Working with Epoxy: Squeezeout, runout, cleanup?

[John Sanford]

I'm considering using epoxy to adhere the endcap and condor tail of my Split Top Roubo, but I have minimal experience working with the stuff. I know that some epoxies flow like water, others (which I have used a little) are formulated with other goodness and have the consistency of putty. What I've purchased is this Loctite product (http://www.homedepot.com/p/Loctite-8-fl-oz-Professional-Job-Size-Epoxy-1365736/100371835). What I'd like to know is roughly what the viscosity is, and more importantly, how epoxy does in the cleanup department? Is it a bear to remove runs/drips, will they pop off as nice and neat as white glue on wax paper, is it likely to dull any edge that gets within 3 inches, etc?

[Jim Dwight]

The fact that epoxy is gap filling also means it does not "pop off like white glue on wax paper". Runs will stick and have to be cut or sanded off. But a sharp chisel will take off a epoxy run nicely. It's actually easiest if you do not wait for it to fully cure. It is soft but not sticky when it is not quite fully cured. But if you wait until full cure, it is just hard, not at all impossible to cut with normal tools. It's a little harder than most wood but not hard to deal with. It will fill the grain in coarse wood, like oak, which may show even if you remove it from the surface.

[glenn bradley]

There are certainly people who use epoxy more than I do but, I do use it regularly for sliding dovetails in larger carcasses. It acts as a lubricant to help during the assembly of the joint. I have learned to avoid squeeze-out at all costs as the cleanup is much more work than the prep to avoid it ;-)

[Jay Jolliffe]

If you heat it with a heat gun it will scrap right off. Heat it just enough to soften it but not to much.

[Malcolm Schweizer]

I am not familiar with the LocTite epoxy, but make sure it is liquid and not gel. I use West System 105 with 207 hardener. As said, epoxy makes joints slippery. Great for dovetails, but a bit of a pain for edge glues.

Also as already said, it will fill the grain and show up after you varnish. Tape off all around the joint and remove the tape about half way through the cure while it is still "green" or still tacky.

[Tom M King]

Golfworks sells epoxy wipes that work like a miracle on wet epoxy when acetone might damage the surface. If you babysit it, and catch it before it completely kicks, a sharp chisel or disposable razor blade can shave it right off.

[Mike Hollingsworth]

masking tape helps

[Larry Edgerton]

I use it for exterior doors and my normal method is to spray the first clear coat with the areas that will be glued taped off, give them a light sanding before I put it together. Then I mask off around the area, and glue it up. When it is clamped and the tape pulled I will wipe the area off around it with alcohol. I do not use finishes that are affected by alcohol so that is something you may not be able to do.

West has fillers/micro balloons that you can use to get the consistency that you desire that will actually make the joint stronger. You do a light wet coat first then apply the epoxy with the filler and assemble. The wet coat will soak in and provide a better bond.

I use West System a lot so don't see it as all that hard to work with, and the results are better than average. I have commercial doors out there for 25 years that have not failed, and callbacks are embarrassing so that makes me happy.:D

[Mike Cutler]

I'm considering using epoxy to adhere the endcap and condor tail of my Split Top Roubo, but I have minimal experience working with the stuff. I know that some epoxies flow like water, others (which I have used a little) are formulated with other goodness and have the consistency of putty. What I've purchased is this Loctite product (http://www.homedepot.com/p/Loctite-8-fl-oz-Professional-Job-Size-Epoxy-1365736/100371835). What I'd like to know is roughly what the viscosity is, and more importantly, how epoxy does in the cleanup department? Is it a bear to remove runs/drips, will they pop off as nice and neat as white glue on wax paper, is it likely to dull any edge that gets within 3 inches, etc?

John

That particular epoxy product is not the one I would recommend. It has a very short set time, 5 minutes. I would get one with a longer open time to realize the actual benefits of epoxy in the wood shop. I would recommend an epoxy by either West, or System Three, whichever is easiest for you to obtain. Both companies have a ton of info available on how to successfully use their products.
Epoxy can take the form of stiff putty, to as runny as maple syrup and every stage in between. It's a wonderful product when chosen and applied correctly.

Epoxy can be a bear to cleanup if you don't plan for it. Mask the joints and as mentioned clean it up when it gets a gummy. Don't wait for it to harden because if it has a thixotropic agent in it, you may remove wood. It's not going to pop off like Titebond.
If you let it harden, it certainly can cause problems with plane irons and chisels. Most epoxies have a set time of a about 24 hours and a full cure of 7 days or so. If you let that epoxy set for a week or more, you'll be doing some work to remove it. Epoxy is used to coat outdoor decks, and it is essentially the same thing as you would be getting for the wood shop,with the inclusion of UV agents, flatteners, and a thixotropic agent.
It can be removed with acetone when liquid, but it tends to make a blush on the material. Blue painters tape is your better friend. Tape the joints. ;)

Okay, those are the downsides. The upside is that you have as much time as you need to do a nice neat job. You control your "pot life" to a large extent. Go slow, be methodical and neat, and you shouldn't have any worries. Don't worry about pre-staging clamps and going bonkers. You need only enough pressure to draw the joint into position. Fiberglass packing tape is a great epoxy clamp.

