Slow-set epoxy?

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Forum topic by Brett posted 10-03-2012 03:18 AM 11714 views 0 times favorited 13 replies Add to Favorites Watch
View Brett's profile


660 posts in 2652 days

10-03-2012 03:18 AM

I need some slow-setting epoxy—something that has several hours of open time (I’m starting to assemble a Roubo workbench made from southern yellow pine that uses mortise-and-tenon joints; the epoxy is for these joints)

I thought I could find some at Lowes or Home Depot, but they don’t carry it. Can I slow down the cure time of regular epoxy by using more resin and less hardener? What other options do I have (besides mail-ordering some slow-setting epoxy)?

-- More tools, fewer machines.

13 replies so far

View sras's profile


4791 posts in 3098 days

#1 posted 10-03-2012 04:26 AM

If you are near a marine supply store, you may be able to find a repair kit with small amounts of epoxy in various set times.

-- Steve - Impatience is Expensive

View rockindavan's profile


299 posts in 2605 days

#2 posted 10-03-2012 04:31 AM

Whatever you do DONT CHANGE THE RATIO! If you add more resin and less hardener, there is a decent chance it will never harden. I had a buddy who mixed up epoxy in small portions at a time to fill some knots and didn’t mix properly and the epoxy didn’t harden after weeks and finally had to wash it out with solvent. West marine carries West Systems epoxy, but it is expensive, but also well worth it.

One thing to keep in mind is the open time may be say, 2 hours, but the pot time, as in the amount of time it stays good in your cup is closer to 10-15 minutes. Once the epoxy in the cup starts heating up the reaction kinda spirals out of control and cures faster than it is suppose to. One way to combat this is by spreading the epoxy out as you are using it so it wont heat up so fast.

View bondogaposis's profile


4688 posts in 2320 days

#3 posted 10-03-2012 04:44 AM

Don’t change the ratio, you may create an epoxy that never sets. Get West System epoxy and use the slow hardener for longer open time. Here is one place where you can get it. It ain’t cheap.

-- Bondo Gaposis

View Tedstor's profile


1643 posts in 2602 days

#4 posted 10-03-2012 11:50 AM

Golf stores often carry slow set epoxy. It’s used to glue the club head to the shaft.

View crank49's profile


4030 posts in 2940 days

#5 posted 10-03-2012 12:15 PM

System III slow set, at Woodcraft, is what I attached my bench legs with.
Caution, it won’t set at all if the temperature is too cool.
I was working in my basement, the temp was about 65 degrees and the stuff was not setting up till I put heat on it after waiting a couple of days.

View Wildwood's profile


2300 posts in 2104 days

#6 posted 10-03-2012 01:53 PM

I am superstitious about glue so have everything set up ready to go before applying glue. All about chemical reactions with surfaces, air, temperatures, stuff have very little control over. Not sure there is an epoxy without a 30 minute set time even if takes 24 hours to fully cure.

While most glue charts just a guide actual times can and do vary. I know from experience temperature really affects working curing times for any glue. If hot less, working, curing times cooler longer!

I try working quickly gluing, clamping, and checking for square. Normally exceed clamp time guide times. Guess only item do not use clamps on are pen blanks. If not mistaken hide glue and contact cement have longest open times.

-- Bill

View Brett's profile


660 posts in 2652 days

#7 posted 10-03-2012 02:26 PM

If I add a little water to a wood glue like Titebond III, would that give me a little more open time?

-- More tools, fewer machines.

View Lee Barker's profile

Lee Barker

2170 posts in 2819 days

#8 posted 10-03-2012 03:24 PM

Hi Brett—Franklin makes a wood glue which will give you what you want and it’s in the Titebond family.

Here is a link to the very product.

Franklin is a pretty friendly outfit to work with; if you give them a call you’ll get the straight scoop.

Similarly, calls to West System and or System Three will hook you up with a specific epoxy product for that application.

BTW, diluting regular Titebond is ok up to about 10%. It improves spreadabililty but does not increase open time.

I have not built a roubo bench but it seems to me that it can be glued up in sub assemblies in such a way that you would not have to have an octo-armed assistant to do a one-time glue-o-rama.

Contrary input is welcomed of course.



-- " his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View skruft's profile


8 posts in 2088 days

#9 posted 10-03-2012 03:50 PM

I have for many years used the West epoxy system that is designed for marine use. They have a wide choice of products but the basic system uses one resin and a choice of hardeners that give different cure times.

View Dan Lyke's profile

Dan Lyke

1519 posts in 4094 days

#10 posted 10-04-2012 12:47 AM

What everyone else has said about epoxy: Don’t change the ratio or you’ll end up with epoxy that doesn’t set, buy the good stuff, but I’d also add:

Epoxy is a two-person job: Have one person mixing extremely small batches while the other person applies it. Large batches get hot, which accelerates the set time, which makes everyone nervous, which leads to screw-ups, which…

-- Dan Lyke, Petaluma California,

View David Kirtley's profile

David Kirtley

1286 posts in 2967 days

#11 posted 10-04-2012 12:59 AM

I had both bad things happen. I mixed too big a batch and it kicked off which flustered me and I mixed the next batch with wrong proportions. It doesn’t harden and takes forever to get it all scraped off.

For that type gluing, you want additives. Neat epoxy will not do well. I really recommend System Three Gel Magic. It is a premix precisely formulated for gluing up rather than laminating. If the budget can handle it, it also has another packaging that is in tubes like caulk than mixes in the tip as you squeeze it out. It can be a lifesaver.

Plan ahead. Get everything laid out. Do a couple dry runs. Make sure everything is worked out. Go to the bathroom first (even if you don’t need to :) ), get the gloves on and go for it.

-- Woodworking shouldn't cost a fortune:

View Danpaddles's profile


573 posts in 2281 days

#12 posted 10-04-2012 01:04 AM

Lee Barker has it right- call the manufacturer. They will know more than a bunch of dusty old woodworkers. West Systems people are good to work with, and they have a wide range of mixes.

-- Dan V. in Indy

View JackieDeng's profile


7 posts in 1876 days

#13 posted 03-07-2013 10:15 AM

Beautiful epoxy paint work. That will be an heirloom.

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