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. 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.

[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. 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 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...1015_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?