I've not watched Marc's Morris build, but am surprised he didn't address the issue. Smearing modified epoxy to joinery without wetting can lead to joint failure.

BTW: even for larger M&T joinery, I still use the Monoject syringes -- especially with open-grained species. Yes, they're $0.50 apiece, but smeared epoxy is a bitch to cleanup.

 

==>and fill gaps in joints.

no.

If you have large gaps, then you have other problems that epoxy won't cure. Epoxy should not be used as a solution to poor joinery...


 

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hhh,

Thanks for the syringe idea - I like that.  You mix the epoxy and then pour it into the syringe?  The syringe seems like an ideal applicator to put just the right amount of glue in the right place.

Applying glue to the tenon: I have learned that you are 100% right on this score.  Previously, I was slathering up both the mortise and the tenon with glue. Squeeze out was terrible.  Most of the glue on the tenon gets stripped off as the tenon enters the mortise.  This ends up squeezing out of the joint.  I have started to apply glue fairly liberally in the mortise but I only gently wet the tenon with glue - VERY sparingly.  I'm still getting some squeeze out but FAR less than before. 

Is it desirable to shoot for zero squeeze out with epoxy?  And if it does happen, do you keep rags and acetone around or do you let it cure and scrape/remove it once hardened?  I'm somewhat concerned about this.  That's the big plus with Unibond 800 - it cleans nicely with water.

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==>glue fairly liberally in the mortise

why? if your joinery is solid, there is no need...

 

==>Is it desirable to shoot for zero squeeze out with epoxy?

exactly.

Again, I'm surprised Marc didn't address this when using epoxy... You don't spead epoxy on the tenon-side of joinery -- you just wet it. Actually, not with any adhesive, but epoxy squeeze-out is especially problematic.

 

==>Do you keep rags and acetone around or do you let it cure and scrape/remove it once hardened?

Neither. If there is even the remotest possibility of squeeze-out, I use blue tape, a release agent (Waxilit, at the moment) or some other protection... If you rag it, you may press the mix into the grain and you're screwed. Worst case of a spill, I've got epoxy solvent -- which is incredibly volatile and (I bet) very toxic, so I wouldn't recommend it --- makes lacquer thinner seem like grape juice...

When I screw the pooch, I shoot a seal coat of #0.5ct and go with a clear lacquer finish... That's why I use 207 -- the squeeze-out is hidden under the lacquer film...   BTW: that's my tip for the week -- and one that's a very hard lesson earned... :)

 

 

==>That's the big plus with Unibond 800 - it cleans nicely with water.

exactly. the downside is its carcinogenic... :)

 

==>you mix the epoxy and then pour it into the syringe?

yes.

 

 

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Thanks for the good information. I really want to try this project someday when my current life chaos is complete.

Chair side looks really good.

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