Tip;
Close fitting latex gloves and acid brushes, will be very handy. I promise.

[Bill Adamsen]

Lots of good advice already given. I haven't used that specific Loctite product, but the tests I've seen (https://www.jlab.org/Hall-B/notes/clas_notes94/note94-013.pdf) show the 5-minute epoxies as performing poorly in comparison to traditional marine epoxies (which have lots of users and data for a wide variety of woods). Epoxy can be gap filling and requires little to no clamping pressure. Since it is gap filling, you can actually contain it with tape dams. It cleans easily with a sharp chisel when uncured. It is TOXIC if sanded when uncured.

[Tom M King]

Get a box of nitrile gloves that you can change easily and quickly. It's really easy to get it all over everything if you get some on your fingers and hands.

[Tom M King]

Buy this stuff. One of each. It cuts faster than acetone, and doesn't smear the epoxy around. I'll also jump on the non-5minute bandwagon.

http://www.golfworks.com/product.asp_Q_pn_E_VB1015_A_cn_E_33

[ian maybury]

Another here that has thought of using a structural adhesive for a bench rather than typical woodworking glues John. Suspect though you'd be better with a purpose formulated wood bonding epoxy like the West system though. They have good tech/applications literature, in the UK anyway.

This repeats some of the guys above, but take advantage of the available long open times - but not more than you will comfortably need as it can run out of gaps in joints if given long enough before it starts to gel. As others also it's pretty much impossible to get off if it gets into a porous wood, and can show - masking tape can be helpful.

It likes lots of heat (won't cure properly if too cold, warmth improves the properties of the resulting polymer, but speeds up the cure), needs very thorough mixing at precisely the specified ratio, and doesn't bond well over itself once cured unless solvent cleaned and roughened. Even then it can be a bit iffy. The problem is that any slight surplus of one component remains caught as a liquid inside the cured material, and oozes out to make the cured surface a shade greasy. Some resins formulated for lamination of mouldings and not suitable for bonding even contain trace amounts of wax - it comes out to form a coating over the surface which prevents the air from inhibiting the cure right at the surface. (which inhibition otherwise can result in a slight long term tackiness)

It's tough but sands quite well once fully cured, but can be a bear to clog sandpaper if hit too early, or if not cured in warm enough conditions. Best got off before it cures.

Use gloves and don't handle the stuff, the amines in the typical cure system among other things is a well known allergen that more frequently than is ideal triggers reactions…

[Tom M King]

Ian, the cure issues you are talking about are some polyester resins, and don't apply to epoxy. Polyester "fiberglass" resin, like most boats are made from is much different from epoxy resins.

[Mike Schuch]

I have used that Loctite epoxy before and it does a decent job depending on what your project is.

The consistency is very much like honey. Also like honey the colder it is the thicker it is. Like everyone else stated it is easiest to shave off squeeze out before it is fully cured. The actual cure time depends on how warm the epoxy is, the warmer the faster it cures.

What are you using that epoxy for? What is your project?

[ian maybury]

I may be missing something, or over generalizing - and pardon me if i am as i'm not a chemist - but are you sure Tom? Either way i was just trying to paint a picture, and didn't set out to divert the discussion. None of the issues are blockers to using epoxies in most cases (one of my favourite adhesives), but the liking for heat, need for accurate mix ratios, need for choice of the right resin system, oxygen inhibition at the surface/wax/oozing of excess leading to the possibility of difficulty in bonding over a previous coating of epoxy are all pretty characteristic.

So far as i can recall most of the overbonding difficulty in standard resins arises from the inevitability of imperfections in the mix ratio, it's the UV/light curing variety that suffer most from oxygen inhibition. The wax issue relates primarily to laminating resins.

There are differences between formulations and resin types, but this link for example discusses the inhibition issue as it impacts UV curing resins (see from about eight posts down), an epoxy makers comes in at the end: http://forum.surfermag.com/forum/ubbthreads.php?ubb=showflat&Number=1874646&site_id=1#import Googling 'oxygen inhibition' brings up all kinds of tech papers on the topic - its an issue with many types of polymerising resin systems as well as epoxies.

Different strategies get used to tackle the re-bonding issue in different situations, and it's certainly got to be a minimal issue inside a sealed glue joint since it's unlikely to be re-coated - but it can be very significant if trying to recoat externally to smooth a fillet, or when adding a second coat to further seal a surface or something like that - especially if you end up cutting back through the top layer.

One essential difference between an epoxy and a polyester resin cure is that the epoxy is a stoichiometric system which to my only very basic understanding of the chemistry means that each molecule of cured polymer requires a given number of molecules of each of the resin components. Add a little too much of one or the other, and the surplus simply doesn't get used, and as well as producing side effects like the tacky surface mentioned the properties of the cured material rapidly disimprove. Polyester is different, in that it's a catalytic cure. The hardener by its presence triggers a cure in the already present resin. Adding extra speeds up the cure, but it makes little difference (within reasonable limits) to the final properties of the cured material.

[Mike Cutler]

Ian

You have it correct at least as far as I understand it.
A long time ago in a life far, far away, I worked in a boat yard. We repaired everything from 12 meter America's cup boats, to wooden pull boats. Now I use epoxies in high temperature electrical applications, think Nuclear Reactors. ;)

Epoxy and Fiberglass resin both have a "cure time". Most "generally" available epoxies will have three time constraints. Open time, set time and cure. General use epoxies will set in about 24 hours and will reach about 80% of their bonding strength in that period. After about a week, it will be at full bonding strength.
Epoxies have a resin and a hardener. Fiberglass has a resin and a catalyst. Epoxy cures by heat and the resin/hardner ratio needs to be correct. Polyester resins have a catalyst and cure by chemical reaction.

Tom

I really like those golf rags. I have to get me some of those. Thank you for that tip.

[Shawn Crane Davies]

We use west systems at work. Xylene and denatured alcohol work extremely well for clean up. I prefer the denatured alcohol, slightly lower flash point, stays on your clean up rag longer. A slightly damp rag with either cleans easier than the water and white/yellow glue clean up gig. Leaves no damage/staining to the wood.

[Prashun Patel]

In general, the longer the set up time, the better the holding power in epoxies. I use system three.

the viscosity of a slow setting epoxy will be like thick or cold honey.

dont try to wipe up epoxy while it sets. Use tape to mask if you must or just chisel or plane it off when dry. Chiseling epoxy a little before fully cured is easy. It's soft enough still that it peels in ribbons. Or you can wait until it's fully cured and just plane it off or sand it off. I have never had issues doing it either way.

use the recommended solvent for the epoxy to clean up spills or tools. It's usually acetone. I would not apply the solvent to the wood to clean up squeeze out when wet. You risk the solvent thinning the epoxy by penetrating into the joint too deeply. Acetone penetrates through wood way more than water so don't think just because we can use water to clean wood glue from wood that we can use acetone to clean epoxy from wood.

[Tom M King]

The only "resin" I know of that contains wax is polyester get coat. Gel coat does not completely cure in contact with air. Some of it has wax in it that floats to the surface, so it can cure, and gel coat without the wax has to be coated with something like PVA. It will almost cure without the wax, but it will never get hard enough so that it can be buffed out to a gloss. I've never had any kind of experience with any kind of laminating resin that has wax in it. One of the things I do is boat repair.

I know the conversation got way more complicated than applies to the OP's question, but all of us enjoy learning something.

After thinking more about it, for a bench build, even with as much experience as I have working with epoxy, I would not use it for a Roubo bench build. Especially if there is little to no experience working with it, I'd suggest starting on smaller projects. It has its own skill set requirements that are best learned by hands on, but not on a big project that requires that skill set to start with.

One of the good things about Epoxy, with my favorite being West, is that I haven't found the end point of shelf life yet. I keep the five gallon kit in the tool trailer for working on old houses, and it lasts for years.

[John Sanford]

I have used that Loctite epoxy before and it does a decent job depending on what your project is.

The consistency is very much like honey. Also like honey the colder it is the thicker it is. Like everyone else stated it is easiest to shave off squeeze out before it is fully cured. The actual cure time depends on how warm the epoxy is, the warmer the faster it cures.

What are you using that epoxy for? What is your project?

The project is a Split Top Roubo. I am using it only for attaching the endcap and the condor tail joint. Everything else has been/is being done with TiteBond III. I'm using the epoxy for these two joints primarily because for the gap filling characteristics. To say that tail sockets are shabby would be too high of praise.

[Tom M King]

Yeah, epoxy sounds like the right choice. Just make sure to take the masking tape off right before it sets completely up, but not too soon for it to still be runny. Just like they do with the dripping down slobbers after the top lamination of a surfboard, slice it off with a razor blade just when it's easy to work with, but won't make a bigger mess. Wait a little too long, and it's 50 times more work. Too soon, and it makes a bigger mess.

[Christopher Morgan]

Acetic acid works well for cleaning uncured epoxy off tools, etc. And it is both cheap and safe enough to put on your salad